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  <xsd:element name="FiniteLivedWebsiteDevelopmentCostsGross" id="sxtp_FiniteLivedWebsiteDevelopmentCostsGross" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="StockholdersEquityDetailsTable" id="sxtp_StockholdersEquityDetailsTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="SeriesANonVotingConvertiblePreferredStockMember" id="sxtp_SeriesANonVotingConvertiblePreferredStockMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="BridgeWarrantsMember" id="sxtp_BridgeWarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="SeriesAWarrantsMember" id="sxtp_SeriesAWarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="SeriesBWarrantsMember" id="sxtp_SeriesBWarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="PreFundedWarrantsMember" id="sxtp_PreFundedWarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="TyroneMillerMember" id="sxtp_TyroneMillerMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="GeoffreySDowMember" id="sxtp_GeoffreySDowMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="VendorsMember" id="sxtp_VendorsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="BioIntelectMember" id="sxtp_BioIntelectMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="WallachBethCapitalLLCMember" id="sxtp_WallachBethCapitalLLCMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="HCWainwrightCoLLCMember" id="sxtp_HCWainwrightCoLLCMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="January2024OfferingMember" id="sxtp_January2024OfferingMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="XuYuMember" id="sxtp_XuYuMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="StephenTooveyMember" id="sxtp_StephenTooveyMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="CharlesAllenMember" id="sxtp_CharlesAllenMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="PaulFieldMember" id="sxtp_PaulFieldMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="CherylXuMember" id="sxtp_CherylXuMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="CommonStockWarrantMember" id="sxtp_CommonStockWarrantMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="PreFundedWarrantMember" id="sxtp_PreFundedWarrantMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="JanuaryTwoThousandTwentyFourPreFundedWarrantsMember" id="sxtp_JanuaryTwoThousandTwentyFourPreFundedWarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="JanuaryTwoThousandTwentyFourWarrantMember" id="sxtp_JanuaryTwoThousandTwentyFourWarrantMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="JanuaryRepresentativeWarrantsMember" id="sxtp_JanuaryRepresentativeWarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="SeptemberTwoThousandTwentyFourPreFundedWarrantsMember" id="sxtp_SeptemberTwoThousandTwentyFourPreFundedWarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="SeriesAAndSeriesBWarrantsMember" id="sxtp_SeriesAAndSeriesBWarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="NonTradeableWarrantsMember" id="sxtp_NonTradeableWarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="UnitsIssuedDuringPeriodSharesNewIssues" id="sxtp_UnitsIssuedDuringPeriodSharesNewIssues" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="OfferingPricePerShare" id="sxtp_OfferingPricePerShare" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" />
  <xsd:element name="NumberOfShares" id="sxtp_NumberOfShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="NumberofWarrantExercisable" id="sxtp_NumberofWarrantExercisable" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="PurchaseOfGrantedShares" id="sxtp_PurchaseOfGrantedShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="PurchasedSharePrice" id="sxtp_PurchasedSharePrice" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="PreFundedWarrant" id="sxtp_PreFundedWarrant" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="SharesOfWarrants" id="sxtp_SharesOfWarrants" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="OtherOfferingExpensesPaid" id="sxtp_OtherOfferingExpensesPaid" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="AgreedToReturnShares" id="sxtp_AgreedToReturnShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="CommonStockAggregateOfferingPrice" id="sxtp_CommonStockAggregateOfferingPrice" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="ATMOfferingShares" id="sxtp_ATMOfferingShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="IPOPricePercentage" id="sxtp_IPOPricePercentage" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNumberOfWarrantsReclassifiedFromDerivativeLiabilities" id="sxtp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNumberOfWarrantsReclassifiedFromDerivativeLiabilities" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageExercisePriceReclassifiedFromDerivativeLiabilities" id="sxtp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageExercisePriceReclassifiedFromDerivativeLiabilities" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageRemainingContractualLifeYearsReclassifiedFromDerivativeLiabilities" id="sxtp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageRemainingContractualLifeYearsReclassifiedFromDerivativeLiabilities" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageRemainingContractualLifeYearsGranted" id="sxtp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageRemainingContractualLifeYearsGranted" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNumberOfWarrantsExercised" id="sxtp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNumberOfWarrantsExercised" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageExercisePriceExercised" id="sxtp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageExercisePriceExercised" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageRemainingContractualLifeYearsExercised" id="sxtp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageRemainingContractualLifeYearsExercised" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageRemainingContractualLifeYearsForfeited" id="sxtp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageRemainingContractualLifeYearsForfeited" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNumberOfWarrantsExpired" id="sxtp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNumberOfWarrantsExpired" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageExercisePriceExpired" id="sxtp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageExercisePriceExpired" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageRemainingContractualLifeYearsExpired" id="sxtp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageRemainingContractualLifeYearsExpired" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms1" id="sxtp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms1" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisable" id="sxtp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisable" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableWeightedAverageGrantDateFairValue" id="sxtp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableWeightedAverageGrantDateFairValue" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableOutstandingWeightedAverageRemainingContractualTerms" id="sxtp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableOutstandingWeightedAverageRemainingContractualTerms" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="StockholdersEquityScheduleofAssumptionsUsedInDeterminingtheFairValueofEquityClassifiedWarrantsGrantedDetailsTable" id="sxtp_StockholdersEquityScheduleofAssumptionsUsedInDeterminingtheFairValueofEquityClassifiedWarrantsGrantedDetailsTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="DebtDetailsTable" id="sxtp_DebtDetailsTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="KnightDebtMember" id="sxtp_KnightDebtMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="GeoffreySDowRevocableMember" id="sxtp_GeoffreySDowRevocableMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="KnightTherapeuticsIncMember" id="sxtp_KnightTherapeuticsIncMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="TwoThousandTwentyTwoBridgeNotesMember" id="sxtp_TwoThousandTwentyTwoBridgeNotesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="TwoThousandTwentyThreeBridgeNotesMember" id="sxtp_TwoThousandTwentyThreeBridgeNotesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="KnightsCumulativeDebtMember" id="sxtp_KnightsCumulativeDebtMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="DebentureMember" id="sxtp_DebentureMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="SmallBusinessAdministrationMember" id="sxtp_SmallBusinessAdministrationMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="BalloonPaymentMember" id="sxtp_BalloonPaymentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="VestedWarrants" id="sxtp_VestedWarrants" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="InitialPublicOfferingDiscountPercentages" id="sxtp_InitialPublicOfferingDiscountPercentages" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="CommonStockOutstandingPercentages" id="sxtp_CommonStockOutstandingPercentages" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="CumulativeDividendPercentage" id="sxtp_CumulativeDividendPercentage" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" />
  <xsd:element name="CommonStockOwnershipPercentage" id="sxtp_CommonStockOwnershipPercentage" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" />
  <xsd:element name="EqualRoyaltyPayToLenderPercentage" id="sxtp_EqualRoyaltyPayToLenderPercentage" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisMarkToMarketAdjustment" id="sxtp_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisMarkToMarketAdjustment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="AggregateAmount" id="sxtp_AggregateAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="DebtScheduleofBridgeNotesandRelatedPartyNotesDetailsTable" id="sxtp_DebtScheduleofBridgeNotesandRelatedPartyNotesDetailsTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="RelatedPartyNotesMayTwoThousandTwentyTwoMember" id="sxtp_RelatedPartyNotesMayTwoThousandTwentyTwoMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="IssuanceDateOfPromissoryNotes" id="sxtp_IssuanceDateOfPromissoryNotes" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="PromissoryNotesMaturityDate" id="sxtp_PromissoryNotesMaturityDate" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="FairValueAtModification" id="sxtp_FairValueAtModification" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAccruedInterestRecognized" id="sxtp_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAccruedInterestRecognized" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="TwoZeroTwoThreeBridgeNotesMember" id="sxtp_TwoZeroTwoThreeBridgeNotesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="TwoZeroTwoThreeBridgeNotesAndWarrantsMember" id="sxtp_TwoZeroTwoThreeBridgeNotesAndWarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="DerivativeExpenseMember" id="sxtp_DerivativeExpenseMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="ContingentMilestonePaymentMember" id="sxtp_ContingentMilestonePaymentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="BridgeSharesMember" id="sxtp_BridgeSharesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityCommitmentDate" id="sxtp_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityCommitmentDate" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="FairValueMarkToMarketAdjustmentPriorToConversionOrReclassification" id="sxtp_FairValueMarkToMarketAdjustmentPriorToConversionOrReclassification" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="DerivativeInstrumentRecognitionOfContingentMilestoneLiability" id="sxtp_DerivativeInstrumentRecognitionOfContingentMilestoneLiability" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisMarkToMarketAdjustments" id="sxtp_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisMarkToMarketAdjustments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="EffectiveIncomeTaxRateReconciliationAnnualTaxableIncome" id="sxtp_EffectiveIncomeTaxRateReconciliationAnnualTaxableIncome" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="EffectiveIncomeTaxRateReconcilationImpactOfNonUSEarningsAmount" id="sxtp_EffectiveIncomeTaxRateReconcilationImpactOfNonUSEarningsAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="EffectiveIncomeTaxRateReconcilationImpactOfNonUSEarningsPercentage" id="sxtp_EffectiveIncomeTaxRateReconcilationImpactOfNonUSEarningsPercentage" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="EffectiveIncomeTaxRateReconciliationChangeInFairValueOfPromissoryNoteRate" id="sxtp_EffectiveIncomeTaxRateReconciliationChangeInFairValueOfPromissoryNoteRate" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="ScheduleOfDeferredTaxAssetsLiabilitiesAbstract" id="sxtp_ScheduleOfDeferredTaxAssetsLiabilitiesAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="DeferredTaxAssetsLeaseLiability" id="sxtp_DeferredTaxAssetsLeaseLiability" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="FloridaStateUniversityResearchFundIncMember" id="sxtp_FloridaStateUniversityResearchFundIncMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="TwoThousandTwentyTwoEquityIncentivePlanMember" id="sxtp_TwoThousandTwentyTwoEquityIncentivePlanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="SharesOfCommonStock" id="sxtp_SharesOfCommonStock" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationScheduleofStockOptionActivitiesDetailsTable" id="sxtp_ShareBasedCompensationScheduleofStockOptionActivitiesDetailsTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantedAggregateIntrinsicValue" id="sxtp_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantedAggregateIntrinsicValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestGrantedWeightedAveragesRemainingContractualLife" id="sxtp_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestGrantedWeightedAveragesRemainingContractualLife" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeitedAggregateIntrinsicValue" id="sxtp_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeitedAggregateIntrinsicValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpiredAggregateIntrinsicValue" id="sxtp_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpiredAggregateIntrinsicValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationScheduleofRestrictedStockUnitsDetailsTable" id="sxtp_ShareBasedCompensationScheduleofRestrictedStockUnitsDetailsTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="CommitmentsandContingenciesDetailsTable" id="sxtp_CommitmentsandContingenciesDetailsTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="USGovernmentSalesMember" id="sxtp_USGovernmentSalesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="USArmyAgreementMember" id="sxtp_USArmyAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="ExpireTerm" id="sxtp_ExpireTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="NumberOfNonAuditCommitteeChairs" id="sxtp_NumberOfNonAuditCommitteeChairs" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" />
  <xsd:element name="LicensedTechnologyTerm" id="sxtp_LicensedTechnologyTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="AnnualRoyaltyPaymentPercentage" id="sxtp_AnnualRoyaltyPaymentPercentage" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="PercentageOfRoyaltyPaymentsOfNetSales" id="sxtp_PercentageOfRoyaltyPaymentsOfNetSales" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="PercentageOfTreatmentOfBabesiosis" id="sxtp_PercentageOfTreatmentOfBabesiosis" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="NumberOfDirectors" id="sxtp_NumberOfDirectors" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" />
