Drugs Acting on the Uterus

Ergonovine and methylergonovine botli increase the strengtli, duration, and frequency of uterine contractions and decrease tlie incidence of uterine bleeding. They are given after tlie delivery of the placenta and are used to prevent poshiartum and postabortal hemorrh e caused by uterine atony (marked relaxation of the uterine muscle). 

Oxytocic dru are dni tliat are used in antepartum (before birtli of tlie neonate) to induce uterine contractions similar to those of normal labor. These dni are desirable when early vaginal delivery is in tlie best interest of the woman and tlie fetus. 

SUMMARY DRUG TABLE DRUGS ACTING ON THE UTERUS 

Routine management after delivery of the placenta, uterine atony, and hemorrhage Antepartum to initiate or improve uterine contractions postpartum to produce uterine contractions in third stage of labor, control of postpartum bleeding and hemorrhage 

Nausea, vomiting, elevated blood pressure, temporary chest pain, dizziness, headache Nausea, vomiting, elevated blood pressure, transient chest pain, dizziness, headache 

GENERIC NAME TRADENAME USES ADVERSE REACTIONS DOSAGERANGES 

Administration of oxytocin may result in fetal bradycardia, uterine rupture, uterine hypertonicity, nausea, vomiting, cardiac arrhythmias, and anaphylactic reactions. Serious water intoxication (fluid overload, fluid volume excess) may occur, particularly when the drug is administered by continuous infusion and the patient is receiving fluids by mouth. When used as a nasal spray, adverse reactions are rare. 

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Unit IX discusses drugp that affect the endocrine system and consists of five chapters antidiabetic drugs, pituitary and andrenocortical hormones, thyroid and antitliyroid drag s, male and female hormones, and dragp acting on the uterus. 

BERDE B., SAAMELI K. Evaluation of substances acting on the uterus. In Methods in Drug Evaluation (P.MANTEGAZZA, P.PICCININI, ed.). North-Holland Publ.Co., Amsterdam 1966, p.481. 

Selective Estrogen Receptor Modulators Raloxifene (EVISTa) acts as an estrogen agonist on bone and liver, is inactive on the uterus, and acts as an estrogen antagonist on the breast. In postmenopausal women, raloxifene modestly increases bone mineral density and has been shown to reduce the risk of vertebral compression fractures in this setting, it is approved for both the prevention and treatment of osteoporosis. The major adverse effect is worsened vasomotor symptoms the drug also increases the incidence of deep venous thrombosis. 

Several drugs act on smooth muscle, seemingly quite independently of the nervous impulse. Histamine (7.6), a tissue hormone, causes contraction of the intestine and uterus, and dilatation of the muscular fibres of blood-vessels. A number of excellent antihistaminic drugs have been synthesized and are dealt with in Section 9.4. 5-Hydroxytryptamine (7.56), another widespread hormone, whose peripheral functions are obscure, causes strong contractions in smooth muscle. 

In humans infected with O. volvulus, ivermectin causes a rapid, marked decrease in microfi-larial counts in the skin and ocular tissues that lasts for 6—12 months. The drug has little discernible effect on adult parasites, even at doses as high as 800 ig/kg, but affects developing larvae and blocks egress of microfilariae from the uterus of adult female worms. Regular treatment with ivermectin also may act prophylactically against the development of Onchocerca infection. 

If contractions are frequent, prolonged, or excessive, die infusion is stopped to prevent fetal anoxia or trauma to die uterus. Excessive stimulation of die uterus can cause uterine hypertonicity and possible uterine rupture. The nurse places die patient on her side and provides supplemental oxygen. The effects of die drug diminish rapidly because oxytocin is short acting. 

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