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Hydrochlorothiazide / triamterene Pregnancy and Breastfeeding Warnings

Hydrochlorothiazide / triamterene is also known as: Dyazide, Maxzide, Maxzide-25

Hydrochlorothiazide / triamterene Pregnancy Warnings

The Collaborative Perinatal Project monitored 50,282 mother-child pairs, of whom 233 were exposed to thiazide or related diuretics during the first trimester. An increased risk of malformations was found for thiazide diuretics. Use of thiazides after the first trimester does not seem to carry this risk. Thiazide diuretics may, however pose metabolic risks to the mother and fetus (hyponatremia, hypokalemia, thrombocytopenia, hyperglycemia), and may have a direct effect on smooth muscle, resulting in inhibition of labor. Cases of neonatal thrombocytopenia associated with antepartum administration of thiazide diuretics have been reported. Data from the Michigan Medicaid Birth Defects study failed to reveal an association between triamterene or thiazide diuretics and congenital defects (written communication, Franz Rosa, MD, Food and Drug Administration, 1994). Of 229,101 completed pregnancies between 1985 and 1992, 318 were exposed to triamterene at some time during the first trimester and 640 were exposed to the drug at any time during pregnancy. Of these pregnancies, 15 total and 3 cardiovascular defects were observed (13 and 3 were expected, respectively). A single case of cleft palate was observed. None of the observations achieved statistical significance. Regarding hydrochlorothiazide (HCTZ), this report is a summary of two studies, one in which 390 of 104,000 pregnant women from 1980 to 1983, and one in which 567 of 229,101 pregnant women from 1985 to 1992 received HCTZ. In the first study 28 total and 6 cardiovascular birth defects were observed (25 and 4 were expected, respectively). In the second study, 24 total defects and 7 cardiovascular defects were observed (22 and 6 were expected, respectively). Cleft palate was not associated with HCTZ. These data do not support an association between triamterene or HCTZ and congenital defects.

Hydrochlorothiazide-triamterene has been assigned to pregnancy category C by the FDA. No animal or human pregnancy data on the combination drug are available. In general, diuretics are often considered contraindicated in pregnancy, except for patients with heart disease, since they may decrease placental perfusion. Animal studies in rats have failed to reveal evidence of teratogenicity when given triamterene in doses up to 30 times the human dose (on a per kg basis). No controlled studies in human pregnancy are available. Data have revealed active human placental passage of triamterene from mother to fetus. A retrospective study of 271 human exposures to triamterene during pregnancy revealed no increase in malformations. Hydrochlorothiazide-triamterene should only be given during pregnancy when there are no alternatives and benefit outweighs risk.

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Hydrochlorothiazide / triamterene Breastfeeding Warnings

Hydrochlorothiazide-triamterene is excreted into human milk. Side effects in the nursing infant are unlikely, but experience with the combination drug or with triamterene alone is limited. Hydrochlorothiazide is considered compatible with breast-feeding by the American Academy of Pediatrics; however, the manufacturer recommends that due to the potential for serious adverse reactions in nursing infants, a decision should be made to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.

In one case, in which a mother was taking hydrochlorothiazide 50 mg daily, 25% of her plasma HCTZ concentration appeared in her milk. This usually represents an insignificant amount of hydrochlorothiazide to the infant such that adverse effects in the nursing infant are unlikely. No data are available on the excretion of triamterene alone into human milk.

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References for pregnancy information

  1. Lindheimer MD, Katz AI "Sodiuim and diuretics in pregnancy." N Engl J Med 288 (1973): 891-4
  2. "Product Information. HydroDIURIL (hydrochlorothiazide)." Merck & Co, Inc, West Point, PA.
  3. Rodriguez SU, Sanford LL, Hiller MC "Neonatal thrombocytopenia associated with ante-partum administration of thiazide drugs." N Engl J Med 270 (1964): 881-4
  4. Heinonen O, Slone D, Shapiro S; Kaufman DW ed. "Birth Defects and Drugs in Pregnancy." Littleton, MA: Publishing Sciences Group, Inc. (1977): 297

References for breastfeeding information

  1. Committee on Drugs, 1992 to 1993 "The transfer of drugs and other chemicals into human milk." Pediatrics 93 (1994): 137-50
  2. Werthmann MW, Krees SV "Excretion of chlorothiazide in human breast milk." J Pediatr 81 (1972): 781-3
  3. Miller ME, Cohn RD, Burghart PH "Hydrochlorothiazide disposition in a mother and her breast-fed infant." J Pediatr 101 (1982): 789-91
  4. "Product Information. HydroDIURIL (hydrochlorothiazide)." Merck & Co, Inc, West Point, PA.

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