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. |
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 | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for UNITENSEN (UNITENSEN).
| Breastfeeding | Excreted in human milk; M/P ratio unknown. Avoid breastfeeding due to potential for adverse effects in the infant, including hypotension and renal impairment. |
| 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 |
■ 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 hydralazine or any component of the formulation; coronary artery disease (due to risk of reflex tachycardia and myocardial ischemia); mitral valvular rheumatic heart disease (may increase pulmonary artery pressure).
| 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). |
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| 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. |