C H A P T E R 4 0
Drugs affecting the female reproductive system
609
Oestrogens
Therapeutic actions and indications
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
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
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
norethisterone
(Primolut)
2.5–10 mg/day PO
Used in combination contraceptives; used
alone for treatment of amenorrhoea
progesterone (generic)
25–200 mg/day intravaginally
Used as contraceptive and in fertility
programs; treatment of amenorrhoea
Oestrogen receptor modulators
raloxifene (Evista)
60 mg/day PO
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
toremifene (Fareston)
60 mg/day PO
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
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
)
■■
BOX 40.2
Combination drugs used for
menopause
