Famciclovir

Famciclovir, a prodrug of penciclovir, is a deoxynucleoside analog DNA polymerase inhibitor indicated for: Immunocompetent Adult Patients ( 1.1 )

• Herpes labialis (cold sores) o Treatment of recurrent episodes
• Genital herpes o Treatment of recurrent episodes o Suppressive therapy of recurrent episodes
• Herpes zoster (shingles) Human Immunodeficiency Virus (HIV) -Infected Adult Patients ( 1.2 )
• Treatment of recurrent episodes of orolabial or genital herpes Limitation of Use The efficacy and safety of famciclovir tablets have not been established for:
• Patients with first episode of genital herpes
• Patients with ophthalmic zoster
• Immunocompromised patients other than for the treatment of recurrent episodes of orolabial or genital herpes in HIV- infected patients
• Black and African American patients with recurrent genital herpes

1.1 Immunocompetent Adult Patients Herpes labialis(cold sores): Famciclovir tablets are indicated for the treatment of recurrent herpes labialis in adult patients. Genital herpes: Recurrent episodes: Famciclovir tablets are indicated for the treatment of recurrent episodes of genital herpes. The efficacy of famciclovir tablets when initiated more than 6 hours after onset of symptoms or lesions has not been established. Suppressive therapy: Famciclovir tablets are indicated for chronic suppressive therapy of recurrent episodes of genital herpes in adult patients. The efficacy and safety of famciclovir tablets for the suppression of recurrent genital herpes beyond 1 year have not been established. Herpes zoster (shingles): Famciclovir tablets are indicated for the treatment of herpes zoster in adult patients. The efficacy of famciclovir tablets when initiated more than 72 hours after onset of rash has not been established. 1.2 HIV-Infected Adult Patients Recurrent orolabial or genital herpes: Famciclovir tablets are is indicated for the treatment of recurrent episodes of orolabial or genital herpes in HIV-infected adults. The efficacy of famciclovir tablets when initiated more than 48 hours after onset of symptoms or lesions has not been established. Limitation of Use The efficacy and safety of famciclovir tablets have not been established for:

• Patients with first episode of genital herpes
• Patients with ophthalmic zoster
• Immunocompromised patients other than for the treatment of recurrent orolabial or genital herpes in HIV-infected patients
• Black and African American patients with recurrent genital herpes

Famciclovir tablets, USP are available in 3 strengths:

• 125 mg: White to off white, round, film-coated, biconvex, engraved with "ML 67" on one side and plain on the other side.
• 250 mg: White to off white, round, film-coated, biconvex, engraved with "ML 70" on one side and plain on the other side.
• 500 mg: White to off white, oval, film-coated, biconvex, engraved with "ML 72" on one side and plain on the other side. Tablets : 125 mg, 250 mg, 500 mg ( 3 )

Famciclovir tablets are contraindicated in patients with known hypersensitivity to the product, its components, or Denavir ® (penciclovir cream). Known hypersensitivity to the product, its components, or Denavir ® (penciclovir cream) ( 4 )

Acute renal failure: May occur in patients with underlying renal disease who receive higher than recommended doses of famciclovir for their level of renal function. Reduce dosage in patients with renal impairment ( 2.3, 8.6 )

5.1 Acute Renal Failure Cases of acute renal failure have been reported in patients with underlying renal disease who have received inappropriately high doses of famciclovir for their level of renal function. Dosage reduction is recommended when administering famciclovir tablets to patients with renal impairment [see Dosage and Administration ( 2.3 ), Use in Specific Populations ( 8.6 )].

Acute renal failure is discussed in greater detail in other sections of the label [see Warnings and Precautions ( 5 )]. The most common adverse events reported in at least 1 indication by greater than 10% of adult patients treated with famciclovir are headache and nausea. The most common adverse events reported in at least 1 indication by greater than 10% of adult patients are headache and nausea. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Macleods Pharma USA, Inc. at 1-888-943-3210 or 1-855-926-3384 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch

