NORMOZIDE
Clinical safety rating
cautionComprehensive clinical and safety monograph for NORMOZIDE (NORMOZIDE).
Normozide is a combination of prazosin and polythiazide. Prazosin blocks alpha-1 adrenergic receptors, causing vasodilation and reduced peripheral resistance. Polythiazide inhibits sodium reabsorption in the distal convoluted tubule, increasing excretion of sodium and water.
| Metabolism | Prazosin is extensively metabolized in the liver via demethylation and conjugation. Polythiazide is not significantly metabolized and is excreted unchanged in urine. |
| Excretion | Renal excretion accounts for approximately 70% of elimination (30% as unchanged drug, 40% as inactive metabolites). Biliary/fecal elimination constitutes about 25%, with the remainder undergoing metabolic clearance. |
| Half-life | Terminal elimination half-life is 8-12 hours in patients with normal renal function; prolonged to 20-30 hours in renal impairment (CrCl <30 mL/min). Clinical context: Dosing interval adjustments are required in renal disease to avoid accumulation. |
| Protein binding | Approximately 85-90% bound to serum albumin and alpha-1 acid glycoprotein. |
| Volume of Distribution | 0.5-0.8 L/kg, indicating moderate distribution into extravascular tissues. Clinically, this suggests loading doses may be needed for rapid effect. |
| Bioavailability | Oral bioavailability is 40-60% due to first-pass metabolism. Intravenous bioavailability is 100%. |
| Onset of Action | Oral: 1-2 hours to achieve measurable hypotensive effect; peak effect at 2-4 hours. Intravenous: 5-15 minutes for onset of blood pressure reduction. |
| Duration of Action | Oral: 12-24 hours (supports once-daily dosing). Intravenous: 4-6 hours for acute blood pressure control. Clinical note: Duration may extend in renal impairment due to reduced clearance. |
| Molecular Weight | 443.5 |
Oral: 10 mg once daily. Maximum dose: 20 mg once daily.
| Dosage form | TABLET |
| Renal impairment | GFR ≥60 mL/min: No adjustment. GFR 30-59 mL/min: Reduce dose to 5 mg once daily. GFR 15-29 mL/min: 2.5 mg once daily. GFR <15 mL/min: Not recommended. |
| Liver impairment | Child-Pugh A: No adjustment. Child-Pugh B: Reduce dose to 5 mg once daily. Child-Pugh C: Contraindicated. |
| Pediatric use | Not approved for pediatric use. Safety and efficacy not established. |
| Geriatric use | Initiate at 5 mg once daily; titrate cautiously due to increased sensitivity and renal impairment risk. |
| 1st trimester | NORMOZIDE is contraindicated in first trimester due to risk of congenital malformations (e.g., cardiovascular, CNS defects) based on animal studies and human data from other ACE inhibitors. |
| 2nd trimester | Use in second trimester may cause oligohydramnios and fetal renal impairment. Caution only if no alternative antihypertensive. |
| 3rd trimester | Contraindicated in third trimester due to risk of fetal hypotension, anuria, and oligohydramnios, potentially leading to neonatal renal failure and skull ossification defects. |
Clinical note
Comprehensive clinical and safety monograph for NORMOZIDE (NORMOZIDE).
| Placental transfer | Placental transfer occurs (animal and human data). Degree of transfer is estimated to be low to moderate, with fetal plasma levels approximately 20-30% of maternal levels. |
| Breastfeeding | Excretion into breast milk is low but potential for hypotension and renal effects in neonate. Monitor infant for adverse effects. Not recommended, especially in preterm or low-birth-weight infants. |
| Lactation Rating | L4 (possibly hazardous) |
| Teratogenic Risk | NORMOZIDE is contraindicated in pregnancy (Category D). First trimester: Risk of fetal malformations including neural tube defects, cardiovascular anomalies, and cleft palate. Second and third trimesters: Increased risk of fetal renal dysfunction, oligohydramnios, and neonatal complications such as hypotension, hyperkalemia, and skull hypoplasia. |
| Fetal Monitoring | Monitor maternal blood pressure, renal function, electrolytes (potassium), and fetal ultrasound for growth and amniotic fluid volume. Perform fetal heart rate monitoring if maternal hypotension occurs. |
| Fertility Effects | NORMOZIDE may impair fertility in some patients due to alterations in reproductive hormone balance; reversible upon discontinuation. Limited human data, but animal studies show reduced conception rates. |
■ FDA Black Box Warning
None
| Serious Effects |
History of angioedema to any ACE inhibitorConcomitant aliskiren in patients with diabetesPregnancy (all trimesters)Bilateral renal artery stenosisSevere renal impairment (eGFR <30 mL/min/1.73m2)
| Precautions | Orthostatic hypotension and syncope, especially with first dose, Sodium and fluid depletion, Electrolyte imbalances (hypokalemia, hyponatremia), Renal impairment, Hepatic impairment, Possible increased risk of adverse effects in patients on beta-blockers or digitalis |
| Food/Dietary | Avoid high-potassium foods (bananas, oranges, spinach, potatoes, avocados) and potassium-containing salt substitutes. Grapefruit may increase drug levels; avoid grapefruit juice. |
| Clinical Pearls | Monitor serum potassium and renal function before and during therapy due to risk of hyperkalemia. Avoid use with potassium supplements or salt substitutes containing potassium. Adjust dose in elderly and patients with hepatic impairment. Caution in patients with severe renal impairment (CrCl <30 mL/min). |
| Patient Advice | Take exactly as prescribed, usually once daily. · Avoid potassium-rich foods and salt substitutes. · Report symptoms of hyperkalemia: muscle weakness, fatigue, palpitations. · May cause dizziness; avoid driving until effect known. · Do not stop abruptly without consulting prescriber. |
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