<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-09-30</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0000929547</issuerCik>
        <issuerName>INKINE PHARMACEUTICAL CO INC</issuerName>
        <issuerTradingSymbol>INKP</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001316741</rptOwnerCik>
            <rptOwnerName>Cullen John</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1787 SENTRY PARKWAY WEST</rptOwnerStreet1>
            <rptOwnerStreet2>BUILDING 18 SUITE 440</rptOwnerStreet2>
            <rptOwnerCity>BLUE BELL</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>19422</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isOfficer>1</isOfficer>
            <officerTitle>Sr. VP and GC</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Copmmon Stock (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>3.05</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-09-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>50000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2015-03-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>50000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">All of the options described above were converted in the merger into options to purchase Salix common stock based on an exchange ratio of 0.1737. These options, which are fully vested, now represent the right to purchase 8,685 shares of Salix common stock at a weighted average exercise price of $17.56 per share.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Robert F. Apple, as attorney-in-fact for John M. Cullen, Ph.D., J.D.</signatureName>
        <signatureDate>2005-10-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
