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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-07-16</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000057055</issuerCik>
        <issuerName>KV PHARMACEUTICAL CO /DE/</issuerName>
        <issuerTradingSymbol>KVA / KVB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001039209</rptOwnerCik>
            <rptOwnerName>HERMELIN MARC S</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2503 S. HANLEY ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ST. LOUIS</rptOwnerCity>
            <rptOwnerState>MO</rptOwnerState>
            <rptOwnerZipCode>63144</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chairman &amp; CEO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-07-16</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F9"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>400000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>701462</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F10"/>
                    <footnoteId id="F12"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Deemed indirect beneficial owner because of status as a co-trustee and co-benef. of a family trust</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class B Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-07-16</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F22"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>400000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>622625</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F11"/>
                    <footnoteId id="F13"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Deemed indirect beneficial owner because of status as a co-trustee and co-benef. of a family trust</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-07-16</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F23"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>133333</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>979536</value>
                    <footnoteId id="F3"/>
                    <footnoteId id="F12"/>
                    <footnoteId id="F14"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Deemed indirect beneficial owner because of status as a co-trustee and co-benef. of a family trust</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class B Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-07-16</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F24"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>133333</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1747793</value>
                    <footnoteId id="F4"/>
                    <footnoteId id="F13"/>
                    <footnoteId id="F15"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Deemed indirect beneficial owner because of status as a co-trustee and co-benef. of a family trust</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-07-16</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F25"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>133333</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1101971</value>
                    <footnoteId id="F5"/>
                    <footnoteId id="F16"/>
                    <footnoteId id="F18"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Deemed indirect beneficial owner as trustee solely because beneficiary is a sibling.</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class B Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-07-16</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F26"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>133333</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2210645</value>
                    <footnoteId id="F6"/>
                    <footnoteId id="F17"/>
                    <footnoteId id="F19"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Deemed indirect beneficial owner as trustee solely because beneficiary is a sibling.</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-07-16</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F27"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>133334</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1078950</value>
                    <footnoteId id="F7"/>
                    <footnoteId id="F16"/>
                    <footnoteId id="F20"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Deemed indirect beneficial owner as trustee solely because beneficiary is a sibling.</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class B Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-07-16</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F28"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>133334</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2215709</value>
                    <footnoteId id="F8"/>
                    <footnoteId id="F17"/>
                    <footnoteId id="F21"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Deemed indirect beneficial owner as trustee solely because beneficiary is a sibling.</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Such shares of Class A Common Stock are held in one trust, of which the reporting person is a beneficiary, as well as, one of three trustees, under Trust Agreement dated 12/23/73 fbo Minnette Hermelin, mother of reporting person (the ?Minnette Hermelin Trust?).</footnote>
        <footnote id="F2">Such shares of Class B Common Stock are held in the Minnette Hermelin Trust.</footnote>
