Famciclovir

1 INDICATIONS & USAGE Famciclovir tablet, 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 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

2 DOSAGE & ADMINISTRATION Famciclovir tablets may be taken with or without food. Immunocompetent Adult Patients ( 2.1 ) Herpes labialis (cold sores) 1500 mg as a single dose Genital herpes Treatment of recurrent episodes Suppressive therapy Herpes Zoster (shingles) 1000 mg twice daily for 1 day 250 mg twice daily 500 mg every 8 hours for 7 days HIV-Infected Adult Patients ( 2.2 ) Recurrent episodes of orolabial or genital herpes 500 mg twice daily for 7 days Patients with renal impairment: Adjust dose based on creatinine clearance. ( 2.3 ) 2.1 Dosing Recommendation in Immunocompetent Adult Patients Herpes labialis (cold sores): The recommended dosage of famciclovir tablets for the treatment of recurrent herpes labialis is 1500 mg as a single dose. Therapy should be initiated at the first sign or symptom of herpes labialis (e.g., tingling, itching, burning, pain, or lesion). Genital herpes: Recurrent episodes: The recommended dosage of famciclovir tablets for the treatment of recurrent episodes of genital herpes is 1000 mg twice daily for 1 day. Therapy should be initiated at the first sign or symptom of a recurrent episode (e.g., tingling, itching, burning, pain, or lesion). Suppressive therapy: The recommended dosage of famciclovir tablets for chronic suppressive therapy of recurrent episodes of genital herpes is 250 mg twice daily. Herpes zoster (shingles): The recommended dosage of famciclovir tablets for the treatment of herpes zoster is 500 mg every 8 hours for 7 days. Therapy should be initiated as soon as herpes zoster is diagnosed. 2.2 Dosing Recommendation in HIV-Infected Adult Patients Recurrent orolabial or genital herpes: The recommended dosage of famciclovir tablets for the treatment of recurrent orolabial or genital herpes in HIV-infected patients is 500 mg twice daily for 7 days. Therapy should be initiated at the first sign or symptom of a recurrent episode (e.g., tingling, itching, burning, pain, or lesion). 2.3 Dosing Recommendation in Patients with Renal Impairment Dosage recommendations for adult patients with renal impairment are provided in Table 1 [see Use in Specific Populations ( 8.6 ), Clinical Pharmacology ( 12.3 )]. Table 1: Dosage Recommendations for Adult Patients with Renal Impairment Indication and Normal Dosage Regimen Creatinine Clearance (mL/min) Adjusted Dosage Regimen Dose (mg) Dosing Interval Single-Day Dosing Regimens Recurrent Genital Herpes 1000 mg every 12 hours for1 day ≥60 1000 every 12 hours for 1 day 40-59 500 every 12 hours for 1 day 20-39 500 single dose <20 250 single dose HD* 250 single dose following dialysis Recurrent Herpes Labialis 1500 mg single dose ≥60 1500 single dose 40-59 750 single dose 20-39 500 single dose <20 250 single dose HD* 250 single dose following dialysis Multiple-Day Dosing Regimens Herpes Zoster 500 mg every 8 hours ≥60 500 every 8 hours 40-59 500 every 12 hours 20-39 500 every 24 hours <20 250 every 24 hours HD* 250 following each dialysis Suppression of Recurrent Genital Herpes 250 mg every 12 hours ≥40 250 every 12 hours 20-39 125 every 12 hours <20 125 every 24 hours HD* 125 following each dialysis Recurrent Orolabial or Genital Herpes in HIV-Infected Patients 500 mg every 12 hours ≥40 500 every 12 hours 20-39 500 every 24 hours <20 250 every 24 hours HD* 250 following each dialysis *Hemodialysis

6 ADVERSE REACTIONS 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 Hetero Labs Limited at 1-866-495-1995 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* Incidence Events Herpes Zoster † Recurrent Genital Herpes ‡ Genital Herpes- Suppression § 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 * Patients may have entered into more than one clinical trial. † 7 days of treatment ‡ 1 day of treatment § daily treatment Table 3 lists selected laboratory abnormalities in genital herpes suppression trials. Table 3: Selected Laboratory Abnormalities in Genital Herpes Suppression Studies * Parameter Famciclovir (n = 660) † % 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 * Percentage of patients with laboratory abnormalities that were increased or decreased from baseline and were outside of specified ranges. † n values represent the minimum number of patients assessed for each laboratory parameter. 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. 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

