NORMOZIDE

Clinical safety rating: caution

Comprehensive clinical and safety monograph for NORMOZIDE (NORMOZIDE).

How it works

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.

What the body does with it

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.

Classification & Brands

Dosing & administration

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.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for NORMOZIDE (NORMOZIDE).

Breastfeeding	NORMOZIDE is excreted in breast milk. M/P ratio: approximately 0.8. Avoid breastfeeding due to potential risk of hypotension and electrolyte disturbances in the infant.
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.

Warnings & precautions

■ FDA Black Box Warning

None

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to prazosin, polythiazide, or sulfonamides","Anuria","Hepatic coma or precoma","Concurrent use with phosphodiesterase-5 inhibitors (e.g., sildenafil)"]

Clinical Precautions

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"]

Clinical Tips & Counseling

Drug interactions

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NORMOZIDE

Clinical safety rating: caution

Comprehensive clinical and safety monograph for NORMOZIDE (NORMOZIDE).

How it works

What the body does with it

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.

Classification & Brands

Dosing & administration

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.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for NORMOZIDE (NORMOZIDE).

Breastfeeding	NORMOZIDE is excreted in breast milk. M/P ratio: approximately 0.8. Avoid breastfeeding due to potential risk of hypotension and electrolyte disturbances in the infant.
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.

Warnings & precautions

■ FDA Black Box Warning

None

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to prazosin, polythiazide, or sulfonamides","Anuria","Hepatic coma or precoma","Concurrent use with phosphodiesterase-5 inhibitors (e.g., sildenafil)"]