Ranitidine

Name: RANITIDINE
Class: Gastrointestinal Agent (Antisecretory)
Risk Factor: BM

Fetal Risk Summary

Ranitidine is a competitive, reversible inhibitor of histamine H2-receptors used in treatment and maintenance of patients with duodenal or gastric ulcers, pathologic hypersecretory conditions such as Zollinger-Ellison syndrome, and gastroesophageal reflux disease (GERD).

Reproduction studies with ranitidine in rats and rabbits at doses up to 160 times the human dose have revealed no evidence of impaired fertility or fetal harm (1,2 and 3). In contrast to the controversy surrounding cimetidine, ranitidine apparently has no antiandrogenic activity in humans (4) or in animals (5,6) (see also Cimetidine).

Ranitidine crosses the placenta at term to produce mean fetal:maternal ratios after 50 mg IV and 150 mg orally of 0.9 and 0.38, respectively (7,8 and 9).

In a surveillance study of Michigan Medicaid recipients involving 229,101 completed pregnancies conducted between 1985 and 1992, 516 newborns had been exposed to ranitidine during the 1st trimester (F. Rosa, personal communication, FDA, 1993). A total of 23 (4.5%) major birth defects were observed (22 expected). Specific data were available for six defect categories, including (observed/expected) 6/5 cardiovascular defects, 1/1 oral clefts, 1/0.5 spina bifida, 1/1 polydactyly, 0/1 limb-reduction defects, and 1/1 hypospadias. These data do not support an association between the drug and congenital defects.

The drug has been used alone and in combination with antacids to prevent gastric acid aspiration (Mendelson's syndrome) before vaginal delivery or cesarean section (7,8,9,10,11,12 and 13). No effect was observed in the frequency and strength of uterine contractions, in fetal heart rate pattern, or in Apgar scores (7). Neonatal gastric acidity was not affected at 24 hours. No problems in the newborn attributable to ranitidine were reported in these studies.

Ranitidine has been studied for its effectiveness in alleviating the symptoms of gastroesophageal reflux (heartburn) during pregnancy (14,15 and 16). A twice-daily dosage regimen of ranitidine was effective for this indication (14,15 and 16), including in those cases resistant to antacids alone (16). Ranitidine was also effective in controlling acid secretion in pregnant women with Zollinger-Ellison syndrome (17).

A 1996 prospective cohort study compared the pregnancy outcomes of 178 women who were exposed during pregnancy to histamine H2 blockers with 178 controls matched for maternal age, smoking, and heavy alcohol consumption (18). All of the women had contacted a Teratology Information Service concerning gestational exposure to H2-receptor antagonists (subjects) or nonteratogenic or nonfetotoxic agents (controls). Among subjects (mean daily dose in parentheses), 71% took ranitidine (258 mg), 16% cimetidine (487 mg), 8% famotidine (32 mg), and 5% nizatidine (283 mg). There were no significant differences between the outcomes of subjects and controls in terms of live births, spontaneous and elective abortions, gestational age at delivery, delivery method, birth weight, infants small for gestational age, or major malformations. Among subjects, there were 3 birth defects (2.1%) among the 142 exposed to H2 blockers in the 1st trimester: one each of atrial septal defect, ventricular septal defect, and tetralogy of Fallot. There were 5 birth defects (3.0%) among the 165 exposed anytime during pregnancy. For controls, the rates of defects were 3.5% (1st trimester) and 3.1% (anytime). There were also no differences between the groups in neonatal health problems and developmental milestones, but two children (one subject and one control) were diagnosed as developmentally delayed. The investigators concluded that 1st trimester exposure to histamine H2 blockers did not represent a major teratogenic risk (18).

