Zefix
Zefix Uses, Dosage, Side Effects, Food Interaction and all others data.
Zefix is a synthetic nucleoside analogue. Zefix is phosphorylated intracellularly to lamivudine triphosphate. Incorporation of the monophosphate form into viral DNA occurs by hepatitis B virus (HBV) polymerase. As a result DNA chain is terminated. Zefix triphosphate also inhibits the RNA and DNA-dependent DNA polymerase activities of HIV-1 reverse transcriptase (RT). Zefix triphosphate is a very weak inhibitor of mammalian alpha, beta, and gamma-DNA polymerases.
Zefix is a nucleoside reverse transcriptase inhibitor (NRTI) with activity against Human Immunodeficiency Virus Type 1 (HIV-1) and hepatitis B (HBV) to disrupt viral DNA synthesis. When phosphorylated, lamivudine can form active metabolites that compete for incorporation into viral DNA. Via DNA incorporation, lamivudine metabolites competitively inhibit the activity of the HIV reverse transcriptase enzyme and act as a chain terminator of DNA synthesis. Due to the lack of a 3'-OH group, incorporated nucleoside analogues prevent the formation of a 5' to 3' phosphodiester linkage that is essential for DNA chain elongation.
| Trade Name | Zefix |
| Availability | Prescription only |
| Generic | Lamivudine |
| Lamivudine Other Names | Lamivudin, Lamivudina, Lamivudine, Lamivudinum |
| Related Drugs | Biktarvy, Truvada, tenofovir, entecavir, ritonavir, zidovudine, abacavir, emtricitabine, Vemlidy, Complera |
| Type | Tablet |
| Formula | C8H11N3O3S |
| Weight | Average: 229.256 Monoisotopic: 229.052111923 |
| Protein binding | <36% bound to plasma protein. |
| Groups | Approved, Investigational |
| Therapeutic Class | Hepatic viral infections (Hepatitis B) |
| Manufacturer | Glaxosmithkline philippines, inc, |
| Available Country | Philippines |
| Last Updated: | September 19, 2023 at 7:00 am |
Uses
Zefix is used for the treatment of chronic hepatitis B associated with evidence of hepatitis B viral replication and active liver inflammation.
Zefix is also used to associated treatment for these conditions: Hepatitis B Chronic Infection, Human Immunodeficiency Virus (HIV) Infections
How Zefix works
Zefix is a synthetic nucleoside analogue and is phosphorylated intracellularly to its active 5'-triphosphate metabolite, lamivudine triphosphate (L-TP). This nucleoside analogue is incorporated into viral DNA by HIV reverse transcriptase and HBV polymerase, resulting in DNA chain termination.
Dosage
Zefix dosage
The recommended oral dose of Zefix for the treatment of chronic hepatitis B in adults is 100 mg once daily.
Side Effects
Several serious adverse events reported with lamivudine (lactic acidosis and severe hepatomegaly with steatosis, post treatment exacerbations of hepatitis B, pancreatitis, and emergence of viral mutants associated with reduced drug susceptibility and diminished treatment response). Malaise, fatigue, fever, ENT infections, sore throat, nausea, vomiting, abdominal discomfort, pain, diarrhea, myalgia, arthralgia, headache, skin rashes may occur. Lactic acidosis and severe hepatomegaly with steatosis, have been reported.
Toxicity
The most common reported adverse reactions (incidence ≥15%) in adults were headache, nausea, malaise and fatigue, nasal signs and symptoms, diarrhea, and cough.
Precaution
Patients should be assessed before beginning treatment and during treatment with lamivudine by a physician experienced in the management of chronic hepatitis B.
Interaction
Trimethoprim 160 mg / Sulfamethoxazole 800 mg once daily has been shown to increase lamivudine exposure (AUC). The effect of higher doses of trimethoprim /sulfamethoxazole on lamivudine pharmacokinetics has not been investigated.
Food Interaction
- Take with or without food. Food delays drug absorption, but not to a clinically significant extent.
Zefix Cholesterol interaction
[Major] The reverse transcriptase inhibitors, didanosine (ddI), zalcitabine (ddC), stavudine (d4T) and lamivudine (3TC), may cause pancreatitis.
The incidence is generally low but is approximately 7% with ddI, and up to 15% in pediatric patients given 3TC.
