Favirox, 250 mg 21 pcs

Interaction

Simultaneous use with probenecid may increase the concentration of penciclovir in blood plasma. To prevent the development of toxic reactions, patients receiving Favirox at a dose of 500 mg concomitantly with probenecid should be monitored, considering the possibility of reducing the dose of famiclovir.

There have been no clinically significant changes in pharmacokinetic parameters of penciclovir when administered as a single dose (500 mg) immediately after administration of antacids (magnesium and aluminum hydroxide) or in patients who received prior therapy with allopurinol cimetidine theophylline zidovudine promethazine (multiple administration).

The single administration of famcyclovir (500 mg dose) together with emtricitabine or zidovudine showed no changes in pharmacokinetic parameters of penciclovir zidovudine metabolite zidovudine (zidovudine glucuronide) and emtricitabine.

There were no changes in the pharmacokinetic parameters of penciclovir and digoxin when using famiclovir (at a dose of 500 mg 3 times daily) together with digoxia.

Please note that the conversion of the inactive metabolite 6-deoxypencyclovir (which is formed during deacetylation of famiclovir) to pencyclovir is catalyzed by the enzyme aldehydoxidase. There is a possibility of drug interaction when using Favirox together with agents metabolized with participation of this enzyme or which inhibit its activity.

When using famcyclovir in combination with cimetidine and promethazine, which are aldehydoxidase inhibitors, in vitro no impairment of penciclovir formation from famcyclovir was found. However, when taking famcyclovir together with a powerful aldehydoxidase inhibitor in vitro raloxifene there may be a violation of penciclovir formation from famcyclovir and as a consequence the effectiveness of famcyclovir. It is necessary to evaluate the clinical efficacy of antiviral therapy when used concomitantly with raloxifene.

With regard to the fact that famcyclovir is a weak inhibitor of aldehydroxidase in vitro it is possible that its effect on the pharmacokinetic parameters of drugs metabolized with the participation of this enzyme.

In experimental studies, famcyclovir had no inducing effect on the cytochrome P450 system and did not inhibit the CYP3A4 enzyme.

Directions for use

The drug should be taken orally, regardless of meals, without chewing, with water. Treatment with the drug should be started as soon as possible, immediately after the appearance of the first symptoms of the disease (tingling, itching and burning).

Infections caused by VZV (herpes zoster), including ophthalmoherpes in immunocompetent patients:

The recommended dose is 500 mg 3 times daily for 7 days.

Infection caused by VZV (herpes zoster) in immunocompromised patients:

The recommended dose is 500 mg 3 times daily for 10 days.

Infection caused by HSV (labial or genital herpes) in immunocompromised patients:

In a first episode of genital herpes, the recommended dose is 250 mg 3 times daily for 5 days;

In recurrent genital herpes, 1000 mg 2 times daily for 1 day or 125 mg 2 times daily for 5 days or 500 mg once, followed by 3 doses of 250 mg every 12 hours.

In relapses of labial herpes, 1500 mg once daily for 1 day or 750 mg twice daily for 1 day.

Infections caused by HSV (orolabial or genital herpes) in immunocompromised patients:

The recommended dose is 500 mg twice daily for 7 days.

To prevent exacerbations of genital herpes (suppressive therapy), 250 mg 2 times daily is used. The duration of therapy depends on the severity of the disease. Periodic evaluation of possible disease course changes after 12 months is recommended. In HIV-infected patients the effective dose is 500 mg 2 times a day.

Patients aged ≥65 years.

In elderly patients with normal renal function, correction of the dosing regimen of famcyclovir is not necessary.

Patients with impaired renal function.

In patients with impaired renal function there is a decrease in clearance of penciclovir. Recommendations for dosing regimen adjustment in immunocompetent patients with impaired renal function based on creatinine clearance are presented in Table 1.

Recommendations for dosing regimen adjustment in immunocompromised patients with impaired renal function as a function of creatinine clearance are presented in Table 2.

Table 1. Dosing regimen correction in immunocompromised patients with impaired renal function

Table 2. Dosing regimen correction in immunocompromised patients with impaired renal function

p> Patients with renal impairment who are on hemodialysis or receiving hemodialysis treatment.

Because penciclovir plasma concentrations decrease by 75% after a 4-hour hemodialysis procedure, famiclovir should be taken immediately after the hemodialysis procedure. See Tables 1 and 2 for a recommended dose adjustment regimen.

Patients with impaired liver function.

In patients with mild to moderate hepatic impairment, no dose adjustment is required. There is no experience of using the drug in patients with severe hepatic impairment.

Patients of the Negro race.

