McKenna's Pharmacology for Nursing, 2e

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

TABLE 40.1

DRUGS IN FOCUS Sex hormones and oestrogen receptor modulators (continued)

Drug name

Dosage/route

Usual indications

nomegestrol (Zoely)

1 tablet (2.5 mg nomegestrel, 1.5 mg oestradiol) PO daily

Oral contraception

2.5–10 mg/day PO

Used in combination contraceptives; used alone for treatment of amenorrhoea Used as contraceptive and in fertility programs; treatment of amenorrhoea Used therapeutically to stimulate specific oestrogen receptor sites, which results in an increase in bone mineral density without stimulating the endometrium in women; reduces risk of invasive breast cancer in postmenopausal women with osteoporosis who are at high risk for invasive breast cancer Used as an antineoplastic agent because of its effects on oestrogen receptor sites (see Chapter 14) for treatment of advanced breast cancer in postmenopausal women with oestrogen receptor–positive and oestrogen receptor–unknown tumours

norethisterone (Primolut)

progesterone (generic)

25–200 mg/day intravaginally

Oestrogen receptor modulators raloxifene (Evista)

60 mg/day PO

toremifene (Fareston)

60 mg/day PO

Oestrogens Therapeutic actions and indications

oral contraceptives (OC), to promote calcium retention in osteoporosis and for palliation in certain cancers that have known receptor sensitivity (see Chapter 14). See Table 40.1 for usual indications for each type of oestro- gen. See also Box 40.4 for a discussion of the advantages and disadvantages of HRT. Oestrogens are important for the development of the female reproductive system and secondary sex characteristics. They affect the release of pituitary follicle- stimulating hormone (FSH) and luteinising hormone (LH); cause capillary dilation, fluid retention, protein anabolism and thin the cervical mucus; conserve calcium and phosphorus, and encourage bone formation; inhibit ovulation; and prevent postpartum breast discomfort. Oestrogens are also responsible for the proliferation of the endometrial lining (Figure 40.1). An absence or decrease in oestrogen produces the signs and symptoms of menopause in the uterus, vagina, breasts and cervix. Oestrogens are known to compete with androgens for receptor sites; this trait makes them beneficial in certain androgen-dependent prostate cancers. Oestrogens produce a wide variety of systemic effects, including pro- tecting the heart from atherosclerosis, retaining calcium in the bones and maintaining the secondary female sex characteristics (see Box 39.1 in Chapter 39 for a complete list of oestrogen effects). Pharmacokinetics Oral oestrogens are well absorbed through the gastro­ intestinal (GI) tract and undergo extensive hepatic

Oestrogens are used in many clinical situations; for example, in small doses, they are used for hormone replacement therapy (HRT) when ovarian activity is blocked or absent. (Box 40.2 lists combination products used as HRT.) Oestrogens are also used as palliation for discomforts of menopause when many of the beneficial effects of oestrogen are lost, or as part of combination

■■ BOX 40.2  Combination drugs used for menopause

Many fixed-combination drugs containing oestrogen and a progestin are available specifically for relieving the signs and symptoms associated with menopause in women who have an intact uterus. The benefits include reduction in the risk of osteoporosis and coronary artery disease with short-term use. These drugs are taken as one tablet, once a day. Women should receive regular medical follow-up and monitoring while taking these drugs. ethinyloestradiol/drospirenone ( Yasmin, Yaz ) oestradiol/drospirenone ( Angeliq ) oestradiol/norethisterone ( Kliogest, Kliovance ) oestradiol/dydrogesterone ( Femoston ) medroxyprogesterone/oestrogen, conjugated ( Premia ) norethisterone/oestradiol ( Trisequens ) Also available as a combination patch: oestradiol/ norethisterone ( Estalis, Estracombi, Kliogest, Kliovance )