Retrovir

Retrovir contains the active ingredient zidovudine.

This component, penetrating into the cell, participates in metabolic processes with the help of kinases present in it, being converted into 5-triphosphate (TF). Zidovudine-TF is a substance that competitively slows down the reverse viral HIV transcriptase. The antiviral effect of the drug develops according to the principle of its passage in the form of monophosphate into the DNA of the viral chain and subsequent slowing down of replication processes. [ 1 ]

Indications Retrovir

It is used in the process of antiretroviral treatment in people infected with HIV. In addition, it can be prescribed to women with HIV+ status during pregnancy beyond 14 weeks.

Release form

The medicinal substance is released in capsules - 100 pieces in a bottle; in a pack - 1 such bottle. In addition, the capsules can be packed in cell plates - 10 pieces each; inside the box - 10 such plates.

Pharmacokinetics

Zidovudine has good absorption in the gastrointestinal tract; the level of bioavailability is within 60-70%. The intraplasmic Cmax values after oral administration of the drug in a dose of 5 mg/kg at 4-hour intervals are equal to 7.1 microns.

After intravenous injection of the drug, the half-life is 1.1 hours, and the mean total clearance is 27.1 ml/minute/kg; the distribution volume is 1.61/kg. The clearance rate of zidovudine is significantly higher than the CC value, which demonstrates the significant role of tubular secretion in excretion processes. [ 2 ]

Zidovudine is able to cross the placenta and is registered in the fetal blood with amniotic fluid. Protein synthesis is quite weak – within 34-38%. [ 3 ]

Dosing and administration

Therapy using Retrovir is only possible under the supervision of a doctor who has experience in treating people with HIV+ status.

For an adult and a child weighing over 30 kg, the prescribed dose is 0.5-0.6 g of the substance (the dosage is divided into 2 doses).

A child whose weight is between 21-30 kg is required to take 0.2 g of the drug 2 times a day, along with other antiretroviral agents.

People weighing 14-21 kg are prescribed 0.1 g of the medication (1 capsule in the morning) and 0.2 g (2 capsules in the evening).

For a child weighing 8-14 kg, the required dosage is 0.1 g (1 capsule 2 times a day).

For infants weighing less than 8 kg, as well as those who cannot swallow a capsule, the medicine should be used in the form of a solution for oral administration.

Use Retrovir during pregnancy

Zidovudine is able to overcome the hematoplacental barrier, which is why the drug can be used during pregnancy only after the 14th week. It can be administered earlier only if there are vital indications.

Contraindications

Among the contraindications:

• administration to individuals with diagnosed intolerance to zidovudine;
• use in people with abnormally low neutrophil counts (less than 0.75x10 9/l) or pathologically low hemoglobin levels (less than 7.5 g/l);
• appointment during breastfeeding.

Side effects Retrovir

When Retrovir is administered, disorders of the circulatory system may develop, including leukopenia, neutroopenia, thrombocytoopenia, or pancytopenia, lactic acidosis, and aplastic anemia.

In addition, patients may experience the following side effects:

• depression, seizures, headaches, severe anxiety, decreased mental performance, sleep disorders and paresthesia;
• cardiomyopathy;
• dyspnea or cough;
• dyspeptic disorders, bloating, taste changes and pancreatitis;
• allergy symptoms and hives.

Overdose

The introduction of drugs in increased doses leads to the potentiation of side effects.

To stabilize the patient's condition, it is necessary to perform gastric lavage and carry out symptomatic measures.

Interactions with other drugs

Lamivudine causes a moderate increase in zidovudine Cmax (28%) without affecting AUC. The pharmacokinetic parameters of lamivudine are not altered by zidovudine.

Probenecid reduces glucuronidation and increases the AUC with the half-life term of zidovudine. Use of probenecid results in decreased intrarenal excretion of glucuronide with zidovudine.

Because ribavirin is an antagonist of zidovudine, these drugs are not used in combination.

Co-administration with rifampicin causes a decrease in zidovudine AUC by approximately 48±34% (there is no information regarding the clinical significance of this change).

Zidovudine inhibits the phosphorylation processes of stavudine inside cells.

The drug reduces the blood level of phenytoin (if they are combined, the plasma levels of the latter should be monitored).

Aspirin, lorazepam, codeine with paracetamol, naproxen and morphine, as well as cimetidine, isoprinosine with indomethacin, oxazepam and ketoprofen with dapsone and clofibrate can interfere with the metabolic processes of zidovudine (competitively slow down glucuronidation or inhibit intrahepatic microsomal metabolism processes). Therefore, such combinations should be used with caution.

Concomitant administration of Retrovir and nephrotoxic or myelotoxic agents (especially in emergency care), including flucytosine, vincristine and pentamidine with ganciclovir, as well as amotericin, doxorubicin and dapsone with vinblastine, interferon, co-trimoxazole and pyrimethamine, increases the likelihood of adverse effects of the former (it is necessary to monitor kidney function and blood counts, and reduce the dosage if necessary).

Radiation therapy potentiates the myelosuppressive activity of zidovudine.

Storage conditions

Retrovir should be stored in a place closed to small children, light and moisture. Temperature values are no more than 30°C.

Shelf life

Retrovir is approved for use for a 5-year period from the date of manufacture of the pharmaceutical product.

Analogues

The analogs of the drug are Lazid, Zidolam and Virocomb with Lamihop Z, and also Duovir, Lamivudine, Zovilam and Combivudine. The list also includes Zidovir, Trizivir, Combivir with Zidovudine, Nardin and Lazivudine.