Efavir 200mg (Efavirenz)

Efavir general information

What is Efavir used for?

Efavir capsules 200mg (also known as Sustiva) are used with other HIV medications as part of combination therapy for the treatment of Human Immunodeficiency Virus (HIV) infection in adults and children three years of age or older.  Efavir 200 must not be used alone as the virus can develop resistance if used as monotherapy and Efavir 200 is, therefore, combined with two other drugs that have a different mechanism of action.  This treatment regime is known as highly active antiretroviral therapy (HAART) and is designed to minimise the ability of the virus to multiply and help prevent development of viral resistance to treatment.  HIV impairs the immune system by attacking specific immune cells called CD4⁺ cells that are involved in fighting infection and this can lead to opportunistic life-threatening infection (infections that would not normally be harmful).  Also if too many CD4⁺ cells are destroyed this can result in acquired immune deficiency syndrome (AIDS).  Efavir 200 slows down the ability of HIV to replicate and spread, which keeps the amount virus down to a low level (reduces viral load) and this results in an increase in CD4⁺ cell numbers, so that the immune system can recover, reducing the risk of disease progression. 

How does Efavir work?

Efavir capsule 200mg (also known as Sustiva) contain efavirenz, a non-nucleoside analogue reverse transcriptase inhibitor (NNRTI), which is only effective against RNA viruses (retroviruses) like Human Immunodeficiency Virus (HIV).  It works by inhibiting the action of the viral-specific enzyme reverse transcriptase (RT), which is needed for the virus to be able to replicate.  Retroviruses convert RNA to DNA, which is then integrated into the DNA of infected immune cells so that the virus can replicate.  Efavirenz in Efavir 200 acts by binding to a specific site on the RT enzyme and blocks its action in a manner that is noncompetitive with nucleosides (precursors to the building blocks of DNA and RNA), thereby preventing the conversion of viral RNA to DNA.  This action prevents the integration of virus into the DNA of the infected CD4⁺ immune cell, which inhibits the replication of HIV so that no more virus can be produced; and this reduces the viral load (amount of virus).  Efavir capsule 200mg slow down the replication of HIV within your body but does not kill the virus already incorporated in the CD4⁺ cells or prevent the spread of the infection to others. 

What does Efavir contain?

Efavir capsules 200mg contains the active ingredient efavirenz, a non-nucleoside analogue reverse transcriptase inhibitors (NNRTI) that is used as part of a combination treatment for Human Immunodeficiency Virus (HIV) infection.  The active ingredient is contained in a hard gelatin capsule.

Treating HIV infection with Efavir

Efavir capsules 200mg (also known as Sustiva) contain efavirenz, an antiretroviral drug that is effective only against RNA viruses (retroviruses) like Human Immunodeficiency Virus (HIV).  Efavirenz in Efavir 200 works by inhibiting the action of the viral-specific enzyme reverse transcriptase (RT), which is needed for the virus to be able to replicate.  HIV impairs the immune system by attacking specific immune cells called CD4⁺ cells that are involved in fighting infection, and this can lead to opportunistic life-threatening infection (infections that would not normally be harmful), including pneumonia, herpes virus infections, and Mycobacterium avium complex (MAC) infection.  If too many CD4⁺ cells are destroyed this can result in acquired immune deficiency syndrome (AIDS).  Efavirenz in Efavir 200 is a non-nucleoside analogue reverse transcriptase inhibitors (NNRTI) and blocks the action of RT in a manner that is noncompetitive with nucleosides (precursors to the building blocks of DNA and RNA), thereby preventing the conversion of viral RNA to DNA.  This action prevents the integration of virus into the DNA of the infected CD4⁺ immune cell, which inhibits the replication of HIV so that no more virus can be produced; and this reduces the viral load (amount of virus).  Efavir 200 slows down the replication of HIV within your body but does not kill the virus already incorporated in the CD4⁺ cells or prevent the spread of the infection to others. 

What are the side effects of Efavir?

The most commonly reported side effects when taking Efavir 200 include: abdominal pain, diarrhoea, nausea, vomiting, skin rash and itching,, dizziness, headache, fatigue, insomnia, drowsiness, inability to concentrate, abnormal dreaming.

When should Efavir not be used?

You should not use Efavir capsules 200mg if you:

• are allergic to efavirenz or any ingredients in Efavir
• are pregnant or are breastfeeding
• have liver disease
• are using Efavir 200 as a single treatment as it is intended for use only as part of combination therapy
• are taking medicines that interact with Efavir 200 including: other antiretrovirals, such as, amprenavir, indinavir, atazanavir, ritonavir, saquinavir, the antibiotics rifampicin, rifabutin and clarithromycin, the antifungals voriconazole and itraconazole, cholesterol lowering statins like simvastatin and atorvastatin, the antiepileptic carbamazepine, oestrogen containing oral contraceptives, methadone for opioid dependence, the dietary supplement St. John's Wort, the antidepressant sertraline, calcium channel blockers like diltiazem for angina and hypertension, the antihistamine terfenadine, cisapride for reflux, triazolam for anxiety, the sedative midazolam, ergot derivatives for migraine, the antipsychotic pimozide, bepridil for angina

What medications interact with Efavir?

Several medications interact with Efavir capsules 200mg and should either not be taken while you are taking Efavir or only after discussion and instruction from your doctor:

• Drugs that cause a serious reaction with Efavir:, the antihistamine terfenadine, cisapride for reflux, triazolam for anxiety, the sedative midazolam, ergot derivatives for migraine, bepridil for angina
• Drugs that affect Efavir: other antiretrovirals, such as, ritonavir, amprenavir, atazanavir, indinavir, saquinavir the antibiotic rifampicin, the antiepileptic carbamazepine, the dietary supplement St. John's Wort,
• Drugs that are affected by Efavir: the antibiotics rifabutin and clarithromycin, the antifungals voriconazole and itraconazole, cholesterol lowering statins like simvastatin and atorvastatin, the antiepileptic carbamazepine, oestrogen containing oral contraceptives, methadone for opioid dependence

How should Efavir be taken?

You should take your Efavir capsules 200mg swallowed whole with a glass of water without food, once a day preferably on an empty stomach at bedtime to reduce problems with side effects.  The dose you take depends on your body weight and your doctor’s recommendation.  You should continue to take your Efavir 200 regularly for as long as your doctor recommends, and you condition should be monitored.  Do not suddenly stop taking your Efavir 200 as this may increase risk of HIV resistance.

How long should you take Efavir?

You should continue to take your Efavir capsules 200mg regularly for as long as your doctor recommends, and you condition should be monitored.  Do not suddenly stop taking your Efavir 200 as this may increase risk of HIV resistance.

Missed dose of Efavir

If you miss a dose of Efavir capsules 200mg take it as soon as you remember, unless it is time to take the next dose, then skip the missed dose.  Do not take a double dose.

How should Efavir be stored?

You should store your Efavir below 25°C in a cool dry place.