Patients with a history of or known risk factors for pancreatitis, such as alcohol abuse or hypertriglyceridemia, should be monitored closely during therapy with these agents.
Therapy should be discontinued at the first signs or symptoms suggestive of pancreatitis (e.g., nausea, vomiting, abdominal pain, hyperamylasemia with dysglycemia, rising triglycerides, decreasing serum calcium), and preferably permanently discontinued if clinical pancreatitis develops.
Zefix Drug Interaction
Unknown: rosuvastatin, rosuvastatin, raltegravir, raltegravir, ritonavir, ritonavir, acetaminophen, acetaminophen, dolutegravir, dolutegravir, valproic acid, valproic acid, cyanocobalamin, cyanocobalamin, pyridoxine, pyridoxine, ascorbic acid, ascorbic acid, cholecalciferol, cholecalciferol
Zefix Disease Interaction
Volume of Distribution
Apparent volume of distribution, IV administration = 1.3 ± 0.4 L/kg. Volume of distribution was independent of dose and did not correlate with body weight.
Elimination Route
Zefix was rapidly absorbed after oral administration in HIV-infected patients. Absolute bioavailability in 12 adult patients was 86% ± 16% (mean ± SD) for the 150-mg tablet and 87% ± 13% for the oral solution. The peak serum lamivudine concentration (Cmax) was 1.5 ± 0.5 mcg/mL when an oral dose of 2 mg/kg twice a day was given to HIV-1 patients. When given with food, absorption is slower, compared to the fasted state.
Half Life
5 to 7 hours (healthy or HBV-infected patients)
Clearance
- Renal clearance = 199.7 ± 56.9 mL/min [300 mg oral dose, healthy subjects]
- Renal clearance = 280.4 ± 75.2 mL/min [single IV dose, HIV-1-infected patients]
- Total clearance = 398.5 ± 69.1 mL/min [HIV-1-infected patients]
Elimination Route
The majority of lamivudine is eliminated unchanged in urine by active organic cationic secretion. 5.2% ± 1.4% (mean ± SD) of the dose was excreted as the trans-sulfoxide metabolite in the urine. Zefix is excreted in human breast milk and into the milk of lactating rats.
Pregnancy & Breastfeeding use
There is no adequate and well-controlled study in pregnant women. Zefix should be used during pregnancy only if the potential benefits outweigh the risks. Although it is not known if lamivudine is excreted in human milk, there is the potential for adverse effects from lamivudine in nursing infants. Mothers should be instructed not to breast feed if they are receiving lamivudine.
Contraindication
Zefix is contraindicated in patients hypersensitive to any of the components of the product.
Special Warning
It is recommended that doses of Zefix should be adjusted in accordance with renal function. Dosage adjustment of Zefix in accordance with creatinine clearance is as follows:
- CrCl 50 ml/min: 100 mg once daily
- CrCl 30-49 ml/min: 100 mg first dose, then 50 mg once daily
- CrCl 15-29 ml/min: 100 mg first dose, then 25 mg once daily
- CrCl 5-14 ml/min: 35 mg first dose, then 15 mg once daily
- CrCl <5 ml/min: 35 mg first dose, then 10 mg once daily
Use in children: Safety and efficacy of lamivudine for the treatment of chronic hepatitis B in children have not been established.
Storage Condition
Store below 30˚C. Protect from light. Keep out of the reach of children.
Innovators Monograph
You find simplified version here Zefix
Zefix contains Lamivudine see full prescribing information from innovator Zefix Monograph, Zefix MSDS, Zefix FDA label
FAQ
What is Zefix used for?
Zefix is used along with other medications to treat human immunodeficiency virus (HIV) infection in adults and children 3 months of age and older. Zefix is used to treat hepatitis B infection.
How safe is Zefix?
Zefix is generally well tolerated as monotherapy. This study demonstrated that Zefix treatment for up to 6 years has an excellent safety profile in patients with HBeAg-positive compensated liver disease, but patients with long-standing lamivudine-resistant mutations may experience worsening liver disease.
How does Zefix work?
Zefix works by decreasing the amount of HIV and hepatitis B in the blood.
What are the common side effects of Zefix?
