Heragest Drug Interactions

Drugs Inducing Liver Enzymes (e.g., carbamazepine, griseofulvin, barbiturates, hydantoins, meprobamates, phenylbutazone, or rifampicin): The metabolism of progesterone may be enhanced and its activity reduced by compounds that induce liver enzymes.
Cytochrome P450 Inhibitors: Ketoconazole (an inhibitor of CYP450 3A4) inhibited the metabolism of progesterone. An increase in the bioavailability of progesterone may be expected; however, the relevance of this in vitro finding is unknown.
The bioavailability of medroxyprogesterone acetate may be significantly reduced when concomitantly administered with aminoglutethimide. It is unknown whether this interaction occurs with progesterone.
Antidiabetic Agents: Progesterone can decrease glucose tolerance and therefore an adjustment in the antidiabetic dosage may be required.
Bromocriptine: Bromocriptine inhibits prolactin. This may interfere with the effects of progesterone resulting in a decreased progesterone action.
Ciclosporin: Progesterone may inhibit ciclosporin metabolism leading to increased plasma ciclosporin concentrations.
Conjugated Estrogens: Co-administration of conjugated estrogens and progesterone resulted in an increase in total estrone concentrations and total equilin concentrations and a decrease in circulating 17β estradiol concentration. The half-life of the conjugated estrogens was similar with co-administration of progesterone.
Herbal Products: Some herbal products such as St John's Wort may reduce the effect of progesterone.
Food: Food increases the bioavailability of progesterone relative to a fasting state when administered at a dose of 200 mg. Progesterone significantly increases AUC and C_max values with no effect on T_max.
The following laboratory results may be altered by the use of estrogen and progestin therapy: Increased sulfobromophthalein retention and other hepatic function tests, coagulation tests (increase in prothrombin factors VII, VIII, IX, and X), pregnanediol determination, thyroid function (increases in PBI, and butanol extractable protein bound iodine and decrease in T3 uptake values).