Videx

Videx is an antiviral drug with a direct type of therapeutic effect. [1]

Didanosine, when tested in vitro, inhibits the reproduction of HIV within cultured human cells along with cell lines. Once inside the cell, the element is enzymatically converted to its metabolic component, dideoxyadenosine-3-phosphate. In the reproduction of a nucleic acid virus, the use of 2s3'-dideoxynucleoside prevents chain prolongation, thereby slowing down the reproduction process. In addition, ddATP slows down the action of HIV reverse transcriptase, destroying the binding of the provirus DNA. [2]

Indications Videx

It is used for HIV infection (in combination with other antiretroviral drugs). [3]

Release form

The release of the medication is realized in capsules - 10 pieces inside a cell package; inside a pack - 3 such packages.

Pharmacokinetics

It takes about 120 minutes for didanosine to obtain plasma Cmax values; in this case, the Cmax indicator itself is in direct proportion to the size of the received portion of the drug.

The average level of didanosine inside the cerebrospinal fluid is equal to 21% of the simultaneously recorded plasma values of the substance.

Capsules are used on an empty stomach, since their introduction with food reduces the Cmax values by 46%, and the AUC level by 19%.

In humans, the metabolic processes of didanosine have been studied rather poorly. Based on experimental data, it is believed that in humans they are realized through the metabolism of internal purines.

When administered orally, the half-life is on average 1.6 hours (for tablets), but because the absorption rate of the substance from capsules is much lower, its half-life in this case will be approximately 50% longer. The excretion of the drug in the urine is approximately 20% of the orally consumed portion.

The index of intrarenal clearance is equal to 50% of its total values (0.8 L per minute) - this confirms the active processes of CF and secretion through the tubules during the renal excretion of didanosine. After 1 month of taking the medicine internally, didanosine did not accumulate inside the body.

Application to persons with renal dysfunction.

When administered orally, the half-life term increases on average by at least 1.4 hours (in the case of normal renal function) and by a maximum of 4.1 hours (if severe dysfunction is observed). Inside the dialysis peritoneal fluid, the medication is not recorded, but during hemodialysis, after 3-4 hours, the plasma level of didanosine was within 0.6-7.4% of the accepted dosage.

In the case of renal dysfunction (CC values below 60 ml per minute / 1.73 m2), the dose of the drug is selected personally.

Use in people with hepatic dysfunction.

Metabolic processes of didanosine are determined by the severity of hepatic dysfunction, which may require a decrease in the dosage of Videx.

Dosing and administration

The medicine is taken 1-2 times a day. The capsules are swallowed whole without chewing. They should be consumed on an empty stomach (either half an hour before or 2 hours after a meal), drinking at least 0.1 liters of plain water (to improve the absorption of drugs). It is forbidden to open the capsules, as this can reduce their medicinal effect.

The size of the daily portion is determined by the patient's weight:

• weight> 60 kg - 0.4 g, once a day;
• weight <60 kg - 0.25 g, once a day.

There were no special studies of the introduction of capsules in pediatrics, but when using other forms of drug release, the required daily dosage (calculated depending on the area of the body surface) was 0.24 g / m2 (0.18 g / m2 in combination with zidovudine).

For adults with renal dysfunction, it is necessary to reduce the dosage or prolong the interval between Videx injections (taking into account the CC values).

With a weight> 60 kg:

• the CC level is> 60 ml per minute / 1.73 m2 - 0.4 g per day;
• in the range of 30-59 ml per minute / 1.73 m2 - 0.25 g per day;
• within 10-29 ml per minute / 1.73 m2 - use a different form of medication.
• With a weight <60 kg:
• CC values are> 60 ml per minute / 1.73 m2 - 0.25 g per day;
• indicators in the range of 30-59 ml per minute / 1.73 m2 - the drug is administered in a different form of release.

Persons on hemodialysis need to consume the daily portion after the procedure. No additional dosage is required.

