PAL-
I wanted to respond to your post earlier but got bogged down in RESEARCH on this- Almost a half day's worth...Couldn't
stop! (
Gimme a pill for CRS (Compulsive Research Syndrome).
Like you, I found an unbelievable amount of conflicting information regarding the risk category for thiazide use in pregnancy. As you said, B to D.
I found that the pregnancy risk factor for CERTAIN thiazides is
Category B...(chlorothiazide, chlorthalidone,
hydrochlorothiazide, indapamide, metolazone) BUT bendroflumethiazide, benzthiazide, hydroflumethiazide, methyclothiazide, trichlormethiazide are designated category
C.
" CATEGORY C - Safety for use during pregnancy has not been established....
Restrict use to women with volume-overload states (eg, renal or cardiac disease)"
But the way category B as described in the literature for thiazides is extremely confusing. On the one hand the studies state that "hydrochlorothiazide administered to mice and rats provided no evidence of fetal harm" but THEN they go on to tell us that since there have been no adequate or well-controlled studies in pregnant
women, and since thiazides cross the placental barrier, theoretically they can compromise placental blood flow with a risk of causing either fetal OR neonatal jaundice and thrombocytopenia and hemolytic anemia. Newborns may also develop hypoglycemia at birth.
Sounds to me like it's a Category B only if you're a rodent!
Further digging found, as you did, several references to thiazides being Category D in pregnancy:
"Category D — Positive evidence of human fetal risk exists, but benefits in certain situations (for example, life-threatening situations or serious diseases for which safer drugs cannot be used or are ineffective) may make use of the drug acceptable despite its risks. (This means there is strong evidence of a risk of loss of pregnancy or birth defects that must be balanced against the value of treatment.)
And not to be forgotten, is the fact that thiazides may cause hypotension or electrolyte imbalance in the
mom, therefore possibly (likely) affecting the fetus or newborn.
Aldomet seems to be the universal drug of choice in pregnancy.
A few British sources say:
2nd choice- Calcium Channel Blockers- specifically Nifedipine."Use during pregnancy must be evaluated on a case-by-case basis."
3rd choice-Betablockers - Propranolol, Atenolol. "Limited experience in first trimester. In late pregnancy can cause neonatal hypoglycemia and bradycardia. Avoid in first trimester if possible."
ACE Inhibitors - Captopril, Enalapril etc.- "Serious problems in the foetus may occur such as oligohydramnious and renal dysfuction after exposure in second and third trimenster. Contraindicated
Angiotensin receptor antagonists - Losartan et al- As for ACE inhibitors Contraindicated
Well. There you have it. Overall, It would seem wise to steer clear of thiazides if humanly possible.
Hopefully Mary will do very well on the Aldomet monotherapy.
zuzu xx
Some of my sources: American College of Physicians-American Society of Internal Medicine, Royal College of Physicians and Surgeons of Canada, Society of General Internal Medicine, and Society of Obstetric Medicine.