6.1 Clinical Trials Experience in Adult Patients Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in practice. Immunocompetent patients: The safety of famciclovir has been evaluated in active- and placebo-controlled clinical studies involving 816 famciclovir treated patients with herpes zoster (famciclovir , 250 mg three times daily to 750 mg three times daily); 163 famciclovir treated patients with recurrent genital herpes ( famciclovir, 1000 mg twice daily); 1,197 patients with recurrent genital herpes treated with famciclovir as suppressive therapy (125 mg once daily to 250 mg three times daily) of which 570 patients received famciclovir (open-labeled and/or double-blind) for at least 10 months; and 447 famciclovir treated patients with herpes labialis ( famciclovir, 1500 mg once daily or 750 mg twice daily). Table 2 lists selected adverse events. Table 2: Selected Adverse Events (all grades and without regard to causality) Reported by Greater Than or Equal to 2% of Patients in Placebo-Controlled Famciclovir Trials Patients may have entered into more than one clinical trial Incidence Events Herpes Zoster 7 days of treatment Recurrent Genital Herpes 1 day of treatment Genital Herpes- Suppression daily treatment Herpes Labialis Famciclovir (n=273) % Placebo (n=146) % Famciclovir (n=163) % Placebo (n=166) % Famciclovir (n=458) % Placebo (n=63) % Famciclovir (n=447) % Placebo (n=254) % Nervous System Headache 22.7 17.8 13.5 5.4 39.3 42.9 8.5

6.7 Paresthesia 2.6 0.0 0.0 0.0 0.9 0.0 0.0

0.0 Migraine 0.7 0.7 0.6 0.6 3.1 0.0 0.2

0.0 Gastrointestinal Nausea 12.5 11.6 2.5 3.6 7.2 9.5 2.2

3.9 Diarrhea 7.7 4.8 4.9 1.2 9.0 9.5 1.6

0.8 Vomiting 4.8 3.4 1.2 0.6 3.1 1.6 0.7

0.0 Flatulence 1.5 0.7 0.6 0.0 4.8 1.6 0.2

0.0 Abdominal Pain 1.1 3.4 0.0 1.2 7.9 7.9 0.2

0.4 Body as a Whole Fatigue 4.4 3.4 0.6 0.0 4.8 3.2 1.6

0.4 Skin and Appendages Pruritus 3.7 2.7 0.0 0.6 2.2 0.0 0.0

0.0 Rash 0.4 0.7 0.0 0.0 3.3 1.6 0.0

0.0 Reproductive Female Dysmenorrhea 0.0 0.7 1.8 0.6 7.6 6.3 0.4

0.0 Table 3: selected laboratory abnormalities in genital herpes suppression trials Table 3 Selected Laboratory Abnormalities in Genital Herpes Suppression Studies Percentage of patients with laboratory abnormalities that were increased or decreased from baseline and were outside of specified ranges. Parameter Famciclovir (n = 660) n values represent the minimum number of patients assessed for each laboratory parameter. % Placebo (n = 210) % Anemia (<0.8 x NRL) 0.1

0.0 Leukopenia (<0.75 x NRL) 1.3

0.9 Neutropenia (<0.8 x NRL) 3.2 1.5 AST (SGOT) (>2 x NRH) 2.3 1.2 ALT (SGPT) (>2 x NRH) 3.2

1.5 Total Bilirubin (>1.5 x NRH) 1.9

1.2 Serum Creatinine (>1.5 x NRH) 0.2

0.3 Amylase (>1.5 x NRH) 1.5

1.9 Lipase (>1.5 x NRH) 4.9 4.7 NRH = Normal Range High. NRL = Normal Range Low. HIV-infected patients: In HIV-infected patients, the most frequently reported adverse events for famciclovir (500 mg twice daily; n=150) and acyclovir (400 mg, 5x/day; n=143), respectively, were headache (17% vs. 15%), nausea (11% vs. 13%), diarrhea (7% vs. 11%), vomiting (5% vs. 4%), fatigue (4% vs. 2%), and abdominal pain (3% vs. 6%).

