ENDURONYL

Clinical safety rating: caution

Comprehensive clinical and safety monograph for ENDURONYL (ENDURONYL).

How it works

Thiazide diuretic that inhibits the Na+-Cl− symporter in the distal convoluted tubule, reducing sodium and chloride reabsorption and promoting diuresis.

What the body does with it

Metabolism	Not extensively metabolized; primarily excreted unchanged in urine.
Excretion	Primarily renal excretion; ~50% unchanged, ~25% as deserpidine metabolites, 20% biliary-fecal.
Half-life	Terminal elimination half-life 10-15 hours; clinically, may require 3-5 days to reach steady state in hypertension management.
Protein binding	~90% bound to plasma proteins, primarily albumin and alpha-1 acid glycoprotein.
Volume of Distribution	2-4 L/kg; indicates extensive distribution into tissues, particularly adipose and brain.
Bioavailability	Oral: ~50% due to first-pass metabolism; parenteral not available.
Onset of Action	Oral: 2-4 hours for initial antihypertensive effect; parenteral not applicable.
Duration of Action	Oral: 12-24 hours; clinical effect persists for 24-48 hours after discontinuation due to tissue binding.

Classification & Brands

Dosing & administration

ENDURONYL (methyclothiazide and deserpidine) is a fixed-dose combination antihypertensive. Typical adult dose: 1 tablet (methyclothiazide 5 mg / deserpidine 0.25 mg) orally once daily. Dose may be increased to 2 tablets once daily if needed.

Dosage form	TABLET
Renal impairment	Contraindicated in anuria. For GFR 30-59 mL/min: use with caution, reduce dose or increase interval; monitor electrolytes. GFR <30 mL/min: not recommended. Avoid use in severe renal impairment.
Liver impairment	Child-Pugh A: no adjustment necessary. Child-Pugh B: use with caution; deserpidine may precipitate hepatic encephalopathy. Child-Pugh C: contraindicated due to risk of electrolyte imbalance and encephalopathy.
Pediatric use	Safety and efficacy not established in pediatric patients; use not recommended.
Geriatric use	Initiate at lowest dose: 0.5 tablet (methyclothiazide 2.5 mg / deserpidine 0.125 mg) orally once daily. Titrate slowly due to increased risk of electrolyte disturbances, hypotension, and central nervous system effects. Monitor renal function and electrolytes closely.

Use during pregnancy

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

Clinical note

Comprehensive clinical and safety monograph for ENDURONYL (ENDURONYL).

Breastfeeding	Methyclothiazide is excreted in human milk in small amounts. M/P ratio not established. Thiazides may suppress lactation. Breastfeeding is generally not recommended due to potential for adverse effects in the infant, such as electrolyte imbalance. Alternative diuretics preferred.
Teratogenic Risk	ENDURONYL (methyclothiazide) is a thiazide diuretic. First trimester: Limited human data; theoretical risk of teratogenicity based on animal studies showing fetal abnormalities at high doses. Second and third trimesters: May cause fetal or neonatal jaundice, thrombocytopenia, electrolyte disturbances, and possibly other adverse effects. Use only if clearly needed.

Warnings & precautions

■ FDA Black Box Warning

No FDA black box warning.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Anuria","Renal failure","Hepatic coma or precoma","Hypersensitivity to thiazides or sulfonamide-derived drugs","Severe electrolyte depletion"]

Clinical Precautions

Precautions

["Hypokalemia","Hyponatremia","Hypomagnesemia","Hyperuricemia","Hyperglycemia","Hypercalcemia","Orthostatic hypotension","Photosensitivity","Systemic lupus erythematosus exacerbation","Acute angle-closure glaucoma"]

Clinical Tips & Counseling

Drug interactions

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ENDURONYL

Clinical safety rating: caution

Comprehensive clinical and safety monograph for ENDURONYL (ENDURONYL).

How it works

Thiazide diuretic that inhibits the Na+-Cl− symporter in the distal convoluted tubule, reducing sodium and chloride reabsorption and promoting diuresis.

What the body does with it

Metabolism	Not extensively metabolized; primarily excreted unchanged in urine.
Excretion	Primarily renal excretion; ~50% unchanged, ~25% as deserpidine metabolites, 20% biliary-fecal.
Half-life	Terminal elimination half-life 10-15 hours; clinically, may require 3-5 days to reach steady state in hypertension management.
Protein binding	~90% bound to plasma proteins, primarily albumin and alpha-1 acid glycoprotein.
Volume of Distribution	2-4 L/kg; indicates extensive distribution into tissues, particularly adipose and brain.
Bioavailability	Oral: ~50% due to first-pass metabolism; parenteral not available.
Onset of Action	Oral: 2-4 hours for initial antihypertensive effect; parenteral not applicable.
Duration of Action	Oral: 12-24 hours; clinical effect persists for 24-48 hours after discontinuation due to tissue binding.

Classification & Brands

Dosing & administration

Dosage form	TABLET
Renal impairment	Contraindicated in anuria. For GFR 30-59 mL/min: use with caution, reduce dose or increase interval; monitor electrolytes. GFR <30 mL/min: not recommended. Avoid use in severe renal impairment.
Liver impairment	Child-Pugh A: no adjustment necessary. Child-Pugh B: use with caution; deserpidine may precipitate hepatic encephalopathy. Child-Pugh C: contraindicated due to risk of electrolyte imbalance and encephalopathy.
Pediatric use	Safety and efficacy not established in pediatric patients; use not recommended.
Geriatric use	Initiate at lowest dose: 0.5 tablet (methyclothiazide 2.5 mg / deserpidine 0.125 mg) orally once daily. Titrate slowly due to increased risk of electrolyte disturbances, hypotension, and central nervous system effects. Monitor renal function and electrolytes closely.

Use during pregnancy

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

Clinical note

Comprehensive clinical and safety monograph for ENDURONYL (ENDURONYL).

Breastfeeding	Methyclothiazide is excreted in human milk in small amounts. M/P ratio not established. Thiazides may suppress lactation. Breastfeeding is generally not recommended due to potential for adverse effects in the infant, such as electrolyte imbalance. Alternative diuretics preferred.
Teratogenic Risk	ENDURONYL (methyclothiazide) is a thiazide diuretic. First trimester: Limited human data; theoretical risk of teratogenicity based on animal studies showing fetal abnormalities at high doses. Second and third trimesters: May cause fetal or neonatal jaundice, thrombocytopenia, electrolyte disturbances, and possibly other adverse effects. Use only if clearly needed.

Warnings & precautions

■ FDA Black Box Warning

No FDA black box warning.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Anuria","Renal failure","Hepatic coma or precoma","Hypersensitivity to thiazides or sulfonamide-derived drugs","Severe electrolyte depletion"]