UNITENSEN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for UNITENSEN (UNITENSEN).
Direct-acting vasodilator that relaxes arteriolar smooth muscle, reducing peripheral vascular resistance and lowering blood pressure. The exact mechanism is unclear but may involve interference with calcium influx across vascular smooth muscle cell membranes.
| Metabolism | Extensively metabolized in the liver via N-acetylation (polymorphic NAT2 enzyme) and hydroxylation, followed by glucuronidation. Citrulline is a minor metabolite. Oral bioavailability is increased in slow acetylators. |
| Excretion | Primarily renal (40-60% unchanged drug), biliary/fecal (20-30% as metabolites). |
| Half-life | Terminal elimination half-life is 12-15 hours; prolonged in renal impairment (up to 35 hours). |
| Protein binding | 85-95% bound primarily to albumin. |
| Volume of Distribution | 0.3-0.5 L/kg, indicating distribution mainly in extracellular fluid. |
| Bioavailability | Oral: 70-85% due to first-pass metabolism. |
| Onset of Action | Oral: 1-2 hours; Intravenous: 5-15 minutes. |
| Duration of Action | Oral: 12-24 hours; Intravenous: 6-12 hours; duration extended in renal dysfunction. |
| Molecular Weight | 591.68 Da |
Oral: 2.5 mg once daily, may increase to 5 mg once daily after 2 weeks if needed.
| Dosage form | INJECTABLE |
| Renal impairment | GFR 30-89 mL/min: 2.5 mg once daily; GFR <30 mL/min: not recommended. |
| Liver impairment | Child-Pugh A: 2.5 mg once daily; Child-Pugh B or C: not recommended. |
| Pediatric use | Not established; safety and efficacy in pediatric patients have not been studied. |
| Geriatric use | Start at 2.5 mg once daily; titrate cautiously due to increased sensitivity and renal impairment. |
| 1st trimester | Contraindicated due to risk of fetal hypotension, oligohydramnios, and renal impairment. May cause skull defects. |
| 2nd trimester | Contraindicated due to risk of fetal toxicity, including oligohydramnios and renal failure. |
| 3rd trimester | Contraindicated due to risk of neonatal hypotension, anuria, hyperkalemia, and skull hypoplasia. |
Clinical note
Comprehensive clinical and safety monograph for UNITENSEN (UNITENSEN).
| Placental transfer | Crosses placenta; detected in fetal plasma and amniotic fluid. Associated with fetal toxicity. |
| Breastfeeding | Excreted into breast milk in low concentrations; however, potential for adverse effects in nursing infants, especially hypotension. Use with caution, monitor infant for hypotension and renal function. |
■ FDA Black Box Warning
Lupus-like syndrome: Use of hydralazine, the active component of Unitensen, has been associated with a drug-induced lupus erythematosus-like syndrome, particularly in slow acetylators and at higher doses. Symptoms include arthralgia, myalgia, rash, fever, and serositis. Discontinue hydralazine if lupus-like symptoms develop.
| Serious Effects |
Hypersensitivity to drug or excipientsPregnancy (especially second and third trimesters)History of angioedema with prior ACE inhibitor therapyRenal artery stenosis (bilateral or unilateral to solitary kidney)Concomitant use with aliskiren in patients with diabetes or moderate-severe renal impairment (GFR <60 mL/min)Hyperkalemia refractory to therapy
| Precautions | May cause a lupus-like syndrome, especially in slow acetylators; monitor for symptoms. Can precipitate angina or myocardial infarction in patients with coronary artery disease due to reflex tachycardia. Use with caution in patients with cerebrovascular disease, severe renal impairment, or pre-existing hypotension. Hematologic adverse effects (e.g., neutropenia, agranulocytosis) have been reported rarely; monitor CBC periodically. Peripheral neuritis may occur (possibly due to pyridoxine deficiency). |
Loading safety data…
| Lactation Rating |
| L4 (Possibly hazardous) |
| Teratogenic Risk | First trimester: Risk of congenital malformations based on animal studies; limited human data suggest possible association with fetal anomalies. Second and third trimesters: Fetal hypotension, renal impairment, oligohydramnios, and skull ossification defects. |
| Fetal Monitoring | Monitor maternal blood pressure, renal function, and electrolytes. Fetal monitoring includes ultrasound for oligohydramnios and fetal growth, and fetal heart rate monitoring. |
| Fertility Effects | No data on human fertility; animal studies show no impairment. Theoretical risk due to antihypertensive effects on reproductive organ perfusion. |
| Food/Dietary |
| Avoid grapefruit juice as it may increase drug levels. Limit alcohol intake due to additive hypotensive effects. No specific food restrictions otherwise. |
| Clinical Pearls | Unitensen (cryptenamine tannate) is a veratrum alkaloid used historically for hypertension. Monitor for bradycardia, hypotension, and emesis; dose titration is critical. Avoid in patients with coronary insufficiency or recent MI. Onset is rapid, and effects are dose-dependent. |
| Patient Advice | Take this medication exactly as prescribed; do not increase the dose without consulting your doctor. · Report any severe nausea, vomiting, or dizziness immediately, as these may indicate overdose. · Avoid alcohol and grapefruit juice, as they may enhance hypotensive effects. · Rise slowly from sitting or lying positions to prevent fainting. · Keep a record of your blood pressure and heart rate to share with your healthcare provider. |