Data from the Swedish Medical Birth Registry were presented in 1998 (19). A total of 553 infants (6 sets of twins) were delivered from 547 women who had used acid-suppressing drugs early in pregnancy. A number of other pharmaceutical agents, identified only by drug category, were also used by these women. Seventeen infants with birth defects were identified (3.1%; 95% confidence interval [CI] 1.8–4.9) compared with the crude malformation rate of 3.9% in the Registry. The odds ration (OR) for a congenital malformation, stratified for birth year, maternal age, parity, and smoking was 0.72 (95% CI 0.41–1.24). The OR for malformations after proton pump blocker exposure was 0.91 (95% CI 0.45–1.84) compared with 0.46 (95% CI 0.17–1.20) for H2-receptor antagonists (OR 0.86, 95% CI 0.33–2.23; p=0.13). Of the 17 infants with birth defects, 10 had been exposed to proton pump blockers, 6 to H2 antagonists, and 1 to both classes of drug. Ranitidine was the only acid-suppressing drug exposure for 156 infants. Twenty other offspring were exposed in utero to ranitidine combined either with famotidine (2 infants) or with omeprazole (18 infants). Six birth defects (3.8%) were observed in the group where ranitidine was the only acid-suppressing agent used. The defects were cerebral arteriovenous malformation, unspecified cardiac defect, hydronephrosis, undescended testicle, hypospadias, and unstable hip. Hypospadias was observed in a newborn exposed to a combination of ranitidine and omeprazole (19).

Two databases, one from England and the other from Italy, were combined for a study published in 1999 that was designed to assess the incidence of congenital malformations in women who had received a prescription during the 1st trimester for an acid-suppressing drug (ranitidine, cimetidine, and omeprazole) (20). Nonexposed women were selected from the same databases to form a control group. Spontaneous abortions and elective abortions (except two cases for anomalies that were grouped with stillbirths) were excluded from the analysis. Stillbirths were defined as any pregnancy loss occurring at 28 weeks' gestation or later. Ranitidine was taken in 322 pregnancies, resulting in 330 live births (29 [8.8%] premature), 2 stillbirths, and 1 neonatal death. Twenty (6.1%) of the newborns had a congenital malformation (shown by system): central nervous system (spina bifida/hydrocephaly), craniofacial (cleft palate only; asymmetric skull/plagiocephaly; tongue tie), eye (Duane's eye syndrome), cardiac (septal defect; anomaly of cardiac valve); musculoskeletal (dysplastic hip/dislocation/clicking hip N=3; syndactyly; sacral sinus); genital and urinary (undescended testes N=2; congenital hydrocele/inguinal hernia N=2; ovarian cyst); multiple (pyloric stenosis and talipes equinovarus); and two genetic anomalies (Hallerman-Streiff and Down's syndromes). In addition, two newborns were small for gestational age and nine had a small head circumference for gestational age. In comparison, the outcomes of 1,547 nonexposed pregnancies included 1,560 live births (115 [7.4%] premature), 15 stillbirths (includes 2 elective abortions for anomalies), and 10 neonatal deaths. Sixty-four (4.1%) of the newborns had malformations involving the following: central nervous system (N=2), head/face (N=13), eye (N=2), heart (N=7), muscle/skeletal (N=13), genital/urinary (N=18), gastrointestinal (N=2), and those of polyformation (N=3) or known genetic defects (N=4). There were 21 newborns that were small for gestational age and 78 had a small head circumference for gestational age. The relative risk of malformation (adjusted for mother's age and prematurity) associated with ranitidine was 1.5 (95% CI 0.9–2.6), with cimetidine 1.3 (95% CI 0.7–2.6), and with omeprazole 0.9 (95% CI 0.4–2.4) (20).

In summary, the absence of teratogenicity or toxicity in animals and the available human pregnancy data indicate that ranitidine is not a major teratogen. Because it has no antiandrogenic activity in animals or nonpregnant humans, ranitidine may be a safer choice than cimetidine for chronic use during pregnancy. The antiandrogenic activity of cimetidine, however, has not been observed or studied following in utero exposure (see Cimetidine).

Breast Feeding Summary

Following a single oral dose of 150 mg in six subjects, ranitidine milk concentrations increased with time, producing mean milk:plasma ratios at 2, 4, and 6 hours of 1.9, 2.8, and 6.7, respectively (21). The effect of these concentrations on the nursing infant is not known. Ranitidine decreases gastric acidity, but this effect has not been studied in nursing infants. However, cimetidine, an agent with similar activity, is considered to be compatible during breast feeding by the American Academy of Pediatrics (22).