12.3 Pharmacokinetics Famciclovir is the diacetyl 6-deoxy analog of the active antiviral compound penciclovir. Following oral administration famciclovir undergoes rapid and extensive metabolism to penciclovir and little or no famciclovir is detected in plasma or urine. Penciclovir is predominantly eliminated unchanged by the kidney. Therefore, the dose of famciclovir needs to be adjusted in patients with different degrees of renal impairment [see Dosage and Administration ( 2.3 )]. Pharmacokinetics in adults: Absorption and Bioavailability: The absolute bioavailability of penciclovir is 77 ± 8% as determined following the administration of a 500 mg famciclovir oral dose and a 400 mg penciclovir intravenous dose to 12 healthy male subjects. Penciclovir concentrations increased in proportion to dose over a famciclovir dose range of 125 mg to 1000 mg administered as a single dose. Table 5 shows the mean pharmacokinetic parameters of penciclovir after single administration of famciclovir to healthy male volunteers. Table 5: Mean Pharmacokinetic Parameters of Penciclovir in Healthy Adult Subjects* Dose AUC (0-inf) † (mcg hr/mL) C max ‡ (mcg/mL) t max § (h) 125 mg 2.24 0.8 0.9 250 mg 4.48 1.6 0.9 500 mg 8.95 3.3 0.9 1000 mg 17.9 6.6 0.9 * Based on pharmacokinetic data from 17 studies † AUC (0-inf) (mcg hr/mL) =area under the plasma concentration-time profile extrapolated to infinity. ‡ C max (mcg/mL) = maximum observed plasma concentration. § t max (h) = time to C max . Following oral single-dose administration of 500 mg famciclovir to 7 patients with herpes zoster, the AUC (mean ± SD), C max , and t max were 12.1±1.7 mcg hr/mL, 4.0±0.7 mcg/mL, and 0.7±0.2 hours, respectively. The AUC of penciclovir was approximately 35% greater in patients with herpes zoster as compared to healthy volunteers. Some of this difference may be due to differences in renal function between the 2 groups. There is no accumulation of penciclovir after the administration of 500 mg famciclovir three times daily for 7 days. Penciclovir C max decreased approximately 50% and t max was delayed by 1.5 hours when a capsule formulation of famciclovir was administered with food (nutritional content was approximately 910 Kcal and 26% fat). There was no effect on the extent of availability (AUC) of penciclovir. There was an 18% decrease in C max and a delay in t max of about 1 hour when famciclovir was given 2 hours after a meal as compared to its administration 2 hours before a meal. Because there was no effect on the extent of systemic availability of penciclovir, famciclovir can be taken without regard to meals. Distribution : The volume of distribution (Vdβ) was 1.08 ± 0.17 L/kg in 12 healthy male subjects following a single intravenous dose of penciclovir at 400 mg administered as a 1-hour intravenous infusion. Penciclovir is less than 20% bound to plasma proteins over the concentration range of 0.1 to 20 mcg/mL. The blood/plasma ratio of penciclovir is approximately 1. Metabolism : Following oral administration, famciclovir is deacetylated and oxidized to form penciclovir. Metabolites that are inactive include 6-deoxy penciclovir, monoacetylated penciclovir, and 6-deoxy monoacetylated penciclovir (5%, less than 0.5% and less than 0.5% of the dose in the urine, respectively). Little or no famciclovir is detected in plasma or urine. An in vitro study using human liver microsomes demonstrated that cytochrome P450 does not play an important role in famciclovir metabolism. The conversion of 6-deoxy penciclovir to penciclovir is catalyzed by aldehyde oxidase. Cimetidine and promethazine, in vitro inhibitors of aldehyde oxidase, did not show relevant effects on the formation of penciclovir in vivo [see Drug Interactions ( 7.2 )]. Elimination : Approximately 94% of administered