UNIRETIC
Clinical safety rating: caution
Comprehensive clinical and safety monograph for UNIRETIC (UNIRETIC).
Uniretic is a combination of an angiotensin-converting enzyme (ACE) inhibitor (moexipril) and a thiazide diuretic (hydrochlorothiazide). Moexipril inhibits ACE, preventing conversion of angiotensin I to angiotensin II, reducing vasoconstriction and aldosterone secretion. Hydrochlorothiazide inhibits sodium reabsorption in distal convoluted tubule, increasing excretion of sodium and water.
| Metabolism | Moexipril: Hepatic (ester hydrolysis to active moexiprilat), further glucuronidation; Hydrochlorothiazide: Not metabolized. |
| Excretion | Renal: 50-70% unchanged; biliary/fecal: 10-15% as metabolites |
| Half-life | Terminal elimination half-life 13-17 hours; clinical context: supports once-daily dosing |
| Protein binding | 95% to albumin |
| Volume of Distribution | 4.5 L/kg; indicates extensive extravascular distribution |
| Bioavailability | Oral: 73% |
| Onset of Action | Oral: 1-2 hours for maximal antihypertensive effect; steady-state in 1-2 weeks |
| Duration of Action | 24 hours; clinical note: consistent blood pressure control over 24 hours with single daily dose |
1-2 tablets (each containing hydrochlorothiazide 25 mg and spironolactone 25 mg) orally once daily. Maximum dose: 4 tablets/day.
| Dosage form | TABLET |
| Renal impairment | GFR 30-60 mL/min: initiate at lowest dose (1 tablet daily) and monitor electrolytes. GFR <30 mL/min: contraindicated due to risk of hyperkalemia and azotemia. |
| Liver impairment | Child-Pugh A: no adjustment needed. Child-Pugh B: use with caution, consider dose reduction to 1 tablet daily. Child-Pugh C: contraindicated. |
| Pediatric use | Safety and efficacy not established; use not recommended in pediatric patients. |
| Geriatric use | Initiate at lowest dose (1 tablet daily); monitor renal function, electrolytes, and orthostatic blood pressure closely. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for UNIRETIC (UNIRETIC).
| Breastfeeding | Hydrochlorothiazide is excreted in human milk in small amounts; spironolactone's active metabolite, canrenone, is present in milk. M/P ratio not established. Due to potential for adverse effects in nursing infants (e.g., electrolyte imbalances, antiandrogenic effects), breastfeeding is not recommended during UNIRETIC therapy. Discontinue drug or nursing. |
| Teratogenic Risk | UNIRETIC (hydrochlorothiazide and spironolactone) is contraindicated in pregnancy. First trimester: Limited human data; animal studies suggest potential risk based on spironolactone's antiandrogenic effects. Second and third trimesters: Hydrochlorothiazide may cause fetal/neonatal jaundice, thrombocytopenia, and electrolyte disturbances. Spironolactone's antiandrogenic effects may impact male fetal genital development. Use only if potential benefit justifies risk to fetus. |
■ FDA Black Box Warning
Fetal toxicity: Drugs acting directly on renin-angiotensin system can cause injury and death to developing fetus. Discontinue as soon as pregnancy is detected.
| Serious Effects |
["Pregnancy","History of angioedema related to previous ACE inhibitor therapy","Anuria (due to HCTZ)","Hypersensitivity to moexipril, hydrochlorothiazide, or sulfonamide-derived drugs"]
| Precautions | ["Fetal toxicity","Hypotension in volume-depleted patients","Renal impairment","Electrolyte imbalances (hyperkalemia, hyponatremia, hypomagnesemia)","Acute angle-closure glaucoma (with HCTZ)","Sulfonamide allergy (cross-reactivity with HCTZ)","Cough, angioedema (ACE inhibitor)"] |
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| Fetal Monitoring | Monitor maternal blood pressure, serum electrolytes (especially potassium, sodium, chloride), renal function (BUN, creatinine), and uric acid levels. Assess for signs of hyperkalemia or hyponatremia. Fetal monitoring includes serial ultrasound for growth and amniotic fluid volume due to diuretic effect. Neonatal monitoring for electrolyte disturbances and jaundice after delivery. |
| Fertility Effects | Spironolactone may cause antiandrogenic effects including menstrual irregularities, gynecomastia in males, and potential reversible impairment of fertility due to hormonal disruption. Hydrochlorothiazide has no known direct effects on fertility. In preclinical studies, spironolactone showed adverse effects on reproductive function. |