SERPASIL-ESIDRIX #2
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SERPASIL-ESIDRIX #2 (SERPASIL-ESIDRIX #2).
Serpasil-Esidrix #2 contains reserpine and hydrochlorothiazide. Reserpine irreversibly inhibits the vesicular monoamine transporter 2 (VMAT2) in the CNS and peripheral sympathetic nerve endings, depleting norepinephrine, dopamine, and serotonin from storage vesicles, leading to reduced sympathetic outflow and antihypertensive effect. Hydrochlorothiazide inhibits the Na+/Cl- cotransporter in the distal renal tubule, increasing excretion of sodium, chloride, and water, thereby reducing plasma volume and peripheral vascular resistance.
| Metabolism | Reserpine is extensively metabolized in the liver via hydrolysis and conjugation, with metabolites excreted in urine and feces. Hydrochlorothiazide is not metabolized extensively; it is primarily eliminated unchanged by the kidneys. |
| Excretion | Reserpine: 60% renal (as metabolites), 40% fecal (as parent drug and metabolites); Hydrochlorothiazide: >95% renal (unchanged) via tubular secretion. |
| Half-life | Reserpine: 50-100 hours (biphasic; terminal phase 11-16 days due to slow release from adrenergic storage sites); Hydrochlorothiazide: 6-15 hours (prolonged in renal impairment). |
| Protein binding | Reserpine: 96% bound to albumin; Hydrochlorothiazide: 40-68% bound to albumin. |
| Volume of Distribution | Reserpine: 5-8 L/kg (extensive tissue binding, particularly to adrenergic neurons); Hydrochlorothiazide: 0.83-1.14 L/kg (distributes into extracellular fluid). |
| Bioavailability | Reserpine: 50-60% (oral, extensive first-pass metabolism); Hydrochlorothiazide: 65-75% (oral, with food decreasing absorption by 10-20%). |
| Onset of Action | Reserpine: 3-6 hours (oral); Hydrochlorothiazide: 2 hours (oral) for diuretic effect, 3-4 hours for antihypertensive effect. |
| Duration of Action | Reserpine: 1-4 weeks (depletion of catecholamines persists after discontinuation); Hydrochlorothiazide: 6-12 hours (diuretic effect), 24 hours (antihypertensive effect with chronic dosing). |
1 tablet orally once daily. Each tablet contains 0.25 mg reserpine and 50 mg hydrochlorothiazide.
| Dosage form | TABLET |
| Renal impairment | Contraindicated if GFR < 30 mL/min. For GFR 30-59 mL/min, maximum dose is 1 tablet every other day due to hydrochlorothiazide accumulation. |
| Liver impairment | Child-Pugh A: caution, consider reducing dose. Child-Pugh B: contraindicated due to risk of hepatic coma and reserpine-induced depression. Child-Pugh C: contraindicated. |
| Pediatric use | Not recommended for children. Safety and efficacy not established. |
| Geriatric use | Initiate with 0.5 tablet once daily due to increased sensitivity to reserpine (CNS depression) and hydrochlorothiazide (hypotension, electrolyte imbalance). Titrate slowly. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for SERPASIL-ESIDRIX #2 (SERPASIL-ESIDRIX #2).
| Breastfeeding | Reserpine is excreted into breast milk; M/P ratio not established. Potential for severe adverse effects in nursing infants including respiratory depression, bradycardia, and hypotonia. Hydrochlorothiazide is excreted in breast milk in low amounts (M/P ratio approximately 0.4-0.5), but may suppress lactation and cause electrolyte disturbances. Avoid breastfeeding during therapy. |
| Teratogenic Risk | Serpasil (reserpine) is classified as FDA Pregnancy Category C. Reserpine crosses the placenta. First trimester: Limited human data, but animal studies suggest increased risk of skeletal and cardiovascular anomalies. Second and third trimesters: Possible adverse effects including neonatal respiratory depression, bradycardia, hypothermia, and hypotonia. Esidrix (hydrochlorothiazide) is FDA Pregnancy Category B; however, thiazide diuretics may cause fetal or neonatal jaundice, thrombocytopenia, and electrolyte disturbances. Use only if clearly needed. |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to reserpine, hydrochlorothiazide, or sulfonamides.","History of mental depression or suicidal tendencies.","Active peptic ulcer or ulcerative colitis.","Electroconvulsive therapy (ECT) within 7 days.","Anuria or severe renal impairment (e.g., creatinine clearance <30 mL/min).","Pheochromocytoma (reserpine may paradoxically increase blood pressure)."]
| Precautions | ["Reserpine may cause depression, and should be discontinued if symptoms occur; use with caution in patients with history of depression.","Hydrochlorothiazide may cause electrolyte imbalances (e.g., hypokalemia), dehydration, and increased serum uric acid and glucose.","May cause orthostatic hypotension, especially with alcohol or other antihypertensives.","Renal impairment: monitor renal function.","Hepatic impairment: use with caution as reserpine may precipitate hepatic encephalopathy.","Sulfonamide allergy: hydrochlorothiazide is a sulfonamide derivative; cross-sensitivity may occur.","May require dosage adjustment in renal impairment.","Avoid abrupt discontinuation of reserpine; taper gradually."] |
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| Fetal Monitoring | Maternal: Monitor blood pressure, heart rate, serum electrolytes (sodium, potassium, chloride), renal function, and signs of depression or sedation. Fetal: Monitor fetal growth and amniotic fluid volume via ultrasound, especially with hydrochlorothiazide due to risk of oligohydramnios; assess neonatal for respiratory depression and bradycardia at delivery. Consider fetal heart rate monitoring if reserpine used near term. |
| Fertility Effects | Reserpine may cause decreased libido, impotence in males, and potential reversible galactorrhea or menstrual irregularities in females. Hydrochlorothiazide has no established direct effect on fertility. Combined product may impair reproductive function via hormonal and autonomic effects. |