EFAVIRENZ 200MG SCORED TABLETS

Clinical safety rating: avoid

Induces CYP3A4 and inhibits CYP2C9/CYP2C19 affecting many drugs Can cause severe psychiatric symptoms and rash.

How it works

Non-nucleoside reverse transcriptase inhibitor (NNRTI); binds to reverse transcriptase, causing conformational change and inhibiting RNA-dependent and DNA-dependent DNA polymerase activity.

What the body does with it

Metabolism	Primarily metabolized by CYP2B6 and to a lesser extent CYP3A4, CYP2A6, and CYP1A2.
Excretion	Primarily hepatic metabolism via CYP2B6 and CYP3A4/5; <1% excreted unchanged in urine; ~14-34% of dose recovered in feces as metabolites; <1% in bile.
Half-life	Terminal half-life: 40-55 hours after single dose; 52-76 hours after multiple doses due to autoinduction; clinical context: allows once-daily dosing, but steady-state reached in 2-3 weeks; extended half-life in CYP2B6 poor metabolizers.
Protein binding	99.5-99.75% bound, primarily to albumin (98-99%) and also to alpha-1-acid glycoprotein.
Volume of Distribution	252-420 L (3.6-6.0 L/kg), indicating extensive tissue distribution; crosses blood-brain barrier with CSF concentrations 0.26-1.19% of plasma; high Vd contributes to long half-life.
Bioavailability	Oral bioavailability: 40-48% under fed conditions (high-fat meal increases absorption); take on empty stomach to reduce side effects; absolute bioavailability not determined due to lack of IV formulation.
Onset of Action	Oral: Plasma concentrations above therapeutic threshold (1 mg/L) achieved within 2-4 hours; antiviral effect begins within 24-48 hours of first dose.
Duration of Action	Approximately 24 hours with once-daily dosing; due to long half-life, missed doses up to 1-2 days may not significantly reduce efficacy, but consistent adherence is critical.

Classification & Brands

Dosing & administration

600 mg orally once daily, on an empty stomach, preferably at bedtime.

Dosage form	TABLET
Renal impairment	No dose adjustment required for renal impairment, including hemodialysis.
Liver impairment	Child-Pugh Class A: 600 mg daily. Child-Pugh Class B: 400 mg daily. Child-Pugh Class C: contraindicated.
Pediatric use	Body weight 10-<15 kg: 200 mg once daily; 15-<20 kg: 250 mg; 20-<25 kg: 300 mg; 25-<32.5 kg: 350 mg; 32.5-<40 kg: 400 mg; ≥40 kg: 600 mg.
Geriatric use	No specific dose adjustment, but monitor for CNS effects and hepatic function due to increased sensitivity.

Use during pregnancy

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

Clinical note

Induces CYP3A4 and inhibits CYP2C9/CYP2C19 affecting many drugs Can cause severe psychiatric symptoms and rash.

FDA category	Contraindicated
Breastfeeding	Excreted into human breast milk; M/P ratio approximately 0.5-0.9. Insufficient data on infant effects; avoid breastfeeding due to potential for viral resistance and adverse effects in infants.
Teratogenic Risk	FDA Pregnancy Category D. First trimester exposure associated with neural tube defects (e.g., myelomeningocele, anencephaly) at an incidence of 0.5-1.0%. Second and third trimester risks include decreased fetal growth and preterm delivery. Contraindicated in pregnancy unless no alternative.

Warnings & precautions

■ FDA Black Box Warning

Not recommended for use in patients with moderate to severe hepatic impairment (Child-Pugh class B or C).

Side Effect Profile

Common Effects	Rash
Serious Effects

Absolute Contraindications

["Concomitant use with voriconazole","Concomitant use with ribavirin/peginterferon alfa in HCV/HIV co-infected patients with decompensated liver disease"]

Clinical Precautions

Precautions

["Hepatotoxicity","Psychiatric symptoms (severe depression, suicidal ideation)","Nervous system symptoms (dizziness, insomnia, somnolence)","Seizures","Rash (including Stevens-Johnson syndrome)","Lipid elevation","Redistribution/accumulation of body fat","Embryo-fetal toxicity","Contraindicated with CYP3A4 inducers/inhibitors that may reduce efavirenz exposure"]

Clinical Tips & Counseling

Drug interactions

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EFAVIRENZ 200MG SCORED TABLETS

Clinical safety rating: avoid

Induces CYP3A4 and inhibits CYP2C9/CYP2C19 affecting many drugs Can cause severe psychiatric symptoms and rash.

