Zefdavir 100 Uses

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What is Zefdavir 100?

Zefdavir 100 is used in combination with other medicines for the treatment of the infection caused by the human immunodeficiency virus (HIV). HIV is the virus that causes acquired immune deficiency syndrome (AIDS).

Zefdavir 100 will not cure or prevent HIV infection or AIDS. It helps keep HIV from reproducing and appears to slow down the destruction of the immune system. This may help delay the development of serious health problems usually related to AIDS or HIV disease from occurring. Zefdavir 100 will not keep you from spreading HIV to other people. People who receive Zefdavir 100 may continue to have other problems usually related to AIDS or HIV disease.

Zefdavir 100 is also used to treat chronic (long-term) hepatitis B virus (HBV) infection.

Zefdavir 100 is available only with your doctor's prescription.

Once a medicine has been approved for marketing for a certain use, experience may show that it is also useful for other medical problems. Although this use is not included in product labeling, Zefdavir 100 is used in certain patients with the following medical condition:

  • Human immunodeficiency virus (HIV) infection due to occupational exposure (possible prevention of)

Zefdavir 100 indications

An indication is a term used for the list of condition or symptom or illness for which the medicine is prescribed or used by the patient. For example, acetaminophen or paracetamol is used for fever by the patient, or the doctor prescribes it for a headache or body pains. Now fever, headache and body pains are the indications of paracetamol. A patient should be aware of the indications of medications used for common conditions because they can be taken over the counter in the pharmacy meaning without prescription by the Physician.

Zefdavir 100 tablets are indicated for the treatment of chronic hepatitis B virus (HBV) infection associated with evidence of hepatitis B viral replication and active liver inflammation.

The following points should be considered when initiating therapy with Zefdavir 100 tablets:

Due to high rates of resistance development in treated patients, initiation of treatment with Zefdavir 100 tablets should only be considered when the use of an alternative antiviral agent with a higher genetic barrier to resistance is not available or appropriate.
Zefdavir 100 tablets have not been evaluated in patients co-infected with HIV, hepatitis C virus (HCV), or hepatitis delta virus.
Zefdavir 100 tablets have not been evaluated in liver transplant recipients or in patients with chronic hepatitis B virus infection with decompensated liver disease.
Zefdavir 100 tablets have not been evaluated in pediatric patients younger than 2 years of age with chronic HBV infection.

How should I use Zefdavir 100?

Use Zefdavir 100

Oral Solution as directed by your doctor. Check the label on the medicine for exact dosing instructions.

  • An extra patient leaflet is available with Zefdavir 100

    Oral Solution. Talk to your pharmacist if you have questions about this information.

  • Take Zefdavir 100

    Oral Solution by mouth with or without food.

  • Use a measuring device marked for medicine dosing. Ask your pharmacist for help if you are unsure of how to measure your dose.
  • Continue to take Zefdavir 100

    Oral Solution even if you feel well. Do not miss any doses.

  • Taking Zefdavir 100

    Oral Solution at the same time each day will help you remember to take it.

  • If you miss a dose of Zefdavir 100

    Oral Solution, take it as soon as possible. If it is within 2 hours of your next dose, skip the missed dose and go back to your regular dosing schedule. Do not take 2 doses at once.

Ask your health care provider any questions you may have about how to use Zefdavir 100

Oral Solution.

Uses of Zefdavir 100 in details

There are specific as well as general uses of a drug or medicine. A medicine can be used to prevent a disease, treat a disease over a period or cure a disease. It can also be used to treat the particular symptom of the disease. The drug use depends on the form the patient takes it. It may be more useful in injection form or sometimes in tablet form. The drug can be used for a single troubling symptom or a life-threatening condition. While some medications can be stopped after few days, some drugs need to be continued for prolonged period to get the benefit from it.

Use: Labeled Indications

Chronic hepatitis B (Zefdavir 100 HBV): Treatment of chronic hepatitis B associated with evidence of hepatitis B viral replication and active liver inflammation

Limitations of use: Use only when an alternative antiviral agent with a higher genetic barrier to resistance is not available or appropriate. Zefdavir 100-HBV has not been evaluated in patients coinfected with HIV, hepatitis C virus, or hepatitis delta virus; with decompensated liver disease; or in liver transplant recipients.

