Drug delivery system comprising a tetrahydroxilated estrogen for use in hormonal contraception

A pharmaceutical kit comprising at least 20 oral dosage units, wherein at least 10 units contain between 0.01 and 20 mg of an estrogenic component and at least 10 units contain a progestogenic component in an amount equivalent to 30-750 μg levonorgestrel, said estrogenic component being selected from the group consisting of substances represented by the following formula:

• in which formula R1, R2, R3, R4 independently are a hydrogen atom, a hydroxyl group or an alkoxy group with 1-5 carbon atoms;
• each of R5, R6, R7 is a hydroxyl group;
• and no more than 3 of R1, R2, R3, R4 are hydrogen atoms;
• precursors capable of liberating a substance according to the aforementioned formula when used in the present method, which precursors are derivatives of the aforementioned estrogenic substances wherein the hydrogen atom of at least one of the hydroxyl groups has been substituted by an acyl radical of a hydrocarbon carboxylic, sulfonic or sulfamic acid of 1-25 carbon atoms;
• tetrahydrofuranyl;
• tetrahydropyranal;
• or a straight or branched chain glycosidic residue containing 1-20 glycosidic units per residue;
• and
• mixtures of one or more of the aforementioned substances or precursors, wherein the oral dosage units do not contain an LHRH composition.