        <footnote id="F3">Such shares of Class A Common Stock are held in Trust under Trust Agreement dated 12/23/73 fbo Marc S. Hermelin, under which the reporting person is the primary beneficiary and one of three trustees (the ?Marc S. Hermelin Trust?).</footnote>
        <footnote id="F4">Such shares of Class B Common Stock are held in the Marc S. Hermelin Trust.</footnote>
        <footnote id="F5">Such shares of Class A Common Stock are held in one trust, of which the reporting person is one of three trustees, under Trust Agreement dated 12/22/1973 fbo Anne S. Kirschner, sister of reporting person (the ?Anne S. Kirschner Trust?).</footnote>
        <footnote id="F6">Such shares of Class B Common Stock are held in the Anne S. Kirschner Trust.</footnote>
        <footnote id="F7">Such shares of Class A Common Stock are held in one trust, of which the reporting person is one of three trustees, under Trust Agreement dated 12/22/1973 fbo Arnold Hermelin, brother of reporting person (the ?Arnold Hermelin Trust?).</footnote>
        <footnote id="F8">Such shares of Class B Common Stock are held in the Arnold Hermelin Trust.</footnote>
        <footnote id="F9">Acquisition by the Minnette Hermelin Trust of Class A Common Stock in exchange for a like amount of shares of Class B Common Stock from, collectively, the Marc S. Hermelin Trust, the Anne S. Kirschner Trust and the Arnold Hermelin Trust.</footnote>
        <footnote id="F10">Does not include (a) 979,536 shares of Class A Common Stock which are held in the Marc S. Hermelin Trust; and (b) 118,677 shares of Class A Common Stock owned directly by the reporting person.</footnote>
        <footnote id="F11">Does not include (a) 1,747,793 shares of Class B Common Stock which are held in the Marc S. Hermelin Trust; and (b) 1,316,613 shares of Class B Common Stock owned directly by the reporting person.</footnote>
        <footnote id="F12">Does not include (a) 2,180,921 shares of Class A Common Stock which are held in two trusts, including (i) the Arnold Hermelin Trust and (ii) the Anne S. Kirschner Trust.</footnote>
        <footnote id="F13">Does not include (a) 4,426,354 shares of Class B Common Stock which are held in two trusts, including (i) the Arnold Hermelin Trust and (ii) the Anne S. Kirschner Trust.</footnote>
        <footnote id="F14">Does not include (a) 701,462 shares of Class A Common Stock which are held in the Minnette Hermelin Trust; and (b) 118,677 shares of Class A Common Stock owned directly by the reporting person.</footnote>
        <footnote id="F15">Does not include (a) 622,625 shares of Class B Common Stock which are held in the Minnette Hermelin Trust; and (b) 1,316,613 shares of Class B Common Stock owned directly by the reporting person.</footnote>
        <footnote id="F16">Does not include: (a) 1,680,998 shares of Class A Common Stock which are held in two trusts, in each of which the reporting person is one of three trustees, including (i) the Marc S. Hermelin Trust; and (ii) the Minnette Hermelin Trust; and (b) 118,677 shares of Class A Common Stock owned directly by the reporting person.</footnote>
        <footnote id="F17">Does not include: (a) 2,370,418 shares of Class B Common Stock which are held in two trusts, in each of which the reporting person is one of three trustees, including (i) the Marc S. Hermelin Trust; and (ii) the Minnette Hermelin Trust; and (b) 1,316,613 shares of Class B Common Stock owned directly by the reporting person.</footnote>
        <footnote id="F18">Does not include 1,078,950 shares of Class A Common Stock which are held in the Arnold Hermelin Trust.</footnote>
        <footnote id="F19">Does not include 2,215,709 shares of Class B Common Stock which are held in the Arnold Hermelin Trust.</footnote>
        <footnote id="F20">Does not include 1,101,971 shares of Class A Common Stock which are held in the Anne S. Kirschner Trust.</footnote>
        <footnote id="F21">Does not include 2,210,645 shares of Class B Common Stock which are held in the Anne S. Kirschner Trust.</footnote>
        <footnote id="F22">Disposition by the Minnette Hermelin Trust of Class B Common Stock in exchange for a like amount of shares of Class A Common Stock from, collectively, the Marc S. Hermelin Trust, the Anne S. Kirschner Trust and the Arnold Hermelin Trust.</footnote>
        <footnote id="F23">Disposition by the Marc S. Hermelin Trust of Class A Common Stock in exchange for a like amount of shares of Class B Common Stock from the Minnette Hermelin Trust.</footnote>
        <footnote id="F24">Acquisition by the Marc S. Hermelin Trust of Class B Common Stock in exchange for a like amount of shares of Class A Common Stock from the Minnette Hermelin Trust.</footnote>
        <footnote id="F25">Disposition by the Anne S. Kirschner Trust of Class A Common Stock in exchange for a like amount of shares of Class B Common Stock from the Minnette Hermelin Trust.</footnote>
        <footnote id="F26">Acquisition by the Anne S. Kirschner Trust of Class B Common Stock in exchange for a like amount of shares of Class A Common Stock from the Minnette Hermelin Trust.</footnote>
        <footnote id="F27">Disposition by the Arnold Hermelin Trust of Class A Common Stock in exchange for a like amount of shares of Class B Common Stock from the Minnette Hermelin Trust.</footnote>
        <footnote id="F28">Acquisition by the Arnold Hermelin Trust of Class B Common Stock in exchange for a like amount of shares of Class A Common Stock from the Minnette Hermelin Trust.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Marc S. Hermelin, Trustee</signatureName>
        <signatureDate>2008-07-18</signatureDate>
    </ownerSignature>
</ownershipDocument>