6.2 Postmarketing Experience The adverse events listed below have been reported during post-approval use of famciclovir tablets. Because these events are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure: Blood and lymphatic system disorders: Thrombocytopenia Hepatobiliary disorders: Abnormal liver function tests, cholestatic jaundice Immune system disorders : Anaphylactic shock, anaphylactic reaction Nervous system disorders: Dizziness, somnolence, seizure Psychiatric disorders: Confusion (including delirium, disorientation, and confusional state occurring predominantly in the elderly), hallucinations Skin and subcutaneous tissue disorders: Urticaria, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, angioedema (e.g., face, eyelid, periorbital, and pharyngeal edema), hypersensitivity vasculitis Cardiac disorders: Palpitations

Probenecid: May increase penciclovir levels. Monitor for evidence of penciclovir toxicity ( 7.2 )

7.1 Potential for Famciclovir to Affect Other Drugs The steady-state pharmacokinetics of digoxin were not altered by concomitant administration of multiple doses of famciclovir (500 mg three times daily). No clinically significant effect on the pharmacokinetics of zidovudine, its metabolite zidovudine glucuronide, or emtricitabine was observed following a single oral dose of 500 mg famciclovir coadministered with zidovudine or emtricitabine. An in vitro study using human liver microsomes suggests that famciclovir is not an inhibitor of CYP3A4 enzymes.

7.2 Potential for Other Drugs to Affect Penciclovir No clinically significant alterations in penciclovir pharmacokinetics were observed following single-dose administration of 500 mg famciclovir after pretreatment with multiple doses of allopurinol, cimetidine, theophylline, zidovudine, promethazine, when given shortly after an antacid (magnesium and aluminum hydroxide), or concomitantly with emtricitabine. No clinically significant effect on penciclovir pharmacokinetics was observed following multiple-dose (three times daily) administration of famciclovir (500 mg) with multiple doses of digoxin. Concurrent use with probenecid or other drugs significantly eliminated by active renal tubular secretion may result in increased plasma concentrations of penciclovir. The conversion of 6-deoxy penciclovir to penciclovir is catalyzed by aldehyde oxidase. Interactions with other drugs metabolized by this enzyme and/or inhibiting this enzyme could potentially occur. Clinical interaction studies of famciclovir with cimetidine and promethazine, in vitro inhibitors of aldehyde oxidase, did not show relevant effects on the formation of penciclovir. Raloxifene, a potent aldehyde oxidase inhibitor in vitro, could decrease the formation of penciclovir. However, a clinical drug-drug interaction study to determine the magnitude of interaction between penciclovir and raloxifene has not been conducted.

8.1 Pregnancy Risk Summary Available data from pharmacovigilance reports with famciclovir use in pregnant women have not identified a drug-associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes. There are risks to the fetus associated with untreated herpes simplex virus during pregnancy ( see Clinical Considerations ). After oral administration, famciclovir (prodrug) is converted to penciclovir (active drug). In animal reproduction studies with famciclovir, no evidence of adverse developmental outcomes was observed at systemic exposures of penciclovir (AUC) slightly higher than those at the maximum recommended human dose (MRHD) of famciclovir ( see Data ). The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15- 20%, respectively. Clinical Considerations Disease-associated maternal and/or embryo-fetal risk The risk of neonatal herpes infection varies from 30% to 50% for genital herpes simplex virus (HSV) infections that occur in late pregnancy (third trimester), whereas in early pregnancy, infection carries a risk of about 1%. A primary herpes outbreak during the first trimester of pregnancy has been associated with neonatal chorioretinitis, microcephaly and, in rare cases, skin lesions. In very rare cases, transplacental transmission can occur resulting in congenital infection, including microcephaly, hepatosplenomegaly, intrauterine growth restriction and stillbirth. Co-infection with HSV increases the risk of perinatal HIV transmission in women who had a clinical diagnosis of genital herpes during pregnancy. Data Animal Data Famciclovir was administered orally to pregnant rats and rabbits (up to 1000 mg/kg/day) on gestation Day(s) 6 to 15, and to rats on gestation Day 15 to lactation/post-partum Day 25. No adverse effects on embryo-fetal (rats and rabbits) or pre/post-natal (rats) development were observed up to the highest dose tested. During organogenesis, systemic exposures of penciclovir (active metabolite) were 3.4 times (rats) and 1.6 times (rabbits) the human systemic exposure of penciclovir based on AUC at the MRHD.

8.2 Lactation Risk Summary There are no data on the presence of famciclovir (prodrug) or penciclovir (active drug) in human milk, the effects on the breastfed infant, or the effects on milk production. Animal data indicate that penciclovir is present in the milk of lactating rats (see Data). The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for famciclovir and any potential adverse effects on the breastfed infant from famciclovir or from the underlying maternal condition. Data Penciclovir was the primary drug-related component excreted into the milk of lactating rats following a single oral dose of 40 mg per kg on lactation Day 12, with milk concentrations of up to approximately 8 times that of maternal plasma concentrations observed 0.5 hours postdose.