Aged people.

Before using drugs, you need to check the renal function, because this group has a high risk of having a failure of renal function, which requires the use of a personalized dosage.

Individuals with hepatic dysfunction.

A decrease in the dose of drugs is required, but there are no definite indications for changing the dosage. During therapy, you need to monitor the values of liver enzymes. If there is a clinically noticeable increase in their values, therapy is stopped. A rapid increase in aminotransferase parameters may require a complete discontinuation of therapy with the introduction of any nucleoside analogs.

Skipping drug intake.

If you accidentally skip the time of using the medication, then use the usual dosage (it is forbidden to double the portion as compensation for the previously missed one).

• Application for children

In pediatrics, the medicine is used in a different form of release.

Use Videx during pregnancy

When tested with animals, didanosine showed no fetotoxic or embryotoxic or teratogenic effects.

Pregnant women are prescribed medication only under strict indications and in situations where the benefits of therapy are more likely than the risk of negative consequences for the fetus.

Women with HIV infection should not breastfeed, as this can lead to infection of the baby.

Contraindications

A contraindication is severe intolerance to didanosine or other elements of the drug.

Side effects Videx

When treating HIV-infected patients, it is extremely difficult to distinguish between the negative manifestations associated with taking Videx and the negative effect of other drugs used in combination, as well as negative symptoms that are associated with the disease itself. Among the side signs encountered:

• dysfunction of the NS: often there are neurological manifestations of the peripheral type (among them neuropathies), as well as headaches;
• digestive problems: diarrhea is mainly observed. Bloating, nausea, xerostomia, abdominal pain, vomiting, liver failure and hepatitis also develop quite often;
• lesions of the subcutaneous layers with the epidermis: rashes often appear;
• systemic disorders: asthenia or fatigue;
• metabolic disorders: diabetes, hyper- or hypoglycemia, and lactic acidosis;
• problems with the visual organs: depigmentation of the retinal type, dryness of the ocular mucosa and neuritis affecting the optic nerve;
• immune disorders: anaphylactic symptoms;
• infections: sialoadenitis;
• other signs: chills, arthralgia, alopecia, anemia, anaphylactoid manifestations, anorexia and myalgia, and in addition, inflammation affecting the salivary glands, rhabdomyolysis, thrombocyto- or leukopenia, myopathy, hyperbilirubinemia and increased blood values of lactic acid;
• change in test readings: an increase in serum values of alkaline phosphatase, ALT with AST, lipase and amylase.

Overdose

Clinical symptoms of overdose include hyperuricemia, pancreatitis, hepatic dysfunction, polyneuropathy and diarrhea.

In case of unintentional use of a portion exceeding the daily dose, gastric lavage with water and intake of activated charcoal are performed. There is no antidote for didanosine. With significant poisoning, hepatic dysfunction and hyperuricemia were observed. With such disorders, hemodialysis is performed (a 3-4-hour session leads to a decrease in the level of didanosine by 20-30%), and in addition, symptomatic actions.

Interactions with other drugs

The combined systematic use of the drug together with ganciclovir (or taking didanosine 2 hours before ganciclovir) leads to prolongation of the term of stay of didanosine inside the blood plasma up to 111% on average.

The combination of Videx with itraconazole or ketoconazole prolonged the term of intraplasmic stay of didanosine and its parameters by 30%.

The use of the drug in conjunction with substances that can cause pancreatitis or polyneuropathy may increase the likelihood of developing the described toxic symptoms. Patients using such drug combinations must be very closely monitored.

The introduction of the drug in combination with tenofovir increases the systemic excretion of the former and its average values within the urine.

Storage conditions

Videx must be kept in a place protected from the penetration of small children. Temperature values - no more than 25 ° C.

Shelf life

Videx can be used within a 24-month term from the date of manufacture of the drug.

Analogs

Analogs of the drug are Fadinosin with Didanosine.