Interbi

Lamisil (terbinafine hydrochloride) Tablets are indicated for the treatment of onychomycosis of the toenail or fingernail due to dermatophytes (tinea unguium).

Prior to initiating treatment, appropriate nail specimens for laboratory testing [potassium hydroxide (KOH) preparation, fungal culture, or nail biopsy] should be obtained to confirm the diagnosis of onychomycosis.

Fingernail onychomycosis: One 250 mg tablet once daily for 6 weeks.

Toenail onychomycosis: One 250 mg tablet once daily for 12 weeks.

The optimal clinical effect is seen some months after mycological cure and cessation of treatment. This is related to the period required for outgrowth of healthy nail.

Lamisil (terbinafine hydrochloride) Oral Granules is contraindicated in individuals with a history of allergic reaction to oral terbinafine because of the risk of anaphylaxis.

WARNINGS

Included as part of the PRECAUTIONS section.

PRECAUTIONS

Hepatotoxicity

Cases of liver failure, some leading to death or liver transplant, have occurred with the use of oral terbinafine during postmarketing experience in individuals with and without pre-existing liver disease. In the majority of liver cases reported, the patients had serious underlying systemic conditions. The severity of hepatic events and/or their outcome may be worse in patients with active or chronic liver disease. Treatment with Interbi (terbinafine hydrochloride) should be discontinued if biochemical or clinical evidence of liver injury develops.

Interbi (terbinafine hydrochloride) is not recommended for patients with chronic or active liver disease. Before prescribing Interbi (terbinafine hydrochloride) , pre-existing liver disease should be assessed. Hepatotoxicity may occur in patients with and without pre-existing liver disease. Pretreatment serum transaminase (ALT and AST) tests are advised for all patients before taking Interbi (terbinafine hydrochloride). Patients prescribed Interbi (terbinafine hydrochloride) and/or their guardians should be warned to report immediately to their physician any symptoms of persistent nausea, anorexia, fatigue, vomiting, right upper abdominal pain or jaundice, dark urine or pale stools. Patients with these symptoms should discontinue taking Interbi (terbinafine hydrochloride) , and the patient's liver function should be immediately evaluated.

Monitoring Laboratory Tests

Pretreatment serum transaminase (ALT and AST) tests are advised for all patients before taking Interbi (terbinafine hydrochloride).

Hematological

Transient decreases in absolute lymphocyte counts (ALC) have been observed in clinical trials. In placebo-controlled trials, 8/465 subjects receiving Lamisil Tablets (1.7%) and 3/137 subjects receiving placebo (2.2%) had decreases in ALC to below 1000/mm³ on two or more occasions. In patients with known or suspected immunodeficiency, physicians should consider monitoring complete blood counts if treatment will exceed six weeks. Cases of severe neutropenia have been reported; these were reversible upon discontinuation of terbinafine, with or without supportive therapy. If clinical signs and symptoms suggestive of secondary infection occur, a complete blood count should be obtained. If the neutrophil count is ≤ 1,000 cells/mm³, Interbi (terbinafine hydrochloride) should be discontinued and supportive management started.

Skin Reactions

There have been post marketing reports of serious skin reactions (e.g., Stevens-Johnson Syndrome and toxic epidermal necrolysis) with oral terbinafine. If progressive skin rash occurs, treatment with Interbi (terbinafine hydrochloride) should be discontinued.

Renal Function

In patients with renal impairment (creatinine clearance < 50 mL/ min), the use of Interbi has not been adequately studied.

Lupus Erythenatosus

During postmarketing experience, precipitation and exacerbation of cutaneous and systemic lupus erythematosus have been reported in patients taking oral terbinafine. Therapy should be discontinued in patients with clinical signs and symptoms suggestive of lupus erythematosus.

Nonclinical Toxicology

Carcinogenesis, Mutugenesis, Impairment of Fertility

In a 28-month oral carcinogenicity study in rats, an increase in the incidence of liver tumors was observed in males at the highest dose tested, 69 mg/kg/day (2x the MRHD based on AUC comparisons of the parent terbinafine); however, even though dose-limiting toxicity was not achieved at the highest tested dose, higher doses were not tested.

The results of a variety of in vitro (mutations in >E. coli and S. typhimurium, DNA repair in rat hepatocytes, mutagenicity in Chinese hamster fibroblasts, chromosome aberration and sister chromatid exchanges in Chinese hamster lung cells), and in vivo (chromosome aberration in Chinese hamsters, micronucleus test in mice) genotoxicity tests gave no evidence of a mutagenic or clastogenic potential. Oral reproduction studies in rats at doses up to 300 mg/kg/day (approximately 12x the MRHD based on BSA comparisons) did not reveal any specific effects on fertility or other reproductive parameters. Intravaginal application of terbinafine hydrochloride at 150 mg/day in pregnant rabbits did not increase the incidence of abortions or premature deliveries nor affect fetal parameters.