How it works

Non-nucleoside reverse transcriptase inhibitor (NNRTI); binds to reverse transcriptase, causing conformational change and inhibiting RNA-dependent and DNA-dependent DNA polymerase activity.

What the body does with it

Metabolism	Primarily metabolized by CYP2B6 and to a lesser extent CYP3A4, CYP2A6, and CYP1A2.
Excretion	Primarily hepatic metabolism via CYP2B6 and CYP3A4/5; <1% excreted unchanged in urine; ~14-34% of dose recovered in feces as metabolites; <1% in bile.
Half-life	Terminal half-life: 40-55 hours after single dose; 52-76 hours after multiple doses due to autoinduction; clinical context: allows once-daily dosing, but steady-state reached in 2-3 weeks; extended half-life in CYP2B6 poor metabolizers.
Protein binding	99.5-99.75% bound, primarily to albumin (98-99%) and also to alpha-1-acid glycoprotein.
Volume of Distribution	252-420 L (3.6-6.0 L/kg), indicating extensive tissue distribution; crosses blood-brain barrier with CSF concentrations 0.26-1.19% of plasma; high Vd contributes to long half-life.
Bioavailability	Oral bioavailability: 40-48% under fed conditions (high-fat meal increases absorption); take on empty stomach to reduce side effects; absolute bioavailability not determined due to lack of IV formulation.
Onset of Action	Oral: Plasma concentrations above therapeutic threshold (1 mg/L) achieved within 2-4 hours; antiviral effect begins within 24-48 hours of first dose.
Duration of Action	Approximately 24 hours with once-daily dosing; due to long half-life, missed doses up to 1-2 days may not significantly reduce efficacy, but consistent adherence is critical.

Classification & Brands

Dosing & administration

600 mg orally once daily, on an empty stomach, preferably at bedtime.

Dosage form	TABLET
Renal impairment	No dose adjustment required for renal impairment, including hemodialysis.
Liver impairment	Child-Pugh Class A: 600 mg daily. Child-Pugh Class B: 400 mg daily. Child-Pugh Class C: contraindicated.
Pediatric use	Body weight 10-<15 kg: 200 mg once daily; 15-<20 kg: 250 mg; 20-<25 kg: 300 mg; 25-<32.5 kg: 350 mg; 32.5-<40 kg: 400 mg; ≥40 kg: 600 mg.
Geriatric use	No specific dose adjustment, but monitor for CNS effects and hepatic function due to increased sensitivity.

Use during pregnancy

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

Clinical note

Induces CYP3A4 and inhibits CYP2C9/CYP2C19 affecting many drugs Can cause severe psychiatric symptoms and rash.

FDA category	Contraindicated
Breastfeeding	Excreted into human breast milk; M/P ratio approximately 0.5-0.9. Insufficient data on infant effects; avoid breastfeeding due to potential for viral resistance and adverse effects in infants.
Teratogenic Risk	FDA Pregnancy Category D. First trimester exposure associated with neural tube defects (e.g., myelomeningocele, anencephaly) at an incidence of 0.5-1.0%. Second and third trimester risks include decreased fetal growth and preterm delivery. Contraindicated in pregnancy unless no alternative.

Warnings & precautions

■ FDA Black Box Warning

Not recommended for use in patients with moderate to severe hepatic impairment (Child-Pugh class B or C).

Side Effect Profile

Common Effects	Rash
Serious Effects

Absolute Contraindications

["Concomitant use with voriconazole","Concomitant use with ribavirin/peginterferon alfa in HCV/HIV co-infected patients with decompensated liver disease"]