  <xsd:element name="IssuanceOfCommonStockAndWarrantsOfUnderwritingDiscountsAndOfferingCostsPaidAtClosingAndDeferredOfferingCosts" id="sxtp_IssuanceOfCommonStockAndWarrantsOfUnderwritingDiscountsAndOfferingCostsPaidAtClosingAndDeferredOfferingCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="StockIssuedDuringPeriodSharesOfCommonStockAndWarrantsOfUnderwritingDiscountsAndOfferingCostsPaidAtClosingAndDeferredOfferingCosts" id="sxtp_StockIssuedDuringPeriodSharesOfCommonStockAndWarrantsOfUnderwritingDiscountsAndOfferingCostsPaidAtClosingAndDeferredOfferingCosts" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1Minimum" id="sxtp_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1Minimum" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1Maximum" id="sxtp_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1Maximum" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="WebsiteDevelopmentCostsAmortizationPeriod" id="sxtp_WebsiteDevelopmentCostsAmortizationPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="StockOptionsMember" id="sxtp_StockOptionsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="MilestonePayment" id="sxtp_MilestonePayment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="RoyaltyPercentage" id="sxtp_RoyaltyPercentage" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" />
  <xsd:element name="StockIssuedDuringPeriodValueIssuanceOfCommonStockAndWarrantsPursuantToJanuary2025OfferingNetOfOfferingCosts" id="sxtp_StockIssuedDuringPeriodValueIssuanceOfCommonStockAndWarrantsPursuantToJanuary2025OfferingNetOfOfferingCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="StockIssuedDuringPeriodIssuanceOfCommonStockAndWarrantsPursuantToJanuary2025OfferingNetOfOfferingCosts" id="sxtp_StockIssuedDuringPeriodIssuanceOfCommonStockAndWarrantsPursuantToJanuary2025OfferingNetOfOfferingCosts" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="StockIssuedDuringPeriodValueIssuanceOfCommonStockAndWarrantsPursuantToFebruary2025OfferingNetOfOfferingCosts" id="sxtp_StockIssuedDuringPeriodValueIssuanceOfCommonStockAndWarrantsPursuantToFebruary2025OfferingNetOfOfferingCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="StockIssuedDuringPeriodIssuanceOfCommonStockAndWarrantsPursuantToFebruary2025OfferingNetOfOfferingCosts" id="sxtp_StockIssuedDuringPeriodIssuanceOfCommonStockAndWarrantsPursuantToFebruary2025OfferingNetOfOfferingCosts" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="StockIssuedDuringPeriodValueIssuanceOfSharesForAnnualPerformanceBonusesNetOfSharesWithheldForTaxes" id="sxtp_StockIssuedDuringPeriodValueIssuanceOfSharesForAnnualPerformanceBonusesNetOfSharesWithheldForTaxes" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="StockIssuedDuringPeriodIssuanceOfSharesForAnnualPerformanceBonusesNetOfSharesWithheldForTaxesinShares" id="sxtp_StockIssuedDuringPeriodIssuanceOfSharesForAnnualPerformanceBonusesNetOfSharesWithheldForTaxesinShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="StockIssuedDuringPeriodValueIssuanceOfCommonStockAndWarrantsPursuantToJuly2025OfferingNetOfOfferingCosts" id="sxtp_StockIssuedDuringPeriodValueIssuanceOfCommonStockAndWarrantsPursuantToJuly2025OfferingNetOfOfferingCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndWarrantsPursuantToJuly2025OfferingNetOfOfferingCosts" id="sxtp_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndWarrantsPursuantToJuly2025OfferingNetOfOfferingCosts" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="NetProceedsFromJanuary2025Offering" id="sxtp_NetProceedsFromJanuary2025Offering" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="NetProceedsFromFebruary2025Offering" id="sxtp_NetProceedsFromFebruary2025Offering" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="NetProceedsFromJuly2025Offering" id="sxtp_NetProceedsFromJuly2025Offering" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="GrossSharesIssuedForAnnualPerformanceBonuses" id="sxtp_GrossSharesIssuedForAnnualPerformanceBonuses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="DirectorOneMember" id="sxtp_DirectorOneMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="NumberOfExecutive" id="sxtp_NumberOfExecutive" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" />
  <xsd:element name="SharesIssuedPayrollTaxesWithholdings" id="sxtp_SharesIssuedPayrollTaxesWithholdings" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" />
  <xsd:element