Valcicon, 500 mg 42 pcs

Pharmacodynamics

Valacyclovir is a nucleoside inhibitor of DNA polymerase of herpes viruses. It blocks the synthesis of viral DNA and viral replication. In humans valacyclovir is completely converted to acyclovir and L-valine. In vitro acyclovir has specific inhibitory activity against herpes simplex virus (HPV, Herpes simplex) types 1, 2, varicella zoster virus (VZV, Varicella zoster), CMV, Epstein-Barr virus (VEB) and human herpes virus type 6.

Acyclovir inhibits the synthesis of viral DNA immediately after phosphorylation and transformation into the active form – acyclovir triphosphate. The first stage of phosphorylation occurs with the participation of virus-specific enzymes.

For HPV, VZV and VEB viruses this enzyme is viral thymidine kinase, which is present in virus-affected cells. Partial selectivity of phosphorylation is retained in CMV and is mediated through the product of the phosphotransferase gene UL 97. Activation of acyclovir by a specific viral enzyme largely explains its selectivity.

The process of acyclovir phosphorylation (conversion from mono- to triphosphate) is completed by cellular kinases. Acyclovir triphosphate competitively inhibits viral DNA polymerase and, being a nucleoside analog, is incorporated into viral DNA, which leads to obligate breaking of the chain, cessation of DNA synthesis and, consequently, blocking of viral replication.

In immunocompromised patients, viruses with hypersensitivity to Valacyclovir are extremely rare (less than 0.1%), but may occasionally be found in patients with severe immune impairments, such as those treated with bone marrow transplants, those receiving chemotherapy for malignancies, and those who are HIV-infected.

Resistance is caused by a thymidine kinase deficiency in the virus, which leads to excessive spread of the virus in the host. Sometimes decreased sensitivity to acyclovir is due to the emergence of virus strains with disrupted viral thymidine kinase or DNA polymerase structure. The virulence of these varieties of the virus is similar to that of its wild strain.

Pharmacokinetics

Assimilation. After oral administration valacyclovir is well absorbed from the gastrointestinal tract, quickly and almost completely converted to acyclovir and valine. This conversion is catalyzed by liver enzyme – valacyclovir hydrolase. After a single dose of 250-2000 mg of valacyclovir, the average Cmax of acyclovir in plasma in healthy volunteers with normal renal function is on average 10-37 µmol/L (2.2-8.3 µg/ml) and the average Tmax is 1-2 hours.

The bioavailability of acyclovir is 54% when valacyclovir is taken at a dose of 1000 mg or more and is independent of food intake. Cmax of valacyclovir in plasma is only 4% of the concentration of acyclovir, Tmax on average is 30-100 minutes after taking the drug; after 3 hours the Cmax level remains the same or decreases. Valacyclovir and acyclovir have similar pharmacokinetic parameters after oral administration.

Distribution. Protein binding of valacyclovir is 13-18%, acyclovir is 9-33%. Acyclovir is well distributed in tissues and body fluids, including brain, kidney, lung, liver, aqueous humor, tear fluid, intestine, muscle, spleen, uterus, mucous membrane and vaginal secretion, semen, amniotic fluid, cerebrospinal fluid (50% of concentration in plasma), herpes vesicle fluid. The highest concentrations are produced in the kidneys, liver, and intestine. It penetrates through the placenta and into the breast milk.

Evacuation. Valacyclovir is excreted with the urine, mainly as acyclovir (more than 30% of the dose) and its metabolite 9-carboxymethoxymethylguanine; less than 1% of the drug is excreted unchanged. T1/2 of valacyclovir is less than 30 minutes, of acyclovir – 2.5-3.3 hours. In elderly patients (65-83 years old) T1/2 of acyclovir is 3.3-3.7 hours, and in patients with terminal renal failure – about 14 hours.

The pharmacokinetics of valacyclovir and acyclovir are not significantly impaired in patients infected with HPV and VZV.

In HIV-infected patients, the pharmacokinetic parameters of acyclovir after oral administration of valacyclovir at doses of 1000 and 2000 mg are comparable to those observed in healthy volunteers.

In organ transplant recipients receiving valacyclovir at a dose of 2000 mg 4 times daily, the Cmax of acyclovir was equal to or greater than that of healthy volunteers receiving the same dose of the drug, and the daily AUC values were significantly higher.

In late pregnancy, the sustained daily AUC after receiving 1000 mg of valacyclovir was approximately 2 times greater than that of acyclovir at a dose of 1200 mg/day.

