Zalcitabine is a so-called antiviral drug for oral administration. It is classified as a member of the nucleoside reverse transcriptase inhibitor (NRTI) group of drugs and is used in the antiviral therapy of HIV infection.
What is zalcitabine?
Zalcitabine belongs to the NRTI group of drugs, which are antiretroviral agents. It was first produced by Jerome Horwitz in the 1960s in connection with cancer research. Further development as a drug for the treatment of HIV was later undertaken by the U.S. National Cancer Institute (NCI). In 1992, the drug was approved for monotherapy, and in 1996 also for combination therapy. Sales in Germany were discontinued on December 31, 2006, due to the introduction of newer forms of therapy. Zalcitabine was used to treat patients with HIV type 1. From a structural point of view, it is a derivative, i.e. a modified chemical compound of the nucleoside cytidine. Furthermore, zalcitabine is an analog of deoxycytidine. Zalcitabine is a white crystalline powder that is soluble in water.
Pharmacologic effects on the body and organs
Zalcitabine was distributed in the form of tablets. After ingestion as well as absorption, the drug is converted into the pharmacologically active 5′-triphosphate. The conversion is followed by incorporation into the viral genome. Since the hydroxyl group is missing in the active substance molecule, the DNA synthesis of the HI viruses is immediately inhibited. Zalcitabine is transported almost exclusively freely in the blood; it is not bound to plasma proteins. The half-life of zalcitabine is about two hours, and its biological value is 80 percent. However, the body uses only about 30 percent of the absorbed active ingredient, while the rest is excreted renally – i.e., via the kidneys – in unchanged form.
Medical use and use for treatment and prevention.
Zalcitabine was used until late 2006 as part of combination therapy in patients with type 1 HIV. During infection, the HI viruses multiply in the cells of the body. The newly formed viruses are eventually released and spread throughout the body. This leads to infection of other cells, and the disease continues to spread to uninfected cells. Due to an enzyme, zalcitabine ensures that no new DNA of the virus can form. Until sales were discontinued, zalcitabine was considered an alternative for patients who could not tolerate zidovudine or for whom treatment with zidovudine was ineffective. In these patients, zalcitabine showed the same effect as didanosine. For zalcitabine, as for all other available drugs for HIV patients, it is not possible to cure the infection. Only the progression of the disease can be delayed.
Risks and side effects
Zalcitabine may cause side effects. These manifest themselves in different ways from patient to patient. Typical side effects of the antiviral are mainly headache, diarrhea, constipation, nausea, loss of appetite, a change in body fat percentage, itching, or even fatigue. A doctor must be consulted immediately if side effects due to zalcitabine occur, such as severe allergic reactions (e.g., difficulty breathing, swelling of the mouth and face or lips, hives), cramps, feeling cold, heart problems (e.g. (e.g., heartbeat too fast or too slow), drowsiness and dizziness, liver inflammation, numbness or pain in the limbs (arms, legs, hands, feet), ulcers in the mouth and throat, severe nausea and vomiting, or severe difficulty swallowing. Side effects such as fever, bone and joint pain, and neuropathies (diseases of the peripheral nervous system) have also occurred during treatment with zalcitabine. To avoid interactions, do not take drugs whose active ingredients can cause neuropathies. Simultaneous intake of lamivudine inhibits the effect of zalcitabine. The use of zalcitabine is not indicated in existing diseases of the liver, known diseases of the peripheral nervous system, as well as existing hypersensitivity to the active substance. During treatment, the patient’s blood count must be checked regularly by the physician. This also applied to patients with existing pancreatitis and in patients with increased alcohol consumption.
