RESERPINE AND HYDROFLUMETHIAZIDE
Clinical safety rating: safe
MAOIs can cause excitability and hypertension Can cause depression and suicidal ideation.
Reserpine irreversibly inhibits the vesicular monoamine transporter (VMAT2), depleting presynaptic stores of norepinephrine, dopamine, and serotonin in central and peripheral neurons, leading to reduced sympathetic outflow and decreased peripheral vascular resistance. Hydroflumethiazide is a thiazide diuretic that inhibits the sodium-chloride symporter (NCC) in the distal convoluted tubule, increasing excretion of sodium, chloride, and water, and reducing plasma volume and peripheral resistance.
| Metabolism | Reserpine is extensively metabolized in the liver by CYP2D6 and other enzymes; Hydroflumethiazide is not significantly metabolized, excreted unchanged in urine. |
| Excretion | Reserpine: renal (30% unchanged, 50% as metabolites), fecal (10%). Hydroflumethiazide: renal (>90% unchanged via organic anion transporter in proximal tubule), minimal biliary. |
| Half-life | Reserpine: 50-100 hours (terminal) due to prolonged neuronal binding, allowing once-daily dosing. Hydroflumethiazide: 6-15 hours (terminal), extended in renal impairment. |
| Protein binding | Reserpine: ~90-95% to albumin and α1-acid glycoprotein. Hydroflumethiazide: ~60-70% to albumin. |
| Volume of Distribution | Reserpine: 0.5-2 L/kg, extensive tissue binding (adrenergic neurons). Hydroflumethiazide: 1.2-3 L/kg, distributes to erythrocytes and tissues. |
| Bioavailability | Reserpine PO: 30-50% due to first-pass metabolism; consistent but variable. Hydroflumethiazide PO: ~65-75%. |
| Onset of Action | Reserpine PO: 3-6 days for full antihypertensive effect; initial effect within 1 week. Hydroflumethiazide PO: 2-3 hours for diuresis; 3-4 days for full antihypertensive effect. |
| Duration of Action | Reserpine: 1-6 weeks after discontinuation due to irreversible amine depletion. Hydroflumethiazide: 6-12 hours for diuresis; antihypertensive effect persists 12-24 hours. |
| Molecular Weight | 608.75 |
1 tablet (0.1 mg reserpine / 25 mg hydroflumethiazide) orally once daily. Dosage may be adjusted based on response; maximum reserpine 0.25 mg/day.
| Dosage form | TABLET |
| Renal impairment | GFR 30-60 mL/min: reduce dose by 50% of normal dose; GFR <30 mL/min: contraindicated (hydroflumethiazide ineffective, risk of azotemia). |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated due to risk of hepatic encephalopathy. |
| Pediatric use | Reserpine: 0.02 mg/kg/day orally in 1-2 divided doses (max 0.25 mg/day). Hydroflumethiazide: 1 mg/kg/day orally in 2 divided doses (max 2 mg/kg/day per dose). |
| Geriatric use | Start at half the standard dose (0.05 mg reserpine / 12.5 mg hydroflumethiazide) orally once daily; increase slowly based on BP response; monitor for orthostatic hypotension, electrolyte imbalances, and CNS depression. |
| 1st trimester | Reserpine crosses the placenta and is associated with increased risk of congenital malformations, including cardiovascular and CNS defects. Hydroflumethiazide is a thiazide diuretic; use in first trimester is not recommended due to potential teratogenic effects. Avoid use unless no alternative. |
| 2nd trimester | Reserpine can cause neonatal respiratory depression, bradycardia, and nasal congestion. Hydroflumethiazide may cause electrolyte imbalances in the mother and fetus. Use only if clearly needed and benefits outweigh risks. |
| 3rd trimester | Reserpine may cause neonatal respiratory depression, bradycardia, and nasal congestion due to catecholamine depletion. Hydroflumethiazide can cause fetal electrolyte disturbances, jaundice, and thrombocytopenia. Avoid in third trimester near term. |
Clinical note
MAOIs can cause excitability and hypertension Can cause depression and suicidal ideation.
