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C H A P T E R 4 0 Drugs affecting the female reproductive system

The evidence (continued)

BOX 40.4

The current recommendation of the US Preventative ServicesTask Force is that women should feel comfortable taking HRT to reduce the symptoms of menopause for short-term therapy (fewer than 5 years).The task force summarised all of the studies and noted that long-term use of HRT provides a decreased risk of osteoporosis and related fractures, possibly a reduced risk of dementia and a reduction in risk of colon cancer.The negative aspects of this therapy include a definite but small increased risk for heart disease, stroke and breast cancer.The harms of long-term use outweigh the benefits for most women.The

Contraindications and cautions Contraindications and cautions for progestogens are similar to those for oestrogens. Progestogens are also contraindicated in the presence of pelvic inflammatory disease (PID), sexually transmitted infections, endo- metriosis or pelvic surgery because of the effects of progestogens on the vasculature of the uterus. Dros- pirenone is contraindicated in people who are at risk of hyperkalaemia due to renal disorders, liver disease, adrenal dysfunction or the use of other drugs that can affect potassium levels because of its antimineralocorti- coid effects and the risk of hyperkalaemia. Progestogens should be used with caution in people with epilepsy, migraine headaches, asthma or cardiac or renal dysfunction because of the potential exacerbation of these conditions. Adverse effects Adverse effects associated with progestogens vary with the administration route used. Systemic effects are very similar to the adverse effects of oestrogen. Dermal patch contraceptives are associated with the same systemic effects, as well as local skin irritation. Vaginal gel use is associated with headache, nervousness, constipa- tion, breast enlargement and perineal pain. Intrauterine systems are associated with abdominal pain, endome- triosis, abortion, PID and expulsion of the intrauterine device. Vaginal use is associated with local irritation and swelling. Drospirenone, used in combination con- traceptives, has anti-mineralocorticoid activity and can block aldosterone, leading to increased potassium levels. Clinically important drug–drug interactions Interaction with barbiturates, carbamazepine, pheny- toin, griseofulvin, penicillins, tetracyclines or rifampicin may reduce the effectiveness of progestogens. People using any of these drugs should use another method of contraception if birth control is needed. St John’s wort can affect the metabolism of progestogens and can make progestogen-containing contraceptives less effective. This combination should be discouraged. benefits of short-term use, however, must be considered if a woman is having a difficult time getting through menopause (US Preventative ServicesTask Force, 2002). Critics of the study also point out that the women in the study were much older than most early postmenopausal groups who could benefit from HRT; they concluded that more research is needed on this issue (Neves-e-Castro, 2003). Follow-up research using this study has found no correlation between use of HRT and the prevention of Alzheimer’s disease: no drop in bone fractures in women using HRT.

Herbal and alternative therapies

BOX 40.5

black cohosh: 40 mg/day active ingredient, should not be used for longer than 60 days; monitor for dizziness, nausea, vomiting, visual disturbances; contains alcohol—do not combine with disulfiram, metronidazole. borage: 90–500 mg/day PO in soft gel capsules, not for long-term use; use caution with seizure disorders or liver impairment. chaste tree: 150–325 mg PO once or twice daily; may cause increased blood pressure—avoid use with antihypertensives or beta-blockers; may cause rash and itching. clary: 8 drops (gtt) in 30 mL of water daily as an atomiser or dissolved in bath water; may cause sedation—avoid use with alcohol; not for internal use. devil’s claw: 1.5–6 g/day PO depending on preparation; increases stomach acid and may interfere with many prescription drugs; use with caution. dong quai: 500 mg/day PO; causes photosensitivity— avoid exposure to the sun; do not use with warfarin— increased bleeding can occur. false unicorn root: 1–2 mL PO three times a day; do not use with oestrogen or progestins—may alter uterine effects. red clover: 4 g PO three times a day as tea; 30–60 gtt PO three times a day of liquid extract; do not use with heparin or warfarin because of increased bleeding effects; do not combine with hormone replacement therapy because of risk of increased oestrogenic effects. soy: 25 g/day PO; do not use with calcium, iron or zinc products; may decrease effects of oestrogen, raloxifene, tamoxifen—alert healthcare provider if combining these drugs. wild yam: 1–6 g/day PO; contains progesterone—do not use with hormone replacement therapy; may cause increased blood glucose and other toxic effects; do not combine with disulfiram or metronidazole—severe reaction may occur.