HYDROSERPINE PLUS (R-H-H)
Clinical safety rating: caution
Comprehensive clinical and safety monograph for HYDROSERPINE PLUS (R-H-H) (HYDROSERPINE PLUS (R-H-H)).
Hydrochlorothiazide inhibits the sodium-chloride symporter in the distal convoluted tubule, increasing excretion of sodium, chloride, and water. Reserpine depletes catecholamines from peripheral sympathetic nerve endings, reducing sympathetic tone. Hydralazine directly relaxes arteriolar smooth muscle, decreasing systemic vascular resistance.
| Metabolism | Hydrochlorothiazide: Not metabolized, excreted unchanged in urine. Reserpine: Metabolized in the liver via hydrolysis and conjugation. Hydralazine: Acetylation in the liver via N-acetyltransferase (NAT2). |
| Excretion | Hydroflumethiazide: renal (50-65% unchanged); reserpine: renal (30%) and fecal (60%) as metabolites; hydralazine: renal (85% as metabolites, 10% unchanged). |
| Half-life | Hydroflumethiazide: 2-3 h; reserpine: 50-100 h (biphasic); hydralazine: 2-4 h (fast acetylators), 6-8 h (slow acetylators). |
| Protein binding | Hydroflumethiazide: 70% (albumin); reserpine: 96%; hydralazine: 87% (albumin and alpha-1 acid glycoprotein). |
| Volume of Distribution | Hydroflumethiazide: 3.6 L/kg; reserpine: 10-20 L/kg; hydralazine: 1.6 L/kg (central) and 2.7 L/kg (total). |
| Bioavailability | Oral: hydroflumethiazide 70-75%; reserpine 50-60%; hydralazine 30-50% (first-pass metabolism). |
| Onset of Action | Oral: hydroflumethiazide 2 h; reserpine 3-6 days; hydralazine 45-60 min. |
| Duration of Action | Hydroflumethiazide: 6-12 h; reserpine: 1-6 weeks; hydralazine: 2-6 h (dose-dependent). |
1 tablet orally twice daily. Each tablet contains hydrochlorothiazide 25 mg, reserpine 0.125 mg, and hydralazine hydrochloride 25 mg.
| Dosage form | TABLET |
| Renal impairment | Contraindicated in severe renal impairment (CrCl <30 mL/min). For CrCl 30-50 mL/min: reduce dose to 1 tablet orally once daily; monitor electrolytes. No adjustment needed for CrCl >50 mL/min. |
| Liver impairment | Contraindicated in severe hepatic impairment (Child-Pugh class C). For Child-Pugh class A or B: use with caution; reduce dose to 1 tablet orally once daily and monitor for encephalopathy. |
| Pediatric use | Not recommended for pediatric use due to lack of safety and efficacy data. |
| Geriatric use | Start with 1 tablet orally once daily; titrate slowly. Monitor for orthostatic hypotension, electrolyte imbalances, and CNS effects. Avoid use in patients with depression. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for HYDROSERPINE PLUS (R-H-H) (HYDROSERPINE PLUS (R-H-H)).
| Breastfeeding | Hydrochlorothiazide is excreted in breast milk in low concentrations (M/P ratio 0.6); reserpine is excreted (M/P ratio unknown, but may cause galactorrhea and infant sedation); hydralazine is excreted in low amounts (M/P ratio not well defined). Theoretical risk of hypotensive effects in infants. Caution recommended. |
| Teratogenic Risk | First trimester: Hydrochlorothiazide is associated with an increased risk of neural tube defects and oral clefts; reserpine may cause respiratory distress; hydralazine is not teratogenic in animal studies. Second and third trimesters: Hydrochlorothiazide may cause fetal electrolyte disturbances and thrombocytopenia; reserpine may cause neonatal bradycardia and hypotension; hydralazine may cause fetal hypotension and reflex tachycardia. |
■ FDA Black Box Warning
Reserpine: May cause mental depression, especially in patients with a history of depression. Discontinue at first signs of depression.
| Serious Effects |
Reserpine: Hypersensitivity, history of depression, active peptic ulcer, ulcerative colitis, pheochromocytoma. Hydralazine: Hypersensitivity, mitral valve rheumatic heart disease, coronary artery disease. Hydrochlorothiazide: Anuria, hypersensitivity to sulfonamides, severe renal failure.
| Precautions | Hydrochlorothiazide: Electrolyte imbalance, hyperglycemia, hyperuricemia, lupus exacerbation. Reserpine: Mental depression, peptic ulcer, bradycardia. Hydralazine: Drug-induced lupus, tachycardia, myocardial ischemia, peripheral neuritis. |
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| Fetal Monitoring | Monitor maternal blood pressure, serum electrolytes (potassium, sodium), renal function, and uric acid; fetal growth and amniotic fluid volume via ultrasound; neonatal assessment for bradycardia, hypotension, and electrolyte imbalance after birth. |
| Fertility Effects | Hydrochlorothiazide may reduce libido and cause erectile dysfunction in males; reserpine may cause galactorrhea and menstrual irregularities; hydralazine has no known direct effect on fertility. Theoretical risk of reduced sperm motility due to antihypertensive effects. |