HIV-1 infection, treatment (Zefdavir 100): Treatment of HIV-1 in combination with other antiretroviral agents

Off Label Uses

HIV-1 nonoccupational postexposure prophylaxis

Based on the Centers for Disease Control and Prevention, US Department of Health and Human Services updated guidelines for antiretroviral postexposure prophylaxis after sexual, injection drug use, or other nonoccupational exposure to HIV, Zefdavir 100 (in conjunction with other antiretrovirals) is an effective and recommended treatment option for postexposure prophylaxis of HIV-1 infection following nonoccupational exposure (nPEP) in individuals exposed to blood, genital secretions, or other potentially infectious body fluids that may contain HIV when that exposure represents a substantial risk for HIV transmission.

Prevention of perinatal HIV transmission

Based on the Health and Human Services (HHS) Perinatal HIV Guidelines, Zefdavir 100, in combination with zidovudine and nevirapine, is a recommended regimen for empiric therapy to reduce the risk of perinatal transmission of HIV in HIV-exposed infants at higher risk of HIV-acquisition, including those born to HIV-infected women who did not receive antepartum or intrapartum antiretroviral drugs (ARV), who received only intrapartum ARV drugs, or who received antepartum and intrapartum ARV drugs but had a detectable viral load near delivery (particularly if delivery was vaginal), or mothers with acute HIV infection during pregnancy or breastfeeding. Empiric therapy with this combination provides prophylaxis against HIV acquisition and provides early treatment if HIV infection is later confirmed.

Zefdavir 100 description


Zefdavir 100 also contains the following excipients: Tablet Core: Microcrystalline cellulose, sodium starch glycollate and magnesium stearate. Tablet Film-Coat: Hypromellose, titanium dioxide, macrogol 400, polysorbate 80 and synthetic yellow and red iron oxides.

Zefdavir 100 dosage

Recommended Dosage For Adult Patients

The recommended dosage of Zefdavir 100 in HIV-1-infected adults is 300 mg daily, administered as either 150 mg taken orally twice daily or 300 mg taken orally once daily with or without food. If Zefdavir 100 is administered to a patient infected with HIV-1 and HBV, the dosage indicated for HIV-1 therapy should be used as part of an appropriate combination regimen.

Recommended Dosage For Pediatric Patients

The recommended dosage of Zefdavir 100 oral solution in HIV-1-infected pediatric patients aged 3 months and older is 4 mg per kg taken orally twice daily or 8 mg per kg taken orally once daily (up to a maximum of 300 mg daily), administered in combination with other antiretroviral agents. Consider HIV-1 viral load and CD4+ cell count/percentage when selecting the dosing interval for patients initiating treatment with oral solution.

Zefdavir 100 scored tablet is the preferred formulation for HIV-1-infected pediatric patients who weigh at least 14 kg and for whom a solid dosage form is appropriate. Before prescribing Zefdavir 100 scored tablets, pediatric patients should be assessed for the ability to swallow tablets. For patients unable to safely and reliably swallow Zefdavir 100 tablets, the oral solution formulation should be prescribed. The recommended oral dosage of Zefdavir 100 tablets for HIV-1-infected pediatric patients is presented in Table 1.

Table 1: Dosing Recommendations for Zefdavir 100 Scored (150-mg) Tablets in Pediatric Patients

Weight (kg) Once-Daily Dosing Regimen Patients may alternatively take one 300-mg tablet, which is not scored.

Patients With Renal Impairment

Dosing of Zefdavir 100 is adjusted in accordance with renal function. Dosage adjustments are listed in Table 2.

Table 2: Adjustment of Dosage of Zefdavir 100 in Adults and Adolescents (Greater than or Equal to 25 kg) in Accordance with Creatinine Clearance

Creatinine Clearance (mL/min) Recommended Dosage of Zefdavir 100
≥50 150 mg twice daily or 300 mg once daily
30-49 150 mg once daily
15-29 150 mg first dose, then 100 mg once daily
5-14 150 mg first dose, then 50 mg once daily
< 5 50 mg first dose, then 25 mg once daily

No additional dosing of Zefdavir 100 is required after routine (4-hour) hemodialysis or peritoneal dialysis.

Although there are insufficient data to recommend a specific dose adjustment of Zefdavir 100 in pediatric patients with renal impairment, a reduction in the dose and/or an increase in the dosing interval should be considered.

How supplied

Dosage Forms And Strengths

Zefdavir 100 Scored Tablets

Zefdavir 100 scored tablets contain 150 mg of Zefdavir 100. The tablets are white, diamond-shaped, scored, film-coated tablets debossed with “GX CJ7” on both sides.

