DRALZINE
Clinical safety rating
cautionComprehensive 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. |
| Molecular Weight | 285.3 |
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 | Avoid use in first trimester unless clearly needed. Animal studies suggest risk of teratogenicity, but no controlled human data. |
| 2nd trimester | Use only if potential benefit justifies potential risk. May cause fetal hypotension and impaired placental perfusion. |
| 3rd trimester | Use cautiously; limited evidence of harm. Monitor for maternal hypotension and fetal distress. |
Clinical note
Comprehensive clinical and safety monograph for DRALZINE (DRALZINE).
| Placental transfer | Crosses placenta; detectable in fetal plasma at concentrations similar to maternal levels. |
| Breastfeeding | Excreted in breast milk in low amounts; no adverse effects reported in infants. However, use with caution due to potential for hypotension and drug accumulation in neonates. |
| Lactation Rating | L3 - Moderately Safe |
| 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 | 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. |
■ FDA Black Box Warning
None.
| Serious Effects |
Hypersensitivity to hydralazineCoronary artery diseaseMitral valve rheumatic heart disease
| 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. |
| Food/Dietary | DRALZINE should be taken with or without food, but consistent timing is recommended. High-tyramine foods (e.g., aged cheeses, cured meats, fermented products) may increase the risk of hypertensive crisis in patients also taking MAOIs; however, interactions with food are otherwise minimal. Avoid large, high-fat meals as they may affect absorption. |
| Clinical Pearls | DRALZINE (hydralazine) is a direct-acting vasodilator used primarily for hypertension, especially in pregnancy (pre-eclampsia). It can cause a drug-induced lupus-like syndrome, especially in slow acetylators; monitor for arthralgias, rash, and positive ANA. Tachycardia is a common reflex response; often co-administered with a beta-blocker. Avoid in patients with coronary artery disease, high-output heart failure, or mitral valve rheumatic heart disease. |
| Patient Advice | Take exactly as prescribed; do not skip doses or double up. · You may experience dizziness or lightheadedness, especially when standing up; rise slowly and avoid sudden position changes. · Report any joint pain, rash, fever, or chest pain to your healthcare provider immediately. · Avoid alcohol, which can worsen side effects like dizziness and low blood pressure. · Do not stop taking this medication abruptly; sudden withdrawal can cause a rapid increase in blood pressure. |
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