SERPASIL-ESIDRIX #2
Clinical safety rating
cautionComprehensive 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). |
| Molecular Weight | Reserpine: 608.68 Da; Hydrochlorothiazide: 297.73 Da |
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 | First trimester: Risk of fetal harm cannot be ruled out. Reserpine crosses the placenta and may cause adverse effects. Use only if clearly needed. |
| 2nd trimester | Second trimester: Similar risks as first trimester. Monitor fetal growth and amniotic fluid index. |
| 3rd trimester | Third trimester: Reserpine may cause neonatal effects such as bradycardia, hypotonia, and nasal congestion. Hydrochlorothiazide may cause fetal or neonatal jaundice, thrombocytopenia. Avoid near term. |
Clinical note
Comprehensive clinical and safety monograph for SERPASIL-ESIDRIX #2 (SERPASIL-ESIDRIX #2).
| Placental transfer | Reserpine crosses the placenta and is detected in fetal tissues. Hydrochlorothiazide crosses the placenta and is distributed in fetal plasma. |
| Breastfeeding | Reserpine is excreted into breast milk and may cause adverse effects in nursing infants, including nasal congestion, increased respiratory secretions, and bradycardia. Hydrochlorothiazide is excreted in low amounts but may suppress lactation. Avoid breastfeeding during therapy or use with caution. |
| Lactation Rating | L4 (Possibly Hazardous) |
| 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. |
| 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. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to reserpine, hydrochlorothiazide, or sulfonamide derivativesHistory of mental depression (especially with suicidal tendencies)Active peptic ulcerUlcerative colitisElectroconvulsive therapy (within 1 week)AnuriaSevere renal impairment (CrCl <30 mL/min)Hepatic coma or pre-coma
| 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. |
| Food/Dietary | High-potassium foods (bananas, oranges, spinach) may increase risk of hyperkalemia if used with potassium-sparing diuretics; however, hydrochlorothiazide is potassium-wasting, so hypokalemia risk exists. Avoid excessive sodium intake (processed foods, salt) as it can reduce antihypertensive effect. Grapefruit juice may interact with reserpine; limit consumption. |
| Clinical Pearls | Serpasil (reserpine) plus Esidrix (hydrochlorothiazide) #2 is a fixed-dose combination for hypertension. Reserpine depletes catecholamines: monitor for depression, nasal congestion, sedation, and bradycardia. Hydrochlorothiazide: check electrolytes, uric acid, glucose; avoid in anuria. Onset of reserpine action is slow (weeks) but prolonged (weeks after discontinuation). Combination may exacerbate gout and diabetes. |
| Patient Advice | Take exactly as prescribed; do not stop suddenly as high blood pressure may worsen. · May cause drowsiness or dizziness; avoid driving or operating heavy machinery until effects are known. · Avoid alcohol as it can increase dizziness and drowsiness. · Report symptoms of depression, slow heart rate, severe nasal congestion, or unusual bleeding/bruising. · Use sun protection as hydrochlorothiazide increases sun sensitivity. · Monitor for signs of electrolyte imbalance: muscle cramps, weakness, irregular heartbeat, excessive thirst. · Inform all healthcare providers you are taking this medication, especially before surgery. |
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