Zefdavir 100 Tablets

Zefdavir 100 tablets contain 300 mg of Zefdavir 100. The tablets are gray, modified diamond-shaped, film-coated, and engraved with “GX EJ7” on one side and plain on the reverse side.

Zefdavir 100

Oral Solution

Zefdavir 100 oral solution contains 10 mg of Zefdavir 100 per 1 mL. The solution is a clear, colorless to pale yellow, strawberry-banana flavored liquid.

Storage And Handling

Zefdavir 100 scored tablets contain 150 mg of Zefdavir 100, are white, diamond-shaped, film-coated, and debossed with “GX CJ7” on both sides. Packaged as follows:

Bottle of 60 tablets (NDC 49702-203-18) with child-resistant closure.

Zefdavir 100 tablets contain 300 mg of Zefdavir 100, are gray, modified diamond-shaped, film-coated, and engraved with “GX EJ7” on one side and plain on the reverse side. Packaged as follows:

Bottle of 30 tablets (NDC 49702-204-13) with child-resistant closure.

Recommended Storage

Store Zefdavir 100 tablets at 25°C (77°F); excursions permitted to 15° to 30°C (59° to 86°F).

Zefdavir 100 oral solution is a clear, colorless to pale yellow, strawberry-banana-flavored liquid. Each mL of the solution contains 10 mg of Zefdavir 100. Packaged as follows:

Plastic bottle of 240 mL (NDC 49702-205-48) with child-resistant closure. This product does not require reconstitution.

Store in tightly closed bottles at 25°C (77°F).

Manufactured for: ViiV Healthcare, Research Triangle Park, NC 27709 by: GlaxoSmithKline, Research Triangle Park, NC 27709. Manufactured under agreement from Shire Pharmaceuticals Group plc, Basingstoke, UK. Revised: July 2016

Zefdavir 100 interactions

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What other drugs will affect Zefdavir 100?


Interaction studies have only been performed in adults.

The likelihood of metabolic interactions is low due to limited metabolism and plasma protein binding and almost complete renal elimination of unchanged substance.

Zefdavir 100 is predominantly eliminated by active organic cationic secretion. The possibility of interactions with other medicinal products administered concurrently should be considered, particularly when their main route of elimination is active renal secretion via the organic cationic transport system e.g. trimethoprim. Other medicinal products (e.g. ranitidine, cimetidine) are eliminated only in part by this mechanism and were shown not to interact with Zefdavir 100.

Substances shown to be predominately excreted either via the active organic anionic pathway, or by glomerular filtration are unlikely to yield clinically significant interactions with Zefdavir 100.

Administration of trimethoprim/sulphamethoxazole 160 mg/800 mg increased Zefdavir 100 exposure by about 40%. Zefdavir 100 had no effect on the pharmacokinetics of trimethoprim or sulphamethoxazole. However, unless the patient has renal impairment, no dosage adjustment of Zefdavir 100 is necessary.

A modest increase in Cmax (28%) was observed for zidovudine when administered with Zefdavir 100, however overall exposure (AUC) was not significantly altered. Zidovudine had no effect on the pharmacokinetics of Zefdavir 100.

Zefdavir 100 has no pharmacokinetic interaction with alpha-interferon when the two medicinal products are concurrently administered. There were no observed clinically significant adverse interactions in patients taking Zefdavir 100 concurrently with commonly used immunosuppressant medicinal products (e.g. cyclosporin A). However, formal interaction studies have not been performed.

Emtricitabine: Due to similarities, Zefdavir 100 should not be administered concomitantly with other cytidine analogues, such as emtricitabine. Moreover, Zefdavir 100 should not be taken with any other medicinal products containing Zefdavir 100.

Cladribine: In vitro Zefdavir 100 inhibits the intracellular phosphorylation of cladribine leading to a potential risk of cladribine loss of efficacy in case of combination in the clinical setting. Some clinical findings also support a possible interaction between Zefdavir 100 and cladribine. Therefore, the concomitant use of Zefdavir 100 with cladribine is not recommended.

Zefdavir 100 side effects

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What are the possible side effects of Zefdavir 100?

