McKenna's Pharmacology for Nursing, 2e

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P A R T 7  Drugs acting on the reproductive system

in response to oxytocin activity, causing water retention by the kidney. P rostaglandins Prostglandins are used to stimulate labour or termina- tion of a pregnancy via intense uterine contractions. The available forms include gemeprost and dinopros- tone. Gemeprost ( Cervagem ) is administered via vaginal pessary usually for termination of pregnancy. Dinopros- tone ( Prostin E2, Cervidil ) assists with ripening the cervix in preparation for induction of labour and stimulates uterine contractions. It is available as a gel or pessary. Therapeutic actions and indications Prostaglandins stimulate uterine activity, dislodging any implanted trophoblasts and preventing implantation of any fertilised egg. Gemeprost is approved for use to terminate pregnancy in the second trimester of preg- nancy. See Table 40.3 for usual indications for each of these agents. Pharmacokinetics These drugs are well absorbed when administered. They are metabolised in the liver and excreted in the urine. Because of their effects on the uterus, they are used during pregnancy only to end the pregnancy. They are not recommended for use during breastfeeding. Contraindications and cautions Prostaglandins should not be used with any known allergy to prostaglandins to avoid hypersensitivity reac- tions ; after 20 weeks from the last menstrual period, which would be too late into the pregnancy for a termi­ nation ; or with active PID or acute cardiovascular, hepatic, renal or pulmonary disease, which could be exacerbated by the effects of these drugs. They are not recommended for use during breastfeeding because of the potential for serious effects on the neonate. If these drugs are to be used by a breastfeeding mother, another method of feeding the baby should be used. Caution should be used with any history of asthma, hypertension or adrenal disease, which could be exac- erbated by the drug effects , and with acute vaginitis (inflammation of the vagina) or scarred uterus, which could be aggravated by the uterine contractions . Adverse effects Adverse effects associated with prostaglandins include abdominal cramping, heavy uterine bleeding, perforated uterus and uterine rupture, all of which are related to exaggeration of the desired effects of the drug. Other adverse effects include headache, nausea and vomiting, diarrhoea, diaphoresis (sweating), backache and rash.

■ ■ Assess labour pattern, including uterine

contractions, cervical dilation and effacement, and fetal status, including fetal heart rate, rhythm and position. Institute electronic fetal monitoring as appropriate. ■ ■ Evaluate uterine tone, noting any indications of atony; assess fundal height and uterine involution, and amount and characteristics of vaginal bleeding. ■ ■ Monitor the results of laboratory tests, including coagulation studies and full blood count to ■ ■ Ensure fetal position (if appropriate) and cephalopelvic proportions to prevent serious complications of delivery. ■ ■ Regulate oxytocin delivery using an infusion pump between contractions if it is being given to stimulate labour to regulate dose appropriately. ■ ■ Monitor blood pressure and fetal heart rate frequently during and after administration to monitor for adverse effects. Discontinue the drug if blood pressure rises dramatically. ■ ■ Monitor uterine tone and involution and amount of bleeding to ensure safe and therapeutic drug use. ■ ■ Discontinue the drug at any sign of uterine hypertonicity to avoid potentially life-threatening effects ; provide life support as needed. ■ ■ Monitor fetal heart rate and rhythm if given during labour to ensure safety of the fetus. Evaluation ■ ■ Monitor woman’s response to the drug (uterine contraction, prevention of haemorrhage, milk “let down”). ■ ■ Monitor for adverse effects (blood pressure changes, uterine hypertonicity, water intoxication, ergotism). ■ ■ Evaluate the effectiveness of the teaching plan (woman can name drug, dosage, adverse effects to watch for and specific measures to avoid them). ■ ■ Monitor the effectiveness of comfort measures and compliance with the regimen. evaluate haematological status . Implementation with rationale

Safe medication administration

Name confusion has been reported among Prostin VR (alprostadil) and Prostin E2 (dinoprostone). Use extreme caution to make sure that the person is receiving the correct drug. Serious adverse effects and lack of therapeutic effects can occur if the wrong drug is given to the person.