INVERSINE

Clinical safety rating: caution

Comprehensive clinical and safety monograph for INVERSINE (INVERSINE).

How it works

Mecamylamine is a noncompetitive antagonist of nicotinic acetylcholine receptors, blocking ganglionic transmission in both sympathetic and parasympathetic ganglia.

What the body does with it

Metabolism	Primarily hepatic metabolism (unknown specific enzymes); eliminated renally with unchanged drug and metabolites.
Excretion	Primarily renal (about 90% as unchanged drug), with minor biliary/fecal elimination (<10%).
Half-life	3-5 hours in patients with normal renal function; may be prolonged in renal impairment (up to 12-24 hours in severe cases).
Protein binding	~50% bound to plasma proteins (mainly albumin).
Volume of Distribution	Approximately 1 L/kg, indicating extensive extravascular distribution.
Bioavailability	Oral: 50-75% (due to first-pass metabolism).
Onset of Action	Oral: 30-60 minutes; Intravenous: 5-15 minutes.
Duration of Action	Oral: 4-6 hours; IV: 2-4 hours. Effect may persist longer in patients with impaired renal function.

Classification & Brands

Dosing & administration

Initial: 2.5 mg orally twice daily; increase by 2.5-5 mg every 2-3 days until blood pressure controlled; usual maintenance: 10-75 mg/day in 2-4 divided doses; max single dose: 25 mg; max daily dose: 200 mg.

Dosage form	TABLET
Renal impairment	GFR 30-60 mL/min: reduce dose by 50%; GFR 10-29 mL/min: reduce dose by 75%; GFR <10 mL/min: avoid use.
Liver impairment	Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: avoid use.
Pediatric use	Not recommended for pediatric use due to lack of safety and efficacy data.
Geriatric use	Start at 2.5 mg once daily; increase slowly; monitor for orthostatic hypotension and syncope.

Use during pregnancy

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

Clinical note

Comprehensive clinical and safety monograph for INVERSINE (INVERSINE).

Breastfeeding	Excreted in breast milk. M/P ratio unknown. Discontinue breastfeeding due to potential for serious adverse effects in infant.
Teratogenic Risk	Category C. First trimester: No adequate human studies; animal studies show embryotoxicity. Second/third trimester: Potential for meconium ileus, neonatal hypotension. Avoid in pregnancy.
Fetal Monitoring	Monitor maternal blood pressure and heart rate; fetal growth and amniotic fluid index via ultrasound; neonatal monitoring for hypotension and respiratory depression after delivery.

Warnings & precautions

■ FDA Black Box Warning

None.

Side Effect Profile

Serious Effects

Absolute Contraindications

Coronary insufficiency, recent myocardial infarction, pyloric stenosis, glaucoma, uremia, and patients receiving concurrent antihypertensive therapy with ganglionic blocking agents.

Clinical Precautions

Precautions

May cause orthostatic hypotension, syncope, and falls. Use with caution in patients with cerebrovascular insufficiency, renal impairment, or recent myocardial infarction. Discontinue if symptoms of paralytic ileus occur.

Clinical Tips & Counseling

Drug interactions

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INVERSINE

Clinical safety rating: caution

Comprehensive clinical and safety monograph for INVERSINE (INVERSINE).

How it works

Mecamylamine is a noncompetitive antagonist of nicotinic acetylcholine receptors, blocking ganglionic transmission in both sympathetic and parasympathetic ganglia.

What the body does with it

Metabolism	Primarily hepatic metabolism (unknown specific enzymes); eliminated renally with unchanged drug and metabolites.
Excretion	Primarily renal (about 90% as unchanged drug), with minor biliary/fecal elimination (<10%).
Half-life	3-5 hours in patients with normal renal function; may be prolonged in renal impairment (up to 12-24 hours in severe cases).
Protein binding	~50% bound to plasma proteins (mainly albumin).
Volume of Distribution	Approximately 1 L/kg, indicating extensive extravascular distribution.
Bioavailability	Oral: 50-75% (due to first-pass metabolism).
Onset of Action	Oral: 30-60 minutes; Intravenous: 5-15 minutes.
Duration of Action	Oral: 4-6 hours; IV: 2-4 hours. Effect may persist longer in patients with impaired renal function.

Classification & Brands

Dosing & administration

Dosage form	TABLET
Renal impairment	GFR 30-60 mL/min: reduce dose by 50%; GFR 10-29 mL/min: reduce dose by 75%; GFR <10 mL/min: avoid use.
Liver impairment	Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: avoid use.
Pediatric use	Not recommended for pediatric use due to lack of safety and efficacy data.
Geriatric use	Start at 2.5 mg once daily; increase slowly; monitor for orthostatic hypotension and syncope.

Use during pregnancy

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

Clinical note

Comprehensive clinical and safety monograph for INVERSINE (INVERSINE).

Breastfeeding	Excreted in breast milk. M/P ratio unknown. Discontinue breastfeeding due to potential for serious adverse effects in infant.
Teratogenic Risk	Category C. First trimester: No adequate human studies; animal studies show embryotoxicity. Second/third trimester: Potential for meconium ileus, neonatal hypotension. Avoid in pregnancy.
Fetal Monitoring	Monitor maternal blood pressure and heart rate; fetal growth and amniotic fluid index via ultrasound; neonatal monitoring for hypotension and respiratory depression after delivery.

Warnings & precautions

■ FDA Black Box Warning

None.

Side Effect Profile

Serious Effects

Absolute Contraindications

Coronary insufficiency, recent myocardial infarction, pyloric stenosis, glaucoma, uremia, and patients receiving concurrent antihypertensive therapy with ganglionic blocking agents.