Indications

Adults:

Adults and children 12 years of age and older: Prevention of cytomegalovirus (CMV) infection as well as acute graft rejection reactions (in patients with kidney transplants), opportunistic infections and other herpesvirus infections (HPV, VZV) after organ transplants.

Active ingredient

Composition

1 film-coated tablet contains:

the active ingredient:

valacyclovir hydrochloride – 556.00 mg (in terms of valacyclovir 500.00 mg);

auxiliary substances:

Microcrystalline cellulose – 95.00 mg,

Hyprolose (hydroxypropyl cellulose) – 14.00 mg,

crospovidone – 28.00 mg,

magnesium stearate – 7.00 mg;

coating film:

Hypromellose – 10.5 mg;

Hyprolose (hydroxypropyl cellulose) – 4.07 mg;

talk – 4.12 mg;

titanium dioxide – 2.31 mg or white film coating dry mixture (hypromellose – 50%, hydroxypropyl cellulose – 19.4%, talc – 19.6%, titanium dioxide – 11%) – 21 mg.

How to take, the dosage

Treatment of shingles (Herpes zoster)
Adults:
The recommended dose is 1000 mg 3 times daily for 7 days.

Treatment of infections caused by HPV

Adults:
The recommended dose for episode therapy is 500 mg twice daily for 5 days.
In more severe cases of onset, treatment should be started as early as possible, and its duration may be extended from 5 to 10 days. In cases of relapses, treatment should be continued for 3 or 5 days. In relapsed HPV cases, it is ideal to prescribe valacyclovir in the prodromal period or immediately after the onset of the first symptoms of the disease.

As an alternative treatment for labial herpes, a twice-daily dose of valacyclovir is effective. The second dose should be taken approximately 12 hours (but not earlier than 6 hours) after the first dose. With this dosing regimen, the duration of treatment is 1 day. Therapy should be started when the earliest symptoms of labial herpes (i.e., tingling, itching, burning) appear.

Prevention (suppression) of recurrent infections caused by HPV

Adults:
In patients with preserved immunity, the recommended dose is 500 mg once daily.
In immunocompromised patients, the recommended dose is 500 mg twice daily.

Prevention of transmission of genital herpes to a healthy partner
In immunocompetent patients with relapses no more than 9 times per year, the recommended dose of valacyclovir is 500 mg once daily for one year or more each day.
There are no data on prevention of infection in other patient populations.

Prevention of cytomegalovirus (CMV) infection after transplantation

Adults and adolescents ages 12 years and older:
The recommended dose is 2 g 4 times daily, administered as soon as possible after transplantation.
The dose should be reduced depending on creatinine clearance.
The duration of treatment is 90 days, but in high-risk patients the course of treatment may be extended.

Interaction

Cimetidine and tubule secretion blockers reduce the effect (reduce the rate, but not the completeness of conversion to acyclovir). Dosage regimen adjustment is not required in persons with normal creatinine clearance.

Nephrotoxic drugs increase the risk of renal dysfunction. Caution should be exercised (monitoring for changes in renal function) when combining Valcicon at higher doses (4 g daily or more) with drugs that affect other renal functions (e.g.: cyclosporine, tacrolimus).

Acyclovir is excreted by the kidneys, mostly unchanged, through active renal secretion. Concomitant use of drugs with this excretion mechanism may lead to increased plasma concentrations of acyclovir.

After administration of Valcicon at a dose of 1000 mg, cimetidine and probenecid, which are excreted by the same route as Valacyclovir, increase the AUC of acyclovir and thus decrease its renal clearance. Because of the broad therapeutic index of acyclovir, no dose adjustment of Valcyclovir is necessary in this case.

Caution should be exercised if higher doses of valacyclovir (4 g per day or more) and drugs that compete with acyclovir for the elimination pathway are used concomitantly, since there is a potential risk of elevated plasma levels of one or both drugs or their metabolites.

The AUC of acyclovir and the inactive metabolite of mycophenolate mofetil have been observed to increase with concomitant use of these drugs.
Pharmacokinetics of valacyclovir does not change with concomitant use of digoxin, aluminum/magnesium-containing antacids, thiazide diuretics.

Special Instructions

In patients at risk of dehydration, especially in elderly patients, adequate fluid replenishment should be provided during treatment.

As acyclovir is excreted by the kidneys, the dose of Valcicon should be adjusted according to the degree of renal impairment. Patients with renal impairment have an increased risk of developing neurological complications; these patients should be closely monitored. As a rule, these reactions are reversible and disappear after discontinuation of the drug.

In patients with chronic renal failure (CKD), creatinine clearance should be measured frequently, particularly during periods when renal function changes rapidly (such as immediately after transplantation or graft engraftment), and the valacyclovir dose should be adjusted according to creatinine clearance rates.

