Drug profile of Efavir
Efavir is an anti-retroviral drug which consisting of an active moiety known as efavirenz exhibiting its activity against HIV-1 infections.
Efavir tablets are non nucleoside reverse transcriptase prohibitor.
Efavir is not a curable medicine; it slows down the progression of infection into AIDS.
Efavir is used in combination with other anti-retroviral medication for better activity.
Brand name: Efavir
Active ingredient: Efavirenz
Pack: 30 tablets in a container
Category: Anti-retroviral drug
Prescribing information of Efavir
Efavir tablets are anti-retroviral drug which is used in HIV infection, by combining with other anti-retroviral drugs.
Mechanism of Efavir
The mechanism of action of efavirenz is similar to lamivudine.
Efavirenz is exhibits activity by inhibiting the activity of viral RNA directed DNA polymerase enzyme which is a reverse transcriptase.
The intracellular alteration to active triphosphorylated form which is essential for the activity of efavirenz.
Depending up on the cell type, the phosphorylation occurs.
The production of DNA copies of viral RNA is interceded by inhibition of reverse transcriptase.
This generation is necessary for production of new viral assembly.
Finally the inhibition causes cell division termination.
The maximum plasma concentration of efavirenz is attained at 5 hours.
The time to maximum plasma concentration time is relatively 3 to 5 hours.
The steady state of efavirenz is reached within 6 to 10 days.
Efavirenz is highly bound to human plasma protein nearly 99.5 to 99.7%.
The metabolism of efavirenz is majorly occurred by cytochrome P450 enzymes to hydrolyzed metabolites.
The major isoenzymes are CYP3A & CYP2B6.
The terminal mean half life period of efavirenz is 52 to 76 hours.
14 to 34% of radiolabel should be eliminated through urine and 16-61% eliminated via feces.
When to take the Efavir
Efavirenz should be administered on an empty stomach during at bed time.
Dosage regimens of Efavir
The usual advice prescribed dose of Efavir in adults is 600mg of tablet should be administered orally as a single dose by combining with protease inhibitors or nucleoside analogue reverse transcriptase inhibitors.
The concentration of efavirenz should be elevated when the Efavir tablet should be administered with food which leads to increase the adverse effects associated to Efavir.
The up take drug at bed time should elevate the tolerability of nervous system symptoms.
Combination of Efavir with voriconazole, the continuance dose of voriconazole should be elevated to 400mg for every 12 hours and the Efavir dose should be depletes to 300mg as a single dose.
Efavir tablets should not be broke, chew or crush.
In combination with rifampin, the dose of Efavir is 800mg
The dose of Efavir should be suggested for the pediatric patients with the age of 3 years.
10 to < 15kg: 200mg of efavirenz should be recommended
15 to <20kg: 250mg of efavirenz should be recommended
20 to <25kg: 300mg of efavirenz should be recommended
25 to <32.5kg: 350mg of efavirenz should be recommended
32.5 To <40kg: 400mg of efavirenz should be recommended
At least 40kg: 600mg of efavirenz should be recommended
Efavir caused side effects
Nervous system symptoms
The common side effects of efavirenz are;
Elevation of AST, ALT
Increased glucose level
An increased hepatic enzyme leads to hepatic failure
Abnormal in vision
Drug- drug interaction
Efavirenz combined with compounds that are substrates of CYP3A or CYP2B6 may leads to deplete the plasma concentration.
Co administration of efavirenz with the drugs which are metabolized by CYP2C9, 2C19, & 3A4 may vary the plasma concentration of efavirenz.
Efavirenz combined with CYP3A inducers, this combination results as elevates the clearance of efavirenz and leads to deplete the plasma concentration.
Efavir tablet combined with protease inhibitors except ritonavir, causes increasing the effect of concentration of PI’s.
Efavir with NNRTI leads to cause decreasing or increasing the effect of concentration of NNRTI.
Efavir with anti-convulsants, anti-depressants or anti-fungal, are leads to cause decreasing the effect of concentration of these drugs.
Efavir is combined with either anti-infective or anti-mycobacterials may cause decreased effect of concentration of these drugs.
The Co administration of Efavir with calcium channel blocker, or lipid lowering drugs causes decreasing the effect of concentration of these drugs.
Efavir combined with hormonal contraceptives or Immuno suppressants causes decreasing the effect of concentration of these drugs.
Food drug interaction
When the Efavir tablets administered with food, causes elevates the amount of Efavir content in the body. This may concluded as increasing in adverse effect associated with efavirenz.
Efavir should be taken on an empty stomach, at bed time for reducing the side effects like dizziness, trouble sleeping, drowsiness, neurological disorders.
Efavir receiving patients should not consume alcohol, it may cause severe effects.
High fat containing foods should not be used during the therapy, because efavirenz causes increasing the cholesterol levels.
Hypersensitivity reactions are produced due to patients may contraindicate to the components present in the Efavir tablets.
Contraindicated drugs like;
Due to this effect, patients may affect with severe life threatening conditions. Avoid the combinational therapy. Some of the drugs are given below;
Anti-migraine like ergot derivatives
Calcium channel blockers
GI motility agents
St John’s wort
Some adverse effects are produced due to drug interactions, like Efavir with CYP3A inducers or inhibitors causes alteration in pharmacokinetic property leads to vary in therapeutic effects.
Resistance: Efavir tablets are not used as a single agent, it should be combined with other anti-retroviral agents. The emergence of resistance virus is produced while using Efavir as monotherapy.
The co administration of Efavir with Atripla should not be recommended.
Psychiatric symptoms are most common adverse effects occur during the therapy with Efavirenz.
If the adverse effects continued, then discontinue the treatment.
Provide safety measures.
Efavir used by combining with alcohol, or any psychiatric drugs may causes some neurological problems.
Avoid the combination and provide with supportive therapy for reducing the adverse.
Efavir is contraindicated to pregnant & lactating women
Rashes are occurred during the treatment, treated with anti-histamines therapy for the patients who are acquired rashes during the efavirenz therapy.
Liver toxicity, may occurs due to elevation of hepatic enzymes
Convulsions are also occurred during the Efavir treatment, known as seizures./
Patient’s medical history should be considered before starting the therapy.
Provide anti-convulsants which are formerly metabolized by liver like phenytoin, Phenobarbital etc.
Periodic monitoring of plasma levels should be occurring to determine the level of anti-convulsants present in plasma.
The main adverse effect of Efavir tablets is elevation of lipid levels.
To overcome the problems patient should be monitor frequently by analyzing cholesterol levels.
Immune reconstitution syndrome is most probably occurred during efavirenz treatment. In this condition, Efavir tablets should be stopped.
The reaccumulation of fat content occurs in the patients who are receiving Efavir treatment.
The major adverse effect caused due to this effect is obesity.
Pregnancy and lactation
Pregnancy category: D
Efavir tablets are not used in pregnancy condition, may causes embryo fetal damage
Breast feeding is also not suggested.
Storage and handling
The Efavir tablet container should be stored at temperature of 25oC (77oF); with excursion between 15oC to 30oC.
Keep the container away from moisture, heat & light.
In case of missed dose, patient must be get advice from medical practitioner for avoiding the over dosage effect.
Follow with regular dosing schedule.
The Efavir tablets should be taken as two times a day with the dose of 600mg may have chance of causing neurological symptoms.
The manifestation related to over dosage of efavirenz should be monitored periodically.
Patients should be provided with some supportive measures.
Using activated charcoal leads to eliminate the unabsorbed drug present in the body.
Efavirenz has high protein bound capacity, dialysis is not used to remove the over dose of efavirenz.