Common side effects of Zefix include:
- headache,
- dizziness,
- nausea,
- diarrhea,
- trouble sleeping,
- cough,
- tired feeling,
- runny or stuffy nose, or
- changes in the shape or location of body fat (especially in your arms, legs, face, neck, breasts, and trunk).
Is Zefix safe during pregnancy?
Zefix treatment is safe for chronic HBV-infected pregnant mothers and their fetuses with a gestational age of less than 12 wk or throughout the entire pregnancy.
Is Zefix safe during breastfeeding?
Zefix and tenofovir disoproxil fumarate (TDF) are safe for breastfeeding women, according to a new review of the evidence. Although evidence has accumulated on the efficacy and safety of these two drugs against hepatitis B virus (HBV) during pregnancy, their safety during breastfeeding has not been well studied.
Can I drink alcohol with Zefix?
Side effects from Zefix such as nausea/vomiting, tiredness, loss of appetite, headache, or problems with sleep may get worse if you drink alcohol-containing drinks. Avoid alcohol-containing drinks while taking Zefix.
When is the best time to take Zefix?
Zefix is usually taken once or twice a day with or without food.
How many time can I take Zefix daily?
Zefix is usually taken once a day.
How much Zefix take daily?
Adults, 300 milligrams (mg) once a day or 150 mg 2 times a day. Dose is based on body weight and must be determined by your doctor. The dose is usually 5 milligrams (mg) per kilogram (kg) of body weight taken 2 times a day, or 10 mg per kg once a day.
How effective is Zefix?
a 4-week course of Zefix was safe and effective in suppression of HBV DNA in Chinese HBsAg carriers. The suppression was >90% but reversible. Studies with long-term Zefix administration should be performed to determine if prolonged suppression of HBV DNA can be achieved.
Does Zefix cause liver damage?
Zefix is a very rare cause of clinically apparent drug induced liver injury, but is associated with flares of underlying hepatitis B during therapy or with abrupt withdrawal.
Can I take Zefix for a long time?
Zefix is used for long-term treatment. There can be very serious health consequences if you don't take this drug exactly how your doctor tells you.
How long can one take Zefix?
Patients will stop Zefix for short periods (1 week, and later for 2, 4 and 8 weeks) and be monitored during and for 12 weeks afterwards for aminotransferase levels.
Who should not take Zefix?
You should not take lamivudine if you are allergic to it. You should not take Epivir-HBV (for treating hepatitis B) if you also take other medicine that contains lamivudine or emtricitabine, which includes Atripla, Biktarvy, Cimduo, Combivir, Complera, Descovy, Emtriva, Epzicom, Genvoya, Odefsey, Stribild, Symfi, Triumeq, Trizivir, and Truvada. Tell your doctor if you have ever had: liver disease (especially hepatitis B or C, or a liver transplant); pancreatitis; kidney disease; or diabetes (liquid lamivudine contains 3 to 4 grams of sucrose per dose).
What happens if I miss a dose?
Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time. Get your prescription refilled before you run out of medicine completely.
Can I stop taking Zefix?
Do not stop taking Zefix without talking to your doctor. When your supply of Zefix starts to run low, get more from your doctor or pharmacist. If you miss doses or stop taking Zefix, your condition may become more difficult to treat.
Can I overdose on Zefix?
Seek emergency medical attention. An overdose of Zefix can cause mitochondrial toxicity and lactic acidosis. An intoxication with dolutegravir appears to be relatively harmless. As Triumeq will be used on a regular basis as treatment for patients with HIV-1 infection, these intoxications are expected to be encountered more often.
Can Zefix affect my kidneys?
Effectiveness of Zefix therapy in dialysis patients is comparable with that in patients with normal function of kidney. Zefix treatment is well tolerated and safe in patients with renal insufficiency undergoing hemodialysis and kidney-transplantation.
Can Zefix affects my liver?
Zefix can cause severe or life-threatening effects on your liver or pancreas. Call your doctor at once if you have: severe pain in your upper stomach spreading to your back, nausea, loss of appetite, dark urine, clay-colored stools, or jaundice (yellowing of the skin or eyes).
Does Zefix gain my weight?
Weight gain is a common side effect of antiretroviral therapy (ART).
Does Zefix drugs affect fertility?
Antiretroviral use has been associated with a lower likelihood of conception in a recent prospective cohort study conducted at six US centers.