radioactivity was recovered in urine over 24 hours (83% of the dose was excreted in the first 6 hours) after the administration of 5 mg/kg radiolabeled penciclovir as a 1-hour infusion to 3 healthy male volunteers. Penciclovir accounted for 91% of the radioactivity excreted in the urine. Following the oral administration of a single 500 mg dose of radiolabeled famciclovir to 3 healthy male volunteers, 73% and 27% of administered radioactivity were recovered in urine and feces over 72 hours, respectively. Penciclovir accounted for 82% and 6-deoxy penciclovir accounted for 7% of the radioactivity excreted in the urine. Approximately 60% of the administered radiolabeled dose was collected in urine in the first 6 hours. After intravenous administration of penciclovir in 48 healthy male volunteers, mean ± SD total plasma clearance of penciclovir was 36.6 ± 6.3 L/hr (0.48 ± 0.09 L/hr/kg). Penciclovir renal clearance accounted for 74.5 ± 8.8% of total plasma clearance. Renal clearance of penciclovir following the oral administration of a single 500 mg dose of famciclovir to 109 healthy male volunteers was 27.7 ± 7.6 L/hr. Active tubular secretion contributes to the renal elimination of penciclovir. The plasma elimination half-life of penciclovir was 2.0 ± 0.3 hours after intravenous administration of penciclovir to 48 healthy male volunteers and 2.3 ± 0.4 hours after oral administration of 500 mg famciclovir to 124 healthy male volunteers. The half-life in 17 patients with herpes zoster was 2.8±1.0 hours and 2.7±1.0 hours after single and repeated doses, respectively. Special populations: Geriatric patients: Based on cross study comparison, penciclovir AUC was 40% higher and penciclovir renal clearance was 22% lower in elderly subjects (n=18, age 65 to 79 years) as compared with younger subjects. Some of this difference may be due to differences in renal function between the 2 groups. No famciclovir dosage adjustment based on age is recommended unless renal function is impaired [see Dosage and Administration ( 2.3 ), Use in Specific Populations ( 8.5 )]. Patients with renal impairment: In subjects with varying degrees of renal impairment, apparent plasma clearance, renal clearance, and the plasma-elimination rate constant of penciclovir decreased linearly with reductions in renal function, after both single and repeated dosing [see Use in Specific Populations ( 8.6 )] . A dosage adjustment is recommended for patients with renal impairment [see Dosage and Administration ( 2.3 )]. Patients with hepatic impairment : Mild or moderate hepatic impairment had no effect on the extent of availability (AUC) of penciclovir [see Use in Specific Populations ( 8.7 )]. No dosage adjustment is recommended for patients with mild or moderate hepatic impairment. The effect of severe hepatic impairment on the pharmacokinetics of penciclovir has not been evaluated. HIV-infected patients: Following oral administration of a single dose of 500 mg famciclovir to HIV-positive patients, the pharmacokinetic parameters of penciclovir were comparable to those observed in healthy subjects. Gender: The pharmacokinetics of penciclovir were evaluated in 18 healthy male and 18 healthy female volunteers after single-dose oral administration of 500 mg famciclovir. AUC of penciclovir was 9.3±1.9 mcg hr/mL and 11.1±2.1 mcg hr/mL in males and females, respectively. Penciclovir renal clearance was 28.5±8.9 L/hr and 21.8±4.3 L/hr, respectively. These differences were attributed to differences in renal function between the 2 groups. No famciclovir dosage adjustment based on gender is recommended. Race: A retrospective evaluation was performed to compare the pharmacokinetic parameters obtained in black and Caucasian subjects after single and repeat once-daily, twice-daily, or three times-daily administration of famciclovir 500 mg. Data from a study in healthy volunteers (single dose), a study in subjects with varying degrees of renal impairment (single and repeat dose) and a study in subjects with hepatic impairment (single dose) did not indicate any significant differences in the pharmacokinetics of penciclovir between black and Caucasian subjects.