The active substance lamivudine is used to treat the immunodeficiency disease AIDS and hepatitis B infections. It belongs to the antiviral drug group.
What is HIV infection?
Lamivudine is a nucleoside reverse transcriptase inhibitor (NRTI) that forms a chemical analog of cytidine, which is one of the nucleosides. The drug is used to treat HIV-1 infections such as AIDS. Although the drug is not able to cure the disease, it does ensure that patients live longer. Lamivudine is manufactured by the British pharmaceutical company GlaxoSmithKline. The antiviral has been used in Germany since 1995. It is now one of the most frequently used nucleoside reverse transcriptase inhibitors in the treatment of HIV infections. It is often combined with abacavir (ABC), which also belongs to the NRTIs.
Pharmacologic action
Lamivudine represents a so-called prodrug. This refers to a drug precursor that is not effective against the viruses. Only within the organism does it undergo conversion into the drug that is actually effective. This has the ability to inhibit the enzyme reverse transcriptase. This effect stops the reproduction of the HI virus. By lowering the number of viruses in the blood, the quantity of special white blood cells such as the CD4-positive T lymphocytes increases at the same time. This process leads to a stronger immune defense of the body. One disadvantage of lamivudine is that the HI virus quickly develops an insensitivity to the single agent due to its high mutability. To avoid this resistance, the antiviral is combined with other active ingredients. In AIDS therapy, for example, three active agents are usually used simultaneously. The enzyme reverse transcriptase is also important for the hepatitis B virus (HBV) to be able to replicate. If lamivudine is administered to treat hepatitis B, this leads to a reduction in the viruses as well as relief of the liver. If chronic hepatitis B is present, the patient receives lamivudine as a single drug. The dosage is lower than for the treatment of HIV infection. The oral bioavailability of lamivudine is classified as high at around 80 percent. There is hardly any influence from the intake of food. The plasma half-life of the active substance is about six hours. Its degradation occurs exclusively via the kidneys.
Medical application and use
Lamivudine is used to combat the human immunodeficiency virus HIV, which causes AIDS. In doing so, the antiviral drug also ensures in some cases that the disease does not break out until a later time. In principle, the drug increases the life expectancy of AIDS patients and improves their quality of life. Lamivudine is also suitable for the treatment of hepatitis B. The drug has a dangerous effect on the immune system. The drug thus counteracts the risk of cirrhosis of the liver. Sometimes the disease can even be cured. If the liver has been transplanted, lamivudine reduces the risk of the organ becoming re-infected with hepatitis B viruses that are still present in the body. The antiviral is administered in the form of tablets. The dose is between 100 and 300 milligrams. A solution can also be taken. As a rule, the patient receives lamivudine once or twice a day, regardless of meals.
Risks and side effects
Although lamivudine is generally well tolerated, several adverse side effects are still within the realm of possibility. These primarily include limitations in performance, fatigue, headache, chills, fever, swelling of the lymph nodes, ]]diarrhea]], nausea, vomiting, digestive problems, general malaise, and flu-like symptoms. Some patients become ill more often with infections. Other side effects may include liver dysfunction, an inflamed liver, an increase in the enzyme amylase, joint problems, muscle pain, and hair loss. In the case of AIDS, deficiency of white blood cells, red blood cells and platelets is more common. Patients who have hepatitis B suffer less frequently. In AIDS patients, a worsening of symptoms is sometimes even possible at the beginning of lamivudine therapy.The reason for this is a reaction of the stronger immune system to germs such as viruses, bacteria, fungi or parasites that are still in the body. Doctors then speak of an immune reactivation syndrome. In most cases, however, the symptoms improve after about four weeks. If hypersensitivity to lamivudine is present, therapy with the active substance must not be carried out. If kidney function is impaired, it may be necessary to adjust the dose. If symptoms such as pain in the hands and feet, tingling, numbness, enlargement of the liver or inflammation of the organ occur, the attending physician must weigh the risks and benefits of therapy carefully. The same applies to the use of lamivudine during pregnancy and breastfeeding. Animal studies have shown harmful effects on the unborn child. However, it is still unclear whether these risks also exist in humans. In principle, it is recommended that lamivudine not be administered in early pregnancy. In case of HIV infection, the patient must refrain from breastfeeding her child. Otherwise there is a risk that the HI virus will be passed on to the child with the mother’s milk. Lamivudine should not be administered to children under three months of age, as there is insufficient knowledge about the effect of the drug on them. In older children, the dosage of the drug depends on their body weight and the course of the disease. Because of the neurotoxic effect of lamivudine, no other drugs that have a similar effect should be administered. These include cisplatin, vincristine, isoniazid, and ethambutol.