The efficacy of a 1-day, twice-daily dose of famcyclovir for the treatment of genital herpes recurrence in immunocompetent black patients was not greater than that of placebo. The clinical significance of drug dosing regimens for the treatment of both genital herpes relapses (within 2 or 5 days) and other infectious lesions caused by VZV and HSV is unknown.

Special Instructions

Treatment should begin as soon as the diagnosis is made.

Genital herpes is a sexually transmitted disease. During relapses, the risk of infection increases. If there are clinical signs of the disease, even if antiviral treatment is begun, patients should avoid sexual contact.

Impact on the ability to drive and/or operate motor vehicles

Introduction of Faviro is not expected. No effect of Favirox on driving and/or operating machinery is expected, but patients with dizziness, somnolence, mental confusion or other central nervous system disturbances during Favirox administration should refrain from driving and/or operating machinery during this period.

Synopsis

Filmed film-coated tablets, 250 mg:

Circular, biconvex, white film-coated tablets with a bevel and a rib on one side of the tablet.

Contraindications

Hypersensitivity to famcyclovir or any of the ingredients of the drug. Hypersensitivity to penciclovir.

Children under 18 years of age due to lack of data on efficacy and safety in patients in this age group.

Severe hepatic impairment due to lack of efficacy and safety data in this patient population.

Cautions:

Caution should be exercised when treating patients with impaired renal function for whom dosing adjustments may be necessary.

Special precautions are not required in elderly patients and patients with mild to moderate hepatic impairment.

Side effects

Clinical studies have shown good tolerability of famcyclovir, including in immunocompromised patients. Headache and nausea have been reported, but these were mild to moderate in frequency in patients receiving placebo. The remaining adverse events (AEs) have been identified in clinical practice during the post-registration period.

The NIs reported in clinical studies in immunocompromised patients were consistent with those reported in patients with normal immunity.

The World Health Organization (WHO) criteria were used to assess the incidence of adverse reactions: Very common (> 1/10); common (> 1/100, < 1/10); infrequent (> 1/1000, < 1/100); rare (> 1/10000, < 1/1000); very rare (< 1/10000), frequency unknown.

Blood and lymphatic system disorders: rare – thrombocytopenia;

Mental disorders: infrequent – confusion of consciousness (mostly in elderly patients); rare – hallucinations;

Nervous system disorders: very common – headache, frequent – dizziness, infrequent – somnolence (mostly in elderly patients), frequency unknown – seizures*;

Heart disorders: rare – feeling of “heart palpitations”;

Gastrointestinal disorders: frequent – nausea, vomiting, abdominal pain, diarrhea;

Liver and biliary tract disorders: rare – cholestatic jaundice;

Immune system disorders: frequency unknown – anaphylactic shock*, anaphylactic reaction*;

Skin and subcutaneous tissue disorders: frequent – rash, itching; infrequent – angioedema (swelling of the face, eyelids, periorbital area, throat), urticaria; frequency unknown – severe skin reactions* (incl.erythema multiforme, Stephen-Johnson syndrome, Lyell syndrome (toxic epidermal necrolysis), allergic vasculitis).

Laboratory and instrumental data: often liver function abnormalities

* – NSCs not observed in clinical trials, identified in post-marketing observations, as well as those described in the literature. Because this information was obtained through spontaneous reporting, and because the exact number of patients who received the drug has not been determined, the frequency of these reactions cannot be estimated; therefore, the frequency of these reactions is stated as “unknown.

Overdose

There are limited data on famcyclovir overdose.

There have been described cases of famcyclovir overdose (10.5 g) without clinical manifestations.

Treatment: symptomatic and supportive. If the recommendations on dose reduction of famcyclovir were not followed with regard to renal function, acute renal failure has rarely been observed in patients with renal disease. Penciclovir, which is the active metabolite of famcyclovir, is excreted by hemodialysis. Plasma concentrations of penciclovir decrease by 75% after hemodialysis for 4 hours.

Pregnancy use

No embryotoxic and teratogenic effects of famcyclovir and penciclovir were found in animal studies. In studies of oral administration of famcyclovir, penciclovir was excreted with milk of lactating rats. It is unknown whether pencyclovir is excreted with breast milk in humans.

However, since there are not enough data on the safety of using penciclovir in pregnant and breastfeeding women, its use during pregnancy and breastfeeding is possible only if the benefit of therapy for the mother outweighs the potential risk to the fetus and child.

There are no data requiring special recommendations for patients with preserved reproductive potential.

Famcyclovir has no pronounced effect on the spermogram morphology or motility of human sperm. Decreased fertility was noted in an experimental model in male rats treated with famcyclovir at a dose of 500 mg/kg body weight in female rats no significant reduction in fertility was noted.