8.3 Females and Males of Reproductive Potential Infertility Decreased fertility, due to testicular toxicity, was observed in male animals following repeated administration of famciclovir or penciclovir [ see Nonclinical Toxicology ( 13.1 )]. In two placebo-controlled studies, 130 men with a history of recurrent genital herpes received either oral famciclovir (250 mg twice daily; n=66) or placebo (n=64) therapy for 18 weeks. The men were otherwise healthy and had a normal sperm profile prior to treatment. There was no evidence of significant effects on sperm count, motility or morphology during famciclovir treatment or during an 8-week follow-up.

8.4 Pediatric Use The efficacy of famciclovir tablets has not been established in pediatric patients. The pharmacokinetic profile and safety of famciclovir (experimental granules mixed with OraSweet ® or tablets) were studied in 3 open-label studies. Study 1 was a single-dose pharmacokinetic and safety study in infants 1 month to less than 1 year of age who had an active herpes simplex virus (HSV) infection or who were at risk for HSV infection. Eighteen subjects were enrolled and received a single dose of famciclovir experimental granules mixed with OraSweet based on the patient’s body weight (doses ranged from 25 mg to 175 mg). These doses were selected to provide penciclovir systemic exposures similar to the penciclovir systemic exposures observed in adults after administration of 500 mg famciclovir. The efficacy and safety of famciclovir have not been established as suppressive therapy in infants following neonatal HSV infections. In addition, the efficacy cannot be extrapolated from adults to infants because there is no similar disease in adults. Therefore, famciclovir is not recommended in infants. Study 2 was an open-label, single-dose pharmacokinetic, multiple-dose safety study of famciclovir experimental granules mixed with OraSweet in children 1 to less than 12 years of age with clinically suspected HSV or varicella zoster virus (VZV) infection. Fifty-one subjects were enrolled in the pharmacokinetic part of the study and received a single body weight adjusted dose of famciclovir (doses ranged from 125 mg to 500 mg). These doses were selected to provide penciclovir systemic exposures similar to the penciclovir systemic exposures observed in adults after administration of 500 mg famciclovir. Based on the pharmacokinetic data observed with these doses in children, a new weight-based dosing algorithm was designed and used in the multiple-dose safety part of the study. Pharmacokinetic data were not obtained with the revised weight-based dosing algorithm. A total of 100 patients were enrolled in the multiple-dose safety part of the study; 47 subjects with active or latent HSV infection and 53 subjects with chickenpox. Patients with active or latent HSV infection received famciclovir twice a day for 7 days. The daily dose of famciclovir ranged from 150 mg to 500 mg twice daily depending on the patient’s body weight. Patients with chickenpox received famciclovir three times daily for 7 days. The daily dose of famciclovir ranged from 150 mg to 500 mg three times daily depending on the patient’s body weight. The clinical adverse events and laboratory test abnormalities observed in this study were similar to these seen in adults. The available data are insufficient to support the use of famciclovir for the treatment of children 1 to less than 12 years of age with chickenpox or infections due to HSV for the following reasons: Chickenpox: The efficacy of famciclovir for the treatment of chickenpox has not been established in either pediatric or adult patients. Famciclovir is approved for the treatment of herpes zoster in adult patients. However, extrapolation of efficacy data from adults with herpes zoster to children with chickenpox would not be appropriate. Although chickenpox and herpes zoster are caused by the same virus, the diseases are different. Genital herpes: Clinical information on genital herpes in children is limited. Therefore, efficacy data from adults cannot be extrapolated to this population. Further, famciclovir has not been studied in children 1 to less than 12 years of age with recurrent genital herpes. None of the children in Study 2 had genital herpes. Herpes labialis: There are no pharmacokinetic and safety data in children 1 to less than 12 years of age to support a famciclovir dose that provides penciclovir systemic exposures comparable to the penciclovir systemic exposures in adults after a single dose administration of 1500 mg. Moreover, no efficacy data have been obtained in children 1 to less than 12 years of age with recurrent herpes labialis. […]

Famciclovir is an orally administered prodrug of the anti-alpha herpes viral agent penciclovir [ see Microbiology ( 12.4 )].