References

1. Product information. Zantac. Glaxo Wellcome, 2000.
2. Higashida N, Kamada S, Sakanove M, Takeuchi M, Simpo K, Tanabe T. Teratogenicity studies in rats and rabbits. J Toxicol Sci 1983;8:101–50. As cited in Shepard TH. Catalog of Teratogenic Agents. 6th ed. Baltimore, MD: Johns Hopkins University Press, 1989:550.
3. Higashida N, Kamada S, Sakanove M, Takeuchi M, Simpo K, Tanabe T. Teratogenicity studies in rats and rabbits. J Toxicol Sci 1984;9:53–72. As cited in Shepard TH. Catalog of Teratogenic Agents. 6th ed. Baltimore, MD: Johns Hopkins University Press, 1989:550.
4. Wang C, Wong KL, Lam KC, Lai CL. Ranitidine does not affect gonadal function in man. Br J Clin Pharmacol 1983;16:430–2.
5. Parker S, Udani M, Gavaler JS, Van Thiel DH. Pre- and neonatal exposure to cimetidine but not ranitidine adversely affects adult sexual functioning of male rats. Neurobehav Toxicol Teratol 1984;6:313–8.
6. Parker S, Schade RR, Pohl CR, Gavaler JS, Van Thiel DH. Prenatal and neonatal exposure of male rat pups to cimetidine but not ranitidine adversely affects subsequent adult sexual functioning. Gastroenterology 1984;86:675–80.
7. McAuley DM, Moore J, Dundee JW, McCaughey W. Preliminary report on the use of ranitidine as an antacid in obstetrics. Ir J Med Sci 1982;151:91–2.
8. McAuley DM, Moore J, McCaughey W, Donnelly BD, Dundee JW. Ranitidine as an antacid before elective caesarean section. Anaesthesia 1983;38:108–14.
9. McAuley DM, Moore J, Dundee JW, McCaughey W. Oral ranitidine in labour. Anaesthesia 1984;39:433–8.
10. Gillett GB, Watson JD, Langford RM. Prophylaxis against acid aspiration syndrome in obstetric practice. Anesthesiology 1984;60:525.
11. Mathews HML, Wilson CM, Thompson EM, Moore J. Combination treatment with ranitidine and sodium bicarbonate prior to obstetric anaesthesia. Anaesthesia 1986;41:1202–6.
12. Ikenoue T, Iito J, Matsuda Y, Hokanishi H. Effects of ranitidine on maternal gastric juice and neonates when administered prior to caesarean section. Aliment Pharmacol Ther 1991;5:315–8.
13. Rout CC, Rocke DA, Gouws E. Intravenous ranitidine reduces the risk of acid aspiration of gastric contents at emergency cesarean section. Anest Analg 1993;76:156–61.
14. Larson J, Patatanian E, Miner P, Rayburn W, Robinson M. Double-blind, placebo controlled study of ranitidine (Zantac) for gastroesophageal reflux symptoms during pregnancy (abstract). Am J Obstet Gynecol 1997;176:S23.
15. Larson JD, Patatanian E, Miner PB Jr, Rayburn WF, Robinson MG. Double-blind, placebo-controlled study of ranitidine for gastroesophageal reflux symptoms during pregnancy. Obstet Gynecol 1997;90:83–7.
16. Rayburn W, Liles E, Christensen H, Robinson M. Antacids vs. antacids plus non-prescription ranitidine for heartburn during pregnancy. Int J Gynaecol Obstet 1999;66:35–7.
17. Stewart CA, Termanini B, Sutliff VE, Corleto VD, Weber HC, Gibril F, Jensen RT. Management of the Zollinger-Ellison syndrome in pregnancy. Am J Obstet Gynecol 1997;176:224–33.
18. Magee LA, Inocencion G, Kamboj L, Rosetti F, Koren G. Safety of first trimester exposure to histamine H2 blockers. A prospective cohort study. Dig Dis Sci 1996;41:1145–9.
19. Kallen B. Delivery outcome after the use of acid-suppressing drugs in early pregnancy with special Reference to omeprazole. Br J Obstet Gynaecol 1998;105:877–81.
20. Ruigomez A, Rodriguez LAG, Cattaruzzi C, Troncon MG, Agostinis L, Wallander MA, Johansson S. Use of cimetidine, omeprazole, and ranitidine in pregnant women and pregnancy outcomes. Am J Epidemiol 1999;150:476–81.
21. Riley AJ, Crowley P, Harrison C. Transfer of ranitidine to biological fluids: milk and semen. In Misiewicz JJ, Wormsley KG, eds. Proceedings of the 2nd International Symposium on Ranitidine. London. Oxford: Medicine Publishing Foundation, 1981:78–81.
22. Committee on Drugs, American Academy of Pediatrics. The transfer of drugs and other chemicals into human milk. Pediatrics 1994;93:137–50.

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