RESERPINE AND HYDROCHLOROTHIAZIDE
Clinical safety rating: safe
MAOIs can cause excitability and hypertension Can cause depression and suicidal ideation.
Reserpine is an adrenergic neuron blocking agent that depletes catecholamines and serotonin from central and peripheral neurons by inhibiting the vesicular monoamine transporter (VMAT). Hydrochlorothiazide is a thiazide diuretic that inhibits the sodium-chloride symporter in the distal convoluted tubule, reducing electrolyte resorption and causing diuresis.
| Metabolism | Reserpine is metabolized primarily by CYP3A4; Hydrochlorothiazide is not extensively metabolized (mostly excreted unchanged in urine). |
| Excretion | Reserpine: primarily renal (30-60% as metabolites, <1% unchanged) and fecal (40-60% via bile). Hydrochlorothiazide: predominantly renal (≥95% unchanged via glomerular filtration and tubular secretion). |
| Half-life | Reserpine: terminal half-life 50-100 hours (up to 11 days with chronic dosing due to tissue binding); clinically, antihypertensive effect persists for 1-6 weeks after discontinuation. Hydrochlorothiazide: terminal half-life 6-15 hours (mean ~9 hours); in renal impairment, half-life prolonged up to 24-40 hours. |
| Protein binding | Reserpine: approximately 96% bound to plasma proteins (primarily albumin). Hydrochlorothiazide: 65-70% bound to plasma proteins (mainly albumin). |
| Volume of Distribution | Reserpine: Vd 9.1 L/kg; extensive tissue distribution with high affinity for adipose tissue and brain. Hydrochlorothiazide: Vd 0.2-0.83 L/kg (mean ~0.55 L/kg); limited to extracellular fluid. |
| Bioavailability | Reserpine: oral bioavailability ~50% (extensive first-pass metabolism). Hydrochlorothiazide: oral bioavailability ~65-75% (range 50-80% due to saturable absorption). |
| Onset of Action | Reserpine: oral antihypertensive effect in 3-6 days; maximal effect in 3-6 weeks. Hydrochlorothiazide: oral diuresis begins within 2 hours, peak at 4-6 hours; antihypertensive effect in 2-3 days, maximal in 3-4 weeks. |
| Duration of Action | Reserpine: antihypertensive effect persists for 1-6 weeks after discontinuation due to irreversible binding. Hydrochlorothiazide: diuretic effect lasts ~6-12 hours; antihypertensive effect sustained for 24 hours with daily dosing. |
One tablet (0.125 mg reserpine and 25 mg hydrochlorothiazide) orally once daily. May be increased to two tablets once daily if needed. Maximum dose: 2 tablets (0.25 mg reserpine and 50 mg hydrochlorothiazide) per day.
| Dosage form | TABLET |
| Renal impairment | Contraindicated if GFR <30 mL/min. For GFR 30-60 mL/min: use with caution, monitor electrolytes, start at lowest dose. No dose adjustment specified for GFR >60 mL/min. |
| Liver impairment | Contraindicated in Child-Pugh class B or C. For Child-Pugh class A: use with caution, start at lowest dose, monitor for hepatic encephalopathy. No specific dose reduction quantified. |
| Pediatric use | Not recommended for use in pediatric patients due to lack of safety and efficacy data. |
| Geriatric use | Initiate at low end of dosing range (0.125 mg reserpine/25 mg hydrochlorothiazide once daily). Monitor for orthostatic hypotension, electrolyte imbalance, and renal function. Avoid if possible due to increased risk of adverse effects. |
| 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 breast milk; may cause extrapyramidal effects in infant. Hydrochlorothiazide also excreted; may suppress lactation. M/P ratio not well established. Contraindicated during breastfeeding. |
| Teratogenic Risk | First trimester: Reserpine crosses placenta; risk of fetal bradycardia, hypotonia, and hypothermia. Second/third trimester: Hydrochlorothiazide may cause fetal/neonatal electrolyte disturbances, jaundice, and thrombocytopenia. Use only if benefit outweighs risk. |
■ FDA Black Box Warning
None
| Common Effects | Depression |
| Serious Effects |
["History of depression, especially with suicidal tendencies.","Active peptic ulcer or ulcerative colitis.","Electroconvulsive therapy (ECT) within one week.","Hypersensitivity to reserpine, hydrochlorothiazide, or sulfonamide-derived drugs.","Anuria or severe renal impairment."]
| Precautions | ["Risk of depression, especially in patients with history; discontinue if signs appear.","May precipitate peptic ulcer disease; use cautiously in patients with history.","Electrolyte imbalances, including hypokalemia, hyponatremia, and hypomagnesemia.","Hyperuricemia may occur; monitor serum uric acid levels.","May cause drowsiness or dizziness; caution with driving/operating machinery."] |
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| Fetal Monitoring | Monitor maternal blood pressure, serum electrolytes (especially potassium, bicarbonate), renal function, and uric acid. Fetal monitoring for growth restriction, arrhythmias, and electrolyte imbalance via ultrasound and fetal heart rate. |
| Fertility Effects | Hydrochlorothiazide may cause gynecomastia and erectile dysfunction in males; reserpine may impair libido and induce galactorrhea. Both may reduce fertility potential transiently. |