Clinical Trial Data: In clinical studies of patients with chronic hepatitis B, Zefdavir 100 was well tolerated. The incidence of adverse events and laboratory abnormalities [with the exception of elevations of ALT and creatinine phosphokinase (CPK), see table] were similar between placebo and Zefdavir 100-treated patients. The most common adverse events reported were malaise and fatigue, respiratory tract infections, headache, abdominal discomfort and pain, nausea, vomiting and diarrhoea.

Adverse reactions are listed as follows by system organ class and frequency. Frequency categories are only assigned to those adverse reactions considered to be at least possibly causally related to Zefdavir 100. Frequencies are defined as: Very Common (≥1/10), common (≥1/100, <1/10), uncommon (≥1/1,000, <1/100), rare (≥1/10,000, <1/1,000) and very rare (<1/10,000).

The frequency categories assigned to the following adverse reactions are estimates: For most events, suitable data for calculating incidence are not available. Very common and common adverse drug reaction frequency categories were determined from clinical trial data and the background incidence in placebo groups was not taken into account. Adverse drug reactions identified through post-marketing surveillance were categorized as rare or very rare.

Hepatobiliary Disorders: Very Common: Elevations of ALT.

Elevations in ALT were more common in posttreatment patients treated with Zefdavir 100 than placebo. In controlled trials in patients with compensated liver disease, however, there was no appreciable difference posttreatment in clinically severe ALT elevations associated with bilirubin elevations and/or signs of hepatic insufficiency, between Zefdavir 100- and placebo-treated patients. The relationship of these recurrent hepatitis events to Zefdavir 100 treatment or to the previous underlying disease is uncertain.

Musculoskeletal and Connective Tissue Disorders: Common: Elevations of CPK.

Post-Marketing Data: In addition to adverse events reported from clinical trials, the following events have been identified during post-approval use of Zefdavir 100.

Blood and Lymphatic System Disorders: Very Rare: Thrombocytopenia.

Musculoskeletal and Connective Tissue Disorders: Common: Muscle disorders, including myalgia and cramps. Very Rare: Rhabdomyolysis.

In patients with HIV infection, cases of pancreatitis and peripheral neuropathy (or paresthesia) have been reported, although no relationship to treatment with Zefdavir 100 has been clearly established. In patients with chronic hepatitis B, there was no observed difference in incidence of these events between placebo- and Zefdavir 100-treated patients.

Cases of lactic acidosis, usually associated with severe hepatomegaly and hepatic steatosis, have been reported with the use of combination nucleoside analogue therapy in patients with HIV. There have been occasional reports of these adverse events in hepatitis B patients with decompensated liver disease, however, there is no evidence that these events were related to treatment with Zefdavir 100.

Zefdavir 100 contraindications

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What is the most important information I should know about Zefdavir 100?

You should not take Zefdavir 100 if you are allergic to it.

The Zefdavir 100 brand of Zefdavir 100 (for treating HIV) should not be taken together with any HIV combination medicine that contains Lamivudine or emtricitabine. This includes Atripla, Combivir, Complera, Emtriva, Epzicom, Trizivir, and Truvada.

The Zefdavir 100-HBV brand of Zefdavir 100 (for treating hepatitis B) should not be taken together with any other medication that contains Lamivudine, which includes Combivir, Zefdavir 100, Epzicom, and Trizivir.

Before taking Zefdavir 100, tell your doctor if you have kidney disease, liver disease, a history of pancreatitis, or if you have used a medicine similar to Zefdavir 100 in the past, such as abacavir (Ziagen), didanosine (Videx), emtricitabine (Atripla, Complera, Emtriva, Truvada), stavudine (Zerit), tenofovir (Viread), zalcitabine (Hivid), or zidovudine (Retrovir).

Some people develop lactic acidosis while taking Zefdavir 100. Early symptoms may get worse over time and this condition can be fatal. Get emergency medical help if you have even mild symptoms such as: muscle pain or weakness, numb or cold feeling in your arms and legs, trouble breathing, stomach pain, nausea with vomiting, fast or uneven heart rate, dizziness, or feeling very weak or tired.

If you have hepatitis B you may develop liver symptoms after you stop taking this medication, even months after stopping. Your doctor may want to check your liver function for several months after you stop using Zefdavir 100. Visit your doctor regularly.

Zefdavir 100 can also cause severe or life-threatening effects on your liver or pancreas. Call your doctor at once if you have any of these symptoms while taking Zefdavir 100: severe pain in your upper stomach spreading to your back, nausea and vomiting, fast heart rate, itching, loss of appetite, dark urine, clay-colored stools, or jaundice (yellowing of the skin or eyes).

