HYSERPIN
Clinical safety rating
cautionComprehensive clinical and safety monograph for HYSERPIN (HYSERPIN).
Hyserpin is a combination of reserpine and hydralazine. Reserpine depletes catecholamines and serotonin from nerve endings by inhibiting vesicular monoamine transporter (VMAT). Hydralazine is a direct arteriolar vasodilator that reduces peripheral resistance via relaxation of vascular smooth muscle, possibly through nitric oxide-mediated pathways.
| Metabolism | Reserpine: extensively metabolized in the liver via cytochrome P450 enzymes; hydralazine: primarily metabolized by N-acetylation (polymorphic) and oxidation. |
| Excretion | Renal: 50-60% unchanged; biliary/fecal: 30-40% as metabolites |
| Half-life | Terminal elimination half-life: 12-16 hours; clinical context: supports twice-daily dosing for hypertension |
| Protein binding | 85-93%; primarily bound to albumin and alpha-1-acid glycoprotein |
| Volume of Distribution | 2-4 L/kg; indicates extensive tissue distribution, higher in hypertensive patients |
| Bioavailability | Oral: 50-60%; intramuscular: 70-80% |
| Onset of Action | Oral: 30-60 minutes; Intravenous: 5-10 minutes; Intramuscular: 15-30 minutes |
| Duration of Action | Oral: 6-12 hours; intravenous/intramuscular: 4-8 hours; prolonged with renal impairment |
| Molecular Weight | Reserpine: 608.68 Da; Hydralazine: 160.18 Da; Hydrochlorothiazide: 297.74 Da |
Oral: 0.1-0.25 mg twice daily. Maximum dose: 0.5 mg daily.
| Dosage form | TABLET |
| Renal impairment | Not dialyzable. No specific GFR-based adjustments; use with caution in severe impairment. |
| Liver impairment | Child-Pugh Class B or C: reduce dose by 50% or increase dosing interval (e.g., once daily). |
| Pediatric use | Not recommended due to lack of safety and efficacy data. Avoid in children. |
| Geriatric use | Initiate at 0.05 mg once daily; titrate slowly to minimize hypotension and CNS effects. |
| 1st trimester | Hypertension is a combination product containing reserpine, hydralazine, and hydrochlorothiazide. Reserpine crosses the placenta and may cause adverse effects; hydralazine is associated with maternal hypotension and potential fetal hypoxia; hydrochlorothiazide may cause electrolyte imbalances and decreased placental perfusion. Avoid in first trimester. |
| 2nd trimester | Use only if clearly needed; all components have potential fetal risks. Monitor maternal blood pressure closely. |
| 3rd trimester | Avoid near term due to risk of neonatal thrombocytopenia from hydrochlorothiazide, and potential neonatal bradycardia from reserpine. |
Clinical note
Comprehensive clinical and safety monograph for HYSERPIN (HYSERPIN).
| Placental transfer | Reserpine and hydralazine cross the placenta; hydrochlorothiazide crosses the placenta. All three components have documented placental transfer. |
| Breastfeeding | Reserpine is excreted into breast milk and may cause galactorrhea, sedation, and respiratory depression in the infant. Hydralazine and hydrochlorothiazide are also excreted; thiazides may decrease milk production. Avoid breastfeeding. |
| Lactation Rating | L5 - Contraindicated |
| Teratogenic Risk | Hypertension itself poses risks to the fetus (e.g., placental insufficiency, growth restriction). For antihypertensives in general: first trimester: no major teratogenicity known for most agents; second/third trimester: risk of fetal hypotension, hypoxia, and growth restriction. Specific to Hyserpin (reserpine): animal studies show possible teratogenic effects; human data limited. Avoid in pregnancy especially third trimester due to risk of neonatal bradycardia, hypothermia, and nasal congestion. |
| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and signs of depression (potential adverse effect). Fetal monitoring: ultrasound for growth, non-stress test or biophysical profile in third trimester if chronic hypertension. |
| Fertility Effects | Reserpine may impair fertility in males due to decreased libido and possible impairment of sexual function. No specific human studies on female fertility; theoretical effect on reproductive hormones (catecholamine depletion). |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to any componentActive peptic ulcer diseaseUlcerative colitisHistory of depression (especially with reserpine)Electroconvulsive therapySevere renal impairment (anuria)Severe hepatic impairmentHypersensitivity to sulfonamide-derived drugs (hydrochlorothiazide)
| Precautions | Risk of mental depression (reserpine), Orthostatic hypotension, Lupus-like syndrome (hydralazine, especially in slow acetylators), Peripheral neuropathy (hydralazine, due to pyridoxine deficiency) |
| Food/Dietary | Avoid excessive intake of tyramine-rich foods (aged cheeses, cured meats, pickled herring, broad beans, soybean products) due to potential hypertensive crisis risk with reserpine. Avoid licorice (glycyrrhiza) as it can worsen hypokalemia induced by hydrochlorothiazide. Limit salt substitutes containing potassium; monitor potassium levels. Avoid grapefruit juice as it may increase reserpine bioavailability. Take with food or milk to reduce gastrointestinal upset. |
| Clinical Pearls | Hyserpin is a combination product of reserpine and hydrochlorothiazide. Reserpine depletes catecholamines, causing bradycardia and orthostatic hypotension; start with low doses and monitor BP closely. Hydrochlorothiazide can cause hypokalemia, hyponatremia, and hyperglycemia; check electrolytes and renal function at baseline and periodically. Avoid use in patients with history of depression, peptic ulcer, or ulcerative colitis due to reserpine. May cause nasal congestion and drowsiness. Use with caution in patients on MAOIs or digitalis. |
| Patient Advice | Take exactly as prescribed; do not skip doses or stop suddenly. · Rise slowly from sitting or lying down to prevent dizziness. · Avoid alcohol and other sedatives as they may increase drowsiness. · Report weight gain, swelling, or shortness of breath (signs of fluid overload). · May cause nasal stuffiness or vivid dreams; if bothersome, notify your doctor. · Do not use over-the-counter cold or appetite suppressants without consulting your doctor. · May cause sensitivity to sunlight; use sunscreen and protective clothing. · Regular monitoring of blood pressure and lab tests (potassium, glucose) is essential. |
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