RESERPINE AND HYDROCHLOROTHIAZIDE-50
Clinical safety rating: safe
MAOIs can cause excitability and hypertension Can cause depression and suicidal ideation.
Reserpine irreversibly inhibits the vesicular monoamine transporter 2 (VMAT2), depleting presynaptic stores of catecholamines (norepinephrine, dopamine, serotonin) in central and peripheral neurons, leading to reduced sympathetic outflow. Hydrochlorothiazide is a thiazide-type diuretic that inhibits the sodium-chloride symporter in the distal convoluted tubule, increasing sodium, chloride, and water excretion, thereby reducing plasma volume and cardiac output.
| Metabolism | Reserpine is extensively metabolized via hepatic CYP450 enzymes (primarily CYP3A4) to inactive metabolites. Hydrochlorothiazide undergoes minimal hepatic metabolism; most is excreted unchanged in urine. |
| Excretion | Reserpine: renal (30% as metabolites, <1% unchanged); fecal (60% as metabolites). Hydrochlorothiazide: renal (≥95% unchanged via active tubular secretion). |
| Half-life | Reserpine: 50-100 hours (biphasic, terminal half-life 4.5-11 days due to enterohepatic recirculation). Hydrochlorothiazide: 6-15 hours (increased in renal impairment). |
| Protein binding | Reserpine: ~96% bound to plasma proteins (mainly albumin and alpha-1 acid glycoprotein). Hydrochlorothiazide: 68% bound to albumin. |
| Volume of Distribution | Reserpine: 7.5-8.5 L/kg (extensive tissue binding, especially adipose and brain). Hydrochlorothiazide: 3-5 L/kg (distributes into erythrocytes). |
| Bioavailability | Reserpine: oral 50% (variable due to first-pass metabolism). Hydrochlorothiazide: oral 65-75% (reduced with food). |
| Onset of Action | Reserpine: oral 3-6 hours (antihypertensive effect). Hydrochlorothiazide: oral 2 hours (diuresis). |
| Duration of Action | Reserpine: oral 6-24 hours (antihypertensive). Hydrochlorothiazide: oral 6-12 hours (diuresis). |
1 tablet (containing 0.1 mg reserpine and 50 mg hydrochlorothiazide) orally once daily; may increase to 2 tablets daily in divided doses if needed.
| Dosage form | TABLET |
| Renal impairment | Hydrochlorothiazide: Contraindicated if GFR <30 mL/min; for GFR 30–50 mL/min, use reduced dose (e.g., 25 mg hydrochlorothiazide component) or alternative. Reserpine: No specific adjustment, but use caution if severe impairment. |
| Liver impairment | Reserpine (Child-Pugh A or B): No specific adjustment; Child-Pugh C: Avoid due to risk of hepatic encephalopathy. Hydrochlorothiazide (Child-Pugh A or B): Use caution; Child-Pugh C: Avoid due to risk of electrolyte disturbances and hypokalemia precipitating encephalopathy. |
| Pediatric use | Not typically recommended; if used, reserpine dose: 0.02–0.25 mg/kg/day in 1–2 divided doses (max 5 mg/day); hydrochlorothiazide dose: 2–3 mg/kg/day in 2 divided doses (max 50 mg/day). Base on weight. |
| Geriatric use | Start with 0.5 tablet (0.05 mg reserpine/25 mg hydrochlorothiazide) once daily; monitor for orthostatic hypotension, electrolyte imbalance, and CNS depression. Adjust slowly. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
MAOIs can cause excitability and hypertension Can cause depression and suicidal ideation.
| FDA category | Animal |
| Breastfeeding | Reserpine is excreted in human milk; M/P ratio not established. Hydrochlorothiazide is excreted in low amounts; M/P ratio approximately 0.2. Infant exposure is low but reserpine may cause drowsiness, diarrhea, or nasal congestion in breastfeeding infant. Avoid use while breastfeeding due to potential adverse effects. |
| Teratogenic Risk |
■ FDA Black Box Warning
None
| Common Effects | Depression |
| Serious Effects |
["Hypersensitivity to reserpine, hydrochlorothiazide, or other sulfonamide-derived drugs","Anuria","Active peptic ulcer or history of peptic ulcer disease (because of reserpine)","Ulcerative colitis (because of reserpine)","Electroconvulsive therapy (within 7 days) (because of reserpine)","Concurrent MAO inhibitor therapy"]
| Precautions | ["May cause mental depression, especially at higher doses; discontinue if signs of depression appear.","Electrolyte imbalances (hypokalemia, hyponatremia, hypomagnesemia, hypercalcemia) with hydrochlorothiazide; monitor electrolytes.","Sulfonamide-related hypersensitivity reactions; cross-sensitivity with other sulfonamides possible.","May precipitate gout or hyperuricemia; monitor uric acid.","Use caution in patients with renal impairment; avoid in anuria.","May increase lithium toxicity; monitor lithium levels.","Reserpine may cause bradycardia, orthostatic hypotension, and nasal congestion."] |
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| First trimester: Reserpine crosses placenta; risk of congenital malformations not established but animal studies show fetal harm. Hydrochlorothiazide associated with neural tube defects in early pregnancy. Second trimester: Risk of fetal bradycardia with reserpine; diuretic use may reduce placental perfusion. Third trimester: Reserpine may cause neonatal respiratory depression, bradycardia, hypothermia, and nasal congestion. Hydrochlorothiazide can cause electrolyte disturbances in neonate. |
| Fetal Monitoring | Monitor maternal blood pressure closely, avoid hypotension. Check maternal serum electrolytes (sodium, potassium) regularly due to thiazide. Assess fetal growth via ultrasound for potential intrauterine growth restriction. Monitor fetal heart rate for bradycardia. In third trimester, assess neonatal for symptoms of reserpine withdrawal. |
| Fertility Effects | Reserpine may cause hyperprolactinemia, leading to decreased libido, menstrual irregularities, and impaired fertility. Hydrochlorothiazide has no known direct effect on fertility. |