Zefdavir 100 tablets and liquid contain a higher dose of Zefdavir 100 than Zefdavir 100-HBV. Each time you get a refill of this medication, be sure you have received the correct brand to treat your condition.

Active ingredient matches for Zefdavir 100:

Lamivudine in Vietnam.

Unit description / dosage (Manufacturer)Price, USD
Zefdavir 100 100 mg x 3 Blister x 10 Tablet
Zefdavir 100 100 mg x 1 Bottle x 30 Tablet

List of Zefdavir 100 substitutes (brand and generic names):

Tablets; Oral; Lamivudine 150 mg (Croslands (Ranbaxy Laboratories Ltd)
Virolam 100 mg Tablet (Croslands (Ranbaxy Laboratories Ltd)$ 0.12
Virolam 150 mg Tablet (Croslands (Ranbaxy Laboratories Ltd)$ 0.16
VIROLAM tab 100 mg x 10's (Croslands (Ranbaxy Laboratories Ltd)$ 1.21
VIROLAM tab 150 mg x 10's (Croslands (Ranbaxy Laboratories Ltd)$ 1.60
Solution; Oral; Lamivudine 25 mg / 5 ml (GlaxoSmithKline)
Tablet, Film-Coated; Oral; Lamivudine 100 mg (GlaxoSmithKline)
Tablet; Oral; Lamivudine 100 mg (GlaxoSmithKline)
Zeffix 100 mg x 28's (GlaxoSmithKline)
Zeffix 100 mg x 2 x 14's (GlaxoSmithKline)
Zeffix 100 mg x 6 x 14's (GlaxoSmithKline)
Zeffix 100 mg x 28 Tablet (GlaxoSmithKline)
Zeffix 100 mg x 14's (GlaxoSmithKline)$ 56.15
Tablets, Film-Coated; Oral; Lamivudine 100 mg (GlaxoSmithKline)
Tablets; Oral; Lamivudine 100 mg (GlaxoSmithKline)
Zeffix film-coated tab 100 mg 28's (GlaxoSmithKline)
Zeffix FC tab 100 mg 2 x 14's (GlaxoSmithKline)
Zeffix FC tab 100 mg 6 x 14's (GlaxoSmithKline)
Zeffix FC tab 100 mg 28's (GlaxoSmithKline)
Zeffix film-coated tab 100 mg 28's (GlaxoSmithKline)
Zefix 50 mg Tablet (Meditek Life Sciences Pvt.Ltd)$ 0.09
Zefix 100 mg Tablet (Meditek Life Sciences Pvt.Ltd)$ 0.16
Zefix 200+LB Tablet (Meditek Life Sciences Pvt.Ltd)$ 0.30
Zefix 200 mg Tablet (Meditek Life Sciences Pvt.Ltd)$ 0.27
ZEFIX 200MG TABLET 1 strip / 10 tablets each (Meditek Life Sciences Pvt.Ltd)$ 1.79
Zefix 200mg Tablet (Meditek Life Sciences Pvt.Ltd)$ 0.18
Zeraffic tab 100 mg 2 x 14's (Jeil Pharm)
Zidolam N 150+300+200 Tablet (Genx (Hetero Healthcare Ltd))$ 0.38
ZIDOLAM N 150 MG/300 MG/200 MG TABLET 1 strip / 10 tablets each (Genx (Hetero Healthcare Ltd))$ 3.33
ZIDOLAM N 150 MG/300 MG/200 MG TABLET 1 packet / 60 tablets each (Genx (Hetero Healthcare Ltd))$ 10.95
Zymmex 100 mg x 3 Blister x 10 Tablet
Zymmex 100 mg x 10 Blister x 10 Tablet


  1. DailyMed. "LAMIVUDINE: DailyMed provides trustworthy information about marketed drugs in the United States. DailyMed is the official provider of FDA label information (package inserts).". https://dailymed.nlm.nih.gov/dailyme... (accessed September 17, 2018).
  2. PubChem. "lamivudine". https://pubchem.ncbi.nlm.nih.gov/com... (accessed September 17, 2018).
  3. DrugBank. "lamivudine". http://www.drugbank.ca/drugs/DB00709 (accessed September 17, 2018).


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Information checked by Dr. Sachin Kumar, MD Pharmacology

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