McKenna's Pharmacology for Nursing, 2e

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P A R T 7  Drugs acting on the reproductive system

UTERINE MOTILITY DRUGS Uterine motility drugs stimulate uterine contractions to assist labour or induce termination. Salbutamol, a beta 2 -selective adrenergic agonist, has been used as a uterine motility agent to relax the gravid uterus to prolong pregnancy. This drug is administered if uterine contractions become strong before term to prevent premature labour and delivery, which could result in detrimental effects on the neonate, including death. Sal- butamol is usually reserved for use after 20 weeks of gestation, when the fetus has a chance of survival outside of the uterus. If this drug is administered, the person will need to be monitored for sympathetic stimulation in the rest of the body (see Chapter 55, which deals with drugs used to treat obstructive pulmonary diseases, for a full discussion of salbutamol). However, nifedipine (a calcium channel blocker) is now commonly preferred in place of salbutamol. Prostaglandins are often used to “ripen” the cervix to promote the onset of labour or ter- mination of pregnancy. Oxytocics and prostaglandins are discussed in detail in this section and in Table 40.3. O xytocics Oxytocics stimulate contraction of the uterus, much like the action of the hypothalamic hormone oxytocin, which is stored in the posterior pituitary. These drugs

Evaluation

■■ In women with functioning ovaries, fertility drugs increase follicle development by stimulating FSH and LH to increase the chances for pregnancy. ■■ Women receiving fertility drugs need to be monitored for ovarian hyperstimulation, need to be aware of the possibility of multiple births and need support and encouragement to deal with the self-esteem issues associated with infertility. ■ ■ Monitor woman’s response to the drug (ovulation). ■ ■ Monitor for adverse effects (abdominal bloating, weight gain, ovarian hyperstimulation, multiple births). ■ ■ Evaluate the effectiveness of the teaching plan (woman can name drug, dosage, adverse effects to watch for and specific measures to avoid them). ■ ■ Monitor effectiveness of comfort measures and compliance with the regimen.

KEY POINTS

TABLE 40.3

DRUGS IN FOCUS Uterine motility drugs

Drug name

Dosage/route

Usual indications

Oxytocics carbetocin (Duratocin)

100 mcg by bolus IV injection over 1 minute following birth of baby; given as single dose only

Prevention and treatment of postpartum uterine atony and excessive bleeding following caesarean section under epidural or spinal anaesthesia Prevention and treatment of postpartum and postabortion uterine atony; management of third stage of labour Induction of labour; promotion of uterine contractions postpartum; management of third stage of labour

ergometrine (generic)

0.2 mg IM, may repeat doses

1–4 milliunits/min IV through an infusion pump, increase as needed, do not exceed 20 milliunits/min; 10 units IM after delivery of the placenta 20 mg vaginal pessary, may repeat q 3–5 hours as needed Vaginal gel: 1 mg intravaginally, additional 1–2 mg may be administered after 6 hours to a maximum of 3 mg Pre-op 1 mg pessary into posterior vaginal fornix. Termination one pessary q 3 hours to maximum of five pessaries

oxytocin (Syntocinon)

Prostaglandins

A prostaglandin used for evacuation of the uterus; stimulation of cervical ripening before labour

dinoprostone (Cervidil, Propedil Gel,

Prostin E2)

gemeprost (Cervagem)

Preoperative cervical softening, first or second trimester pregnancy termination

misoprostol (GyMiso)

800 mg PO 36–48 hours following oral mifepristone

Medical termination of pregnancy up to 49 days gestation