name="NonqualifiedStockOptionsMember" id="sxtp_NonqualifiedStockOptionsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="LesseeOperatingLeaseExpiryDate" id="sxtp_LesseeOperatingLeaseExpiryDate" type="xbrli:dateItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="AtTheMarket2025AgreementMember" id="sxtp_AtTheMarket2025AgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="ProceedsFromCommonStockSalesAgreementNet" id="sxtp_ProceedsFromCommonStockSalesAgreementNet" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="January2025OfferingMember" id="sxtp_January2025OfferingMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="February2025OfferingMember" id="sxtp_February2025OfferingMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="July2025OfferingMember" id="sxtp_July2025OfferingMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="JanuaryTwoThousandTwentyFiveWarrantMember" id="sxtp_JanuaryTwoThousandTwentyFiveWarrantMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="FebruaryTwoThousandTwentyFiveWarrantMember" id="sxtp_FebruaryTwoThousandTwentyFiveWarrantMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="JanuaryTwoThousandTwentyFiveAgentWarrantMember" id="sxtp_JanuaryTwoThousandTwentyFiveAgentWarrantMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="FebruaryTwoThousandTwentyFiveAgentWarrantMember" id="sxtp_FebruaryTwoThousandTwentyFiveAgentWarrantMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="JulyTwoThousandTwentyFivePreFundedWarrantMember" id="sxtp_JulyTwoThousandTwentyFivePreFundedWarrantMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="JulyTwoThousandTwentyFiveAOneWarrantsMember" id="sxtp_JulyTwoThousandTwentyFiveAOneWarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="JulyTwoThousandTwentyFiveATwoWarrantsMember" id="sxtp_JulyTwoThousandTwentyFiveATwoWarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="JulyTwoThousandTwentyFiveWarrantsMember" id="sxtp_JulyTwoThousandTwentyFiveWarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="JulyTwoThousandTwentyFivePlacementAgentWarrantMember" id="sxtp_JulyTwoThousandTwentyFivePlacementAgentWarrantMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="ClassOfWarrantOrRightsExpiryTerm" id="sxtp_ClassOfWarrantOrRightsExpiryTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="ClassOfWarrantOrRightExercisableConversionDescription" id="sxtp_ClassOfWarrantOrRightExercisableConversionDescription" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="CommonStockAggregateGrossSalesProceedAuthorized" id="sxtp_CommonStockAggregateGrossSalesProceedAuthorized" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="SalesAgentCommissionPercentage" id="sxtp_SalesAgentCommissionPercentage" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" />
  <xsd:element name="CapitalizedWebsiteCostsIncludedInAccountsPayable" id="sxtp_CapitalizedWebsiteCostsIncludedInAccountsPayable" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="ReverseStockSplitFractionalSharesRoundingAdjustment" id="sxtp_ReverseStockSplitFractionalSharesRoundingAdjustment" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="ATMOfferingCostsIncludedInAccountsPayable" id="sxtp_ATMOfferingCostsIncludedInAccountsPayable" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="NasdaqStockMarketLlcMember" id="sxtp_NasdaqStockMarketLlcMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="BidPricePerShare" id="sxtp_BidPricePerShare" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="NumberOfConsecutiveBusinessDays" id="sxtp_NumberOfConsecutiveBusinessDays" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="HearingFeeAmount" id="sxtp_HearingFeeAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="TrevallyLlcMember" id="sxtp_TrevallyLlcMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="SharesReturnConsideration" id="sxtp_SharesReturnConsideration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="UnamortizedBalance" id="sxtp_UnamortizedBalance" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="RelatedPartiesPolicyTextBlock" id="sxtp_RelatedPartiesPolicyTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="NatureofOperationsDetailsLineItems" id="sxtp_NatureofOperationsDetailsLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="SummaryofSignificantAccountingPoliciesDetailsLineItems" id="sxtp_SummaryofSignificantAccountingPoliciesDetailsLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="StockholdersEquityDetailsLineItems" id="sxtp_StockholdersEquityDetailsLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="CommitmentsandContingenciesDetailsLineItems" id="sxtp_CommitmentsandContingenciesDetailsLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="March2026AtTheMarketAgreementMember" id="sxtp_March2026AtTheMarketAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="CommonStockAggregateGrossSalesProceedAuthorizedIncrease" id="sxtp_CommonStockAggregateGrossSalesProceedAuthorizedIncrease" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="WebsiteDevelopmentCostsPolicy1TextBlock" id="sxtp_WebsiteDevelopmentCostsPolicy1TextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="ValuationOfContingentMilestonePaymentDiscountRate" id="sxtp_ValuationOfContingentMilestonePaymentDiscountRate" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xsd:element name="UnamortizedBalancePrepaidAssets" id="sxtp_UnamortizedBalancePrepaidAssets" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="UnamortizedBalanceOfPrepaidAssetsRecognizedRatablyOverRemainingServicePeriod" id="sxtp_UnamortizedBalanceOfPrepaidAssetsRecognizedRatablyOverRemainingServicePeriod" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="UnamortizedBalanceOfPrepaidAssetsRemainingBalanceRecognizedAsResearchAndDevelopmentServices" id="sxtp_UnamortizedBalanceOfPrepaidAssetsRemainingBalanceRecognizedAsResearchAndDevelopmentServices" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:balance="debit" xbrli:periodType="instant" />
</xsd:schema>