Use In Specific Populations

Pregnancy

Pregnancy Category B.

Oral reproduction studies have been performed in rabbits and rats at doses up to 300 mg/kg/day [12x to 23x the Maximum Recommended Human Dose (MRHD), in rabbits and rats, respectively, based on body surface area (BSA) comparisons] and have revealed no evidence of impaired fertility or harm to the fetus due to terbinafine. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, and because treatment of onychomycosis can be postponed until after pregnancy is completed, it is recommended that Lamisil (terbinafine hydrochloride) Oral Granules not be initiated during pregnancy.

Nursing Mothers

After oral administration, terbinafine is present in breast milk of nursing mothers. The ratio of terbinafine in milk to plasma is 7:1. Treatment with Interbi (terbinafine hydrochloride) is not recommended in nursing mothers.

Pediatric Use

Interbi (terbinafine hydrochloride) was studied in two randomized, active-controlled trials in which 1021 subjects having a clinical diagnosis of tinea capitis confirmed by KOH microscopy were treated with Interbi (terbinafine hydrochloride) at the labeled dose for up to 6 weeks. The most common adverse events were nasopharyngitis, headache, pyrexia, cough, vomiting, and upper respiratory tract infection.

Geriatric Use

Interbi (terbinafine hydrochloride) has not been studied in geriatric patients.

Lamisil Cream has no influence on the ability to drive and use machines.

Clinical Studies Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Lamisil (terbinafine hydrochloride) Oral Granules

The data described below reflect exposure to terbinafine including 1042 subjects exposed for a median of 42 days. Interbi (terbinafine hydrochloride) was studied in 2 active-controlled trials (n=1042). The population was children aged 4 to 12 years old, 64% male and 36% female, 21% Caucasian, 47% Black, 32% Other. Baseline disease (dermatophyte) characteristics of subjects included 49% having T. tonsurans, 15% T. violaceum, 15% M. canis, 2% M. audouinii, and 1% others. Subjects received once daily, for 6 weeks, oral doses of Interbi (terbinafine hydrochloride) based on body weight: < 25kg 125 mg/day, 25-35kg 187.5 mg/day, and > 35kg 250 mg/day. Adverse events reported in the 2 trials are listed in the table below.

Table 2 Adverse Events ( ≥ 1%) in the Tinea Capitis Trials

In the pooled pivotal trials, 2% (17/1042) of subjects in the terbinafine group and 2% (6/507) in the griseofulvin group experienced discontinuation of study drug due to adverse events. The most common categories of adverse events causing discontinuation in those exposed to terbinafine included gastrointestinal disorders, skin and subcutaneous disorders, and infections and infestations.

No ophthalmologic safety signal was identified in the pooled pivotal trials. Ophthalmologic assessments included dilated fundoscopy to assess for refractile bodies in the retina, visual acuity assessment, and color vision testing. Of the 940 subjects in the terbinafine group and 471 subjects in the griseofulvin group who completed dilated fundoscopy at post-treatment visits, none of the subjects were found to have refractile bodies of the retina at baseline or end of treatment. For visual acuity, 1% (11/837) of subjects treated with terbinafine and 2% (7/426) of subjects treated with griseofulvin showed a doubling of visual angle after 6 weeks of treatment, while 2% (15/837) treated with terbinafine and 3% (12/426) treated with griseofulvin showed a halving of the visual angle after 6 weeks of treatment. Of subjects who completed yellow-blue color vision assessment for acquired defects, 5% (13/262) of subjects treated with terbinafine and 6% (8/129) of subjects treated with griseofulvin had color confusion on more than one symbol at week 6 than at baseline, while 13% (33/262) of subjects treated with terbinafine and 13% (17/129) of subjects treated with griseofulvin identified more symbols correctly at week 6 than at baseline.

Lamisil (terbinafine hydrochloride) Tablets

Adverse events reported in three US/Canadian placebo-controlled trials included diarrhea (6%), rashes (6%), dyspepsia (4%), nausea (3%), liver abnormalities (3%), pruritus (3%), taste disturbances (3%), abdominal pain (2%), and urticaria (1%).

Changes in the ocular lens and retina have been reported following the use of Lamisil Tablets in clinical trials in adult subjects with onychomycosis. The clinical significance of these changes is unknown.

Postmarketing Experience

The following adverse events have been identified during postapproval use of Lamisil. 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.

