DRALZINE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for DRALZINE (DRALZINE).
Dralzine is a direct-acting arteriolar vasodilator that relaxes vascular smooth muscle, leading to decreased systemic vascular resistance and afterload. The exact molecular mechanism is not fully elucidated but involves inhibition of calcium influx and interference with the contractile process.
| Metabolism | Primarily hepatic via N-acetyltransferase (NAT2); exhibits polymorphic acetylation. Metabolites include hydralazine pyruvate hydrazone and other hydrazone derivatives. |
| Excretion | Primarily renal (70-90% as unchanged drug and metabolites); biliary/fecal excretion accounts for <10%. |
| Half-life | Terminal elimination half-life is 2-5 hours in patients with normal renal function; prolonged to 10-20 hours in renal impairment. |
| Protein binding | 85-90%, primarily to albumin. |
| Volume of Distribution | 1.5-2.0 L/kg; indicates extensive tissue distribution, exceeding total body water. |
| Bioavailability | Oral: 30-50% due to first-pass metabolism. |
| Onset of Action | Intravenous: 10-20 minutes; Oral: 30-60 minutes. |
| Duration of Action | 2-6 hours depending on dose and route; intravenous effects may be shorter than oral. |
Oral: 50-100 mg twice daily; maximum 200 mg/day.
| Dosage form | TABLET |
| Renal impairment | GFR 10-50 mL/min: 50 mg twice daily; GFR <10 mL/min: 50 mg once daily. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: 50 mg twice daily; Child-Pugh C: avoid use. |
| Pediatric use | 1-2 mg/kg/day divided every 12 hours; maximum 5 mg/kg/day. |
| Geriatric use | Initiate at 25 mg twice daily; titrate slowly to avoid hypotension. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for DRALZINE (DRALZINE).
| Breastfeeding | Compatible with breastfeeding. M/P ratio not established; drug appears in breast milk in low amounts (<1% maternal dose). No reported adverse effects in infants. |
| Teratogenic Risk | First trimester: No evidence of teratogenicity in human studies; however, consider fetal hypotension and impaired uteroplacental perfusion. Second and third trimesters: Risk of fetal hypotension, adverse fetal heart rate patterns, and neonatal adverse effects (hypotension, tachycardia, fluid retention). |
| Fetal Monitoring |
■ FDA Black Box Warning
None.
| Serious Effects |
["Hypersensitivity to hydralazine or components","Coronary artery disease (relative contraindication due to risk of myocardial ischemia)","Mitral valve rheumatic heart disease (relative)","Idiopathic lupus erythematosus"]
| Precautions | ["May induce a lupus-like syndrome, especially in slow acetylators; monitor for symptoms such as arthralgia, fever, and rash.","May cause drug-induced autoimmune hepatitis.","Can precipitate angina or myocardial infarction in patients with coronary artery disease.","Risk of hypotension and reflex tachycardia."] |
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| Maternal: Blood pressure, heart rate, complete blood count, antinuclear antibody (ANA) titer, and hepatic function. Fetal/neonatal: Fetal heart rate monitoring during labor, neonatal blood pressure monitoring for first 24 hours. |
| Fertility Effects | No known adverse effects on human fertility. Animal studies show no reproductive impairment. |