| FDA category | Animal |
| Placental transfer |
■ FDA Black Box Warning
None
| Common Effects | Depression |
| Serious Effects |
Hypersensitivity to reserpine or hydroflumethiazideHistory of mental depression (especially with suicidal tendencies)Active peptic ulcerUlcerative colitisElectroconvulsive therapy (within 7 days)AnuriaRenal failureSevere hepatic impairment
| Precautions | Risk of depression, suicide, or exacerbation of psychiatric disorders; bradycardia and orthostatic hypotension; electrolyte imbalances (hypokalemia, hyponatremia, hypomagnesemia, hypocalcemia) and volume depletion; increased serum uric acid and precipitation of gout; increased blood glucose and impaired glucose tolerance; systemic lupus erythematosus exacerbation; abrupt withdrawal may precipitate hypertensive crisis. |
| Food/Dietary | Avoid foods high in sodium (processed foods, canned soups) as they can reduce antihypertensive effect. Increase intake of potassium-rich foods (bananas, oranges, potatoes) unless contraindicated. Limit alcohol and caffeine. Avoid tyramine-rich foods (aged cheeses, cured meats) due to reserpine's MAO inhibition potential. |
Loading safety data…
| Reserpine crosses the placenta extensively; hydroflumethiazide crosses the placenta and enters fetal circulation. Both achieve fetal concentrations similar to maternal levels. |
| Breastfeeding | Reserpine is excreted into breast milk and may cause adverse effects in nursing infants, including respiratory depression, bradycardia, and nasal congestion. Hydroflumethiazide is excreted in breast milk in small amounts; however, thiazides can suppress lactation. Avoid breastfeeding during therapy. |
| Lactation Rating | Avoid |
| Teratogenic Risk | First trimester: Reserpine crosses placenta; association with congenital malformations not definitively established but risk cannot be excluded. Hydroflumethiazide: No adequate studies; thiazides may cause fetal or neonatal jaundice, thrombocytopenia, and electrolyte disturbances. Second and third trimesters: Reserpine may cause neonatal respiratory depression, bradycardia, hypothermia, and nasal congestion. Hydroflumethiazide may cause fetal or neonatal jaundice, thrombocytopenia, and electrolyte imbalances. Use only if benefit outweighs risk. |
| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and electrolytes (sodium, potassium). Monitor fetal growth and well-being via ultrasound and non-stress testing. Assess for signs of neonatal depression, bradycardia, hypothermia, and jaundice postpartum. Monitor infant for electrolyte imbalances and thrombocytopenia if exposed in utero. |
| Fertility Effects | Reserpine may cause decreased libido, impotence, and menstrual irregularities in women; may suppress reproductive function. Hydroflumethiazide has no direct effect on fertility but electrolyte disturbances may indirectly affect reproductive function. No evidence of permanent impairment. |
| Clinical Pearls | Reserpine depletes catecholamines centrally and peripherally, potentially causing depression and nasal congestion. Hydroflumethiazide is a thiazide diuretic; monitor electrolytes, especially potassium and magnesium. Use with caution in patients with history of peptic ulcer or depression. Combine with NSAIDs may reduce antihypertensive effect. |
| Patient Advice | Take this medication exactly as prescribed, usually once daily. · Do not stop taking abruptly; may cause severe hypertension. · May cause dizziness or drowsiness; avoid driving until you know how it affects you. · Avoid alcohol and other CNS depressants. · Report any signs of depression, mood changes, or suicidal thoughts. · Monitor for signs of electrolyte imbalance: muscle cramps, weakness, irregular heartbeat. · This drug depletes potassium; consider potassium-rich foods or supplements as advised. · May cause nasal congestion; discuss if bothersome. · Stay hydrated unless otherwise directed by your doctor. · Avoid prolonged sun exposure; use sunscreen. |