Progestins are hormones naturally secreted by the ovary mainly from the corpus luteum during the second half of the menstrual cycle, from the placenta during pregnancy, and from adrenal glands in both sexes. Progestins are also available as synthetic steroidal compounds. Natural progesterone is a crystalline substance similar to androsterone. It induces extensive proges-tational development necessary for implantation of the ovum. Agents similar to progesterone include hydroxyprogesterone caproate, medrogestone, and medroxyprogesterone acetate. Agents similar to 19-nortestosterone include norethandrolone, norethindrone, norethynodrel, norgestrel, desogestrel, and norg-estimate. Other examples of progestins include allyloestrenol, dydrogesterone and norethisterone.
Progestins are used for a number of purposes, including treatment of amenorrhoea, abnormal uterine bleeding, hypoven-tilation, contraception (routine, as well as emergency contra-ception) and management of bleeding during post-menopausal therapy. Progestins are used (with oestrogens) for hormone replacement therapy in post-menopausal women, and (with or without oestrogens) for contraception.
Chronic toxicity can result in headache, irregular menses, mastalgia, bloating, decreased libido, GI upsets, weight gain, oedema, acne, rash, urticaria, breast discomfort, mental depres-sion, hypertension, insomnia, vertigo, alopecia, thromboem-bolic phenomena, hepatotoxicity.
Acute attacks of porphyria can be precipitated by proges-terone. Common signs and symptoms of an acute attack may include abdominal pain, nausea, vomiting, constipation, tachy-cardia, hypertension, depression, anxiety, irritability, fatigue or other mood changes, restlessness, fine tremors, excessive sweating, pain in the limbs, head, neck, or chest, muscle weakness, or sensory loss. Diagnosis is based on the increased urinary excretion of porphyrin precursors delta-aminolevulinic acid and porphobilinogen.
Ingestion of progestins during early pregnancy may cause virilisation of the female foetus, chromosomal abnormalities, or congenital malformations. Congenital malformations such as Tetralogy of Fallot or chromosomal anomalies such as geni-tourinary abnormalities, may also occur.
Single acute overdoses will seldom result in toxicity. Gastric decontamination should be considered after large or mixed ingestions. Supportive treatment will be adequate in most situations.