Adverse events reported with oral terbinafine use include: idiosyncratic and symptomatic hepatic injury and, cases of liver failure, some leading to death or liver transplant, serious skin reactions, severe neutropenia, thrombocytopenia, agranulocytosis, pancytopenia, anemia, angioedema and allergic reactions (including anaphylaxis).

Psoriasiform eruptions or exacerbation of psoriasis, acute generalized exanthematous pustulosis and precipitation and exacerbation of cutaneous and systemic lupus erythematosus have been reported. Oral terbinafine may cause taste disturbance (including taste loss) which usually recovers within several weeks after discontinuation of the drug. There have been reports of prolonged (greater than one year) taste disturbance. Taste disturbances have been reported to be severe enough to result in decreased food intake leading to significant and unwanted weight loss.

Other adverse reactions which have been reported include malaise, fatigue, arthralgia, myalgia, vomiting, acute pancreatitis, rhabdomyolysis, reduced visual acuity, visual field defects, and hair loss. Adverse events reported spontaneously since the drug was marketed include altered prothrombin time (prolongation and reduction) in patients concomitantly treated with warfarin.

Clinical experience regarding overdose with oral terbinafine is limited. Doses up to 5 grams in adults (20 times the therapeutic daily adult dose) have been reported without inducing serious adverse reactions. The symptoms of overdose included nausea, vomiting, abdominal pain, dizziness, rash, frequent urination, and headache.

The pharmacodynamics of Lamisil ® (terbinafine hydrochloride) Oral Granules is unknown.

The pharmacokinetics in children 4 to 8 years of age with tinea capitis was investigated in a pharmacokinetic study after single and repeated (for 42 days) oral administration of Interbi (terbinafine hydrochloride) (N=16), once daily, using the body weight groups and doses described in section 2.2. The systemic exposure (Cmax and AUC_0-24) of terbinafine in children had a relatively high inter-individual variability (ranging from 36 % to 64 %). At steady state the AUC_0-24 increased by a mean factor of 1.9 to 2.1 across doses. The mean (SD) effective half-life obtained from the observed accumulation was 26.7 (13.8) hrs and 30.5 (9.3) hrs for the 125 mg and 187.5 mg doses, respectively.

Systemic exposure to terbinafine in the children did not exceed the highest values of the systemic exposure in adults receiving repeated once daily doses of 250 mg Lamisil (terbinafine) Tablets. A population pharmacokinetic evaluation of oral terbinafine that included children 4-12 years of age and adults 18-45 years of age (N=113) found that clearance (CL/F) of terbinafine is dependent on body weight in a nonlinear manner. For a typical child of 25 kg CL/F was predicted to be 19 L/h and for a typical adult of 70 kg body weight it was predicted to be 27 L/h. Over the weight range for pediatric patients included in the analysis (14.1 kg-68 kg), the predicted CL/F ranged between 15.6 - 26.7 L/hr. In plasma, terbinafine is > 99% bound to plasma proteins. Prior to excretion, terbinafine is rapidly and extensively metabolized by at least seven CYP isoenzymes with major contributions from CYP2C9, CYP1A2, CYP3A4, CYP2C8 and CYP2C19. No metabolites have been identified that have antifungal activity similar to terbinafine. Approximately 70% of the administered dose is eliminated in the urine. In adult patients with renal impairment (creatinine clearance ≤ 50 mL/min) or hepatic cirrhosis, the clearance of terbinafine is decreased by approximately 50% compared to normal volunteers.

In long-term studies (up to 1 year) in rats and dogs no marked toxic effects were seen in either species up to oral doses of about 100 mg/kg a day. At high oral doses, the liver and possibly also the kidneys were identified as potential target organs.

In a two-year oral carcinogenicity study in mice, no neoplastic or other abnormal findings attributable to treatment were made up to doses of 130 (males) and 156 (females) mg/kg a day. In a two-year oral carcinogenicity study in rats at the highest dose level, 69 mg/kg a day, an increased incidence of liver tumours was observed in males. The changes, which may be associated with peroxisome proliferation, have been shown to be species-specific since they were not seen in the carcinogenicity study in mice or in other studies in mice, dogs or monkeys.

During the studies of high dose oral terbinafine in monkeys, refractile irregularities were observed in the retina at the higher doses (non-toxic effect level was 50 mg/kg). These irregularities were associated with the presence of a terbinafine metabolite in ocular tissue and disappeared after drug discontinuation. They were not associated with histological changes.

A standard battery of in vitro and in vivo genotoxicity tests revealed no evidence of a mutagenic or clastogenic potential for the drug.

No adverse effects on fertility or other reproduction parameters were observed in studies in rats or rabbits.

None known.

Not applicable.