Efavirenz is a non-nucleotide reverse transcriptase inhibitor.

MOA
Efavirenz noncompetitively binds to a site other than catalytic site in the HIV- 1 reverse transcriptase enzyme .This binding will results in a structural change in the enzyme and inhibits its activity i.e. conversion of viral RNA to pro viral DNA and subsequent virus replication

Pharmaco Kinetic
Absorption: It is absorbed after oral administration. Distribution: It is widely distributed in the body in protein bound form. Metabolism: It is metabolised in the liver to inactive metabolite. Excretion: The drug is primarily excreted through faeces and it is also excreted through urine.

Adverse Effect
1.Rash
2.Stevens-Johnson syndrome
3.Dizziness
4.Headache
5.Insomnia
6.Hallucination
7.Diarrhoea
8.Anorexia
9.Impaired concentration
10.Dysphoria

ContraIndications
Hypersensitivity to Efavirenz

Special Precautions
1.Renal impairment
2.Hepatic impairment
3.Psychiatric patients
4.Patient with increased cholesterol level and serum transaminases level

Pregnancy
Contraindicated  

Breast Feeding
Contraindicated.

Elderly
Use with caution.

Children
Use with caution.

Neonates:
Contraindicated

Interactions
Grapefruit juice may affect plasma efavirenz concentration.
Antibacterials: Increased risk of rash with clarithromycin. Rifampicin reduces plasma concentration of efavirenz.
Antidepressants: Avoid concomitant use of St. John’s Wort (Hypericum perforatum - a long living plant with yellow flowers).
Antihistaminics: Increased risk of ventricular arrhythmias when used with terfenadine.
Other antivirals: Efavirenz reduces plasma concentration of amprenavir, indinavir and lipinavir. Efavirenz reduces plasma concentration of saquinavir.
Anxiolytics: Risk of prolonged sedation with Midazolam.
Oestrogen and Progestogens: Possibly reduced efficacy of oral contraceptives.

Indications
HIV-1 infection

Dosage
Adults: 600mg once daily along with other antiretroviral agent.
Children:
Over 3 years(13-14kg body weight) : 200mg once daily;
15-19kg body weight: 250mg once daily;
20-24kg body weight: 300mg once daily;
25-32.4kg body weight: 350mg once daily;
32.5-39kg body weight: 400mg once daily;
Above 40kg body weight: same as adult dose

Storage
Store at 15 - 30 degree C in a tightly closed container. Protect away from heat and light. Keep out of the reach of Children.

Missed Dose
Take the missed dose as soon as noticed and if it is the time to take the next dose then skip the missed dose.

Over Dose
Give supportive measures and treatment. Activated charcoal can be given to reduce the absorption of the drug.