There are no data on the use of Valacyclovir in high doses (4 g or more per day) in patients with liver disease, so high doses of Valcyclon should be used with caution.

Valcyclovir suppressive therapy reduces the risk of genital herpes transmission, but it does not eliminate the risk of infection and does not lead to complete cure. Valcyclone therapy is recommended in combination with safe sex.

The use of the drug in high doses for a long time in conditions accompanied by severe immunodeficiency (bone marrow transplantation, clinically evident forms of HIV infection, kidney transplantation) has led to the development of thrombocytopenic purpura and hemolytic-uremic syndrome, up to and including death.

In case of side effects of the central nervous system (including agitation, hallucinations, confusion, delirium, convulsions and encephalopathy) the drug is stopped.

Influence on driving and mechanisms
There are no data on the effect of valacyclovir used in therapeutic doses on the ability to drive vehicles and mechanisms. However, when assessing the patient’s ability to drive or operate moving mechanisms, it is necessary to take into account that side effects on the central nervous system may occur, so caution should be exercised.

Contraindications

With caution: hepatic/renal insufficiency; elderly; hypohydration; simultaneous use of nephrotoxic drugs; pregnancy; lactation; clinically expressed forms of HIV infection.

Side effects

Central nervous system disorders:headache, dizziness, psychotic symptoms, agitation, diminished mental capacity, ataxia, coma, confusion or depression of consciousness, dysarthria, encephalopathy, mania, hallucinations, convulsions, tremors.

The above reactions are reversible and are usually seen in patients with impaired renal function or with other predisposing conditions. In patients with an organ transplant who receive valacyclovir at high doses (8 g/day) for prevention of cytomegalovirus infection, neurological reactions develop more frequently than when taken at lower doses.

Respiratory system: dyspnea.

From the digestivesystem:Nausea, abdominal discomfort, vomiting, diarrhea, reversible abnormalities of functional liver tests (increased activity of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase), which are sometimes considered as manifestations of hepatitis.

Hematopoietic system disorders:leukopenia (mainly observed in patients with reduced immunity), thrombocytopenia, anemia, thrombotic thrombocytopenic purpura.
Skin disorders: erythema multiforme, rash, photosensitization, alopecia.

Allergic reactions: itching, urticaria, angioedema, anaphylaxis.
Urinary system disorders: pain in the renal projection, renal function disorders, including acute renal failure, renal colic. Renal colic may be associated with renal dysfunction.

Sensory organs: visual impairment.

Laboratory findings: decreased hemoglobin, hypercreatininemia.

Others:dysmenorrhea, nasopharyngitis, respiratory tract infections, increased blood pressure, tachycardia, fatigue; in patients with severe immune disorders, especially in adult patients with advanced HIV infection receiving high-dose valacyclovir
(8 g/day daily) for long periods of time, cases of renal failure, microangiopathic hemolytic anemia, and thrombocytopenia (sometimes in combination) have been observed. Similar adverse reactions have been noted in patients with the same disease but not receiving valacyclovir.

Overdose

Symptoms: In overdose of valacyclovir acute renal failure may occur and neurological symptoms, including confusion, hallucinations, agitation, depression of consciousness and coma, nausea and vomiting are also noted. Caution should be exercised when using the drug to prevent overdose.

Many cases of overdose have been associated with the use of the drug to treat patients with impaired renal function and elderly patients due to non-compliance with dosing regimens (who repeatedly received doses of valacyclovir greater than recommended).

Treatment.

Pregnancy use

There are limited data on the use of valacyclovir in pregnancy.

Valacyclovir is used only when the potential benefit to the mother outweighs the possible risk to the fetus.Recorded pregnancy outcomes in women who took valacyclovir or acyclovir (the active metabolite of valacyclovir) showed no increase in birth defects in their babies compared to the general population.

Because the registry included a small number of women who took valacyclovir in pregnancy, no reliable and definitive conclusions about the safety of valacyclovir in pregnancy can be drawn.

Acyclovir, the main metabolite of valacyclovir, is excreted with breast milk. After oral administration of valacyclovir at a dose of 500 mg, the Cmax of acyclovir in breast milk was 0.5-2.3 times
(1.4 times on average) higher than the corresponding concentrations of acyclovir in maternal plasma.

The mean concentration of acyclovir in breast milk was 2.24 μg/mL (9.95 μmol/L). If the mother took valacyclovir orally at a dose of 500 mg 2 times/day, the baby would have the same exposure to acyclovir as if she took acyclovir orally at a dose of about 0.61 mg/kg/day.

Similarities