6.1 Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed 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.

During clinical trials, 2,047 subjects with inflammatory lesions of rosacea received ivermectin cream once daily. A total of 1,555 subjects were treated once daily for more than 12 weeks, and 519 for approximately one year.

Adverse reactions, reported in less than or equal to 1% of subjects treated with ivermectin cream for at least 3 months in vehicle-controlled clinical trials, included skin burning sensation and skin irritation.

6.2 Postmarketing Experience

Because adverse reactions 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. Local adverse reactions: contact dermatitis and allergic dermatitis.

8.1 Pregnancy

Pregnancy Category C.

There are no adequate and well-controlled studies in pregnant women. Ivermectin cream should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Note: The animal multiples of human exposure calculations were based on AUC comparisons. The maximum topical human dose (MTHD) of ivermectin cream is 1 g applied once daily.

Systemic embryofetal development studies were conducted in rats and rabbits. Oral doses of 1.5 mg/kg/day, 4 mg/kg/day, and 12 mg/kg/day ivermectin were administered during the period of organogenesis (gestational days 6 to 17) to pregnant female rats. Maternal death occurred at 12 mg/kg/day (1909X MTHD). Cleft palate occurred in the fetuses from the 12 mg/kg/day (1909X MTHD) group. No treatment related effects on embryofetal toxicity or teratogenicity were noted at 4 mg/kg/day (708X MTHD). Oral doses of 0.5 mg/kg/day, 1.5 mg/kg/day, 2.5 mg/kg/day, 3.5 mg/kg/day, and 4.5 mg/kg/day ivermectin were administered during the period of organogenesis (gestational days 7 to 20) to pregnant female rabbits. Maternal death occurred at doses greater than or equal to 2.5 mg/kg/day (72X MTHD). Carpal flexure occurred in the fetuses from the 4.5 mg/kg/day (354X MTHD) group. Fetal weight decrease was noted at 3.5 mg/kg/day (146X MTHD). No treatment related effects on embryofetal toxicity were noted at 2.5 mg/kg/day (72X MTHD) and no treatment related effects on teratogenicity were noted at 3.5 mg/kg/day (146X MTHD).

A pre- and post-natal development study was conducted in rats. Oral doses of 1 mg/kg/day, 2 mg/kg/day, and 4 mg/kg/day ivermectin were administered to pregnant female rats during gestational days 6 to 20 and lactation days 2 to 20. Neonatal death occurred at doses greater than or equal to 2 mg/kg/day. Behavior development of newborn rats was adversely affected at all doses.

8.3 Nursing Mothers

Following oral administration, ivermectin is excreted in human milk in low concentrations. Excretion in human milk following topical administration has not been evaluated. In oral studies in rats, ivermectin was excreted in the milk of nursing mothers and neonatal toxicity was observed in the litters. The blood-brain barrier in neonatal rats may not be fully developed at birth. Because of the potential for serious adverse reactions from ivermectin cream in nursing infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

8.4 Pediatric Use

Safety and effectiveness of ivermectin cream in pediatric patients have not been established.

8.5 Geriatric Use

Of the 1,371 subjects in the two pivotal clinical studies of ivermectin cream, 170 (12.4%) were 65 and over, while 37 (2.7%) were 75 and over. No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.

12.1 Mechanism of Action

The mechanism of action of ivermectin cream in treating rosacea lesions is unknown.

12.2 Pharmacodynamics

Cardiac Electrophysiology

At therapeutic doses, ivermectin cream is not expected to prolong QTc interval.

12.3 Pharmacokinetics

Absorption

The absorption of ivermectin from ivermectin cream was evaluated in a clinical trial in 15 adult male and female subjects with severe papulopustular rosacea applying 1 g ivermectin cream, 1% once daily. At steady state (after 2 weeks of treatment), the highest mean ± standard deviation) plasma concentrations of ivermectin peaked (Tmax) at 10 ± 8 hours post-dose, the maximum concentration (Cmax) was 2.10 ± 1.04 ng/mL (range: 0.69 to 4.02 ng/mL) and the area under the concentration curve (AUC0-24hr) was 36.14 ± 15.56 ng.hr/mL (range: 13.69 to 75.16 ng•hr/mL). In addition, systemic exposure assessment in longer treatment duration (Phase 3 studies) showed that there was no plasma accumulation of ivermectin over the 52-week treatment period.

Distribution

An in vitro study demonstrated that ivermectin is greater than 99% bound to plasma proteins and is bound primarily to human serum albumin. No significant binding of ivermectin to erythrocytes was observed.

Metabolism

In vitro studies using human hepatic microsomes and recombinant CYP450 enzymes have shown that ivermectin is primarily metabolized by CYP3A4. In vitro studies show that ivermectin at therapeutic concentrations does not inhibit the CYP450 isoenzymes 1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, 3A4 or 4A11, or induce 1A2, 2B6, 2C9 or 3A4.

Excretion

The apparent terminal half-life averaged 6.5 days (mean ± standard deviation: 155± 40 hours, range 92 to 238 hours) in patients receiving a once daily cutaneous application of ivermectin cream for 28 days.

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

In a 2-year dermal mouse carcinogenicity study, ivermectin was administered to CD-1 mice at topical doses of 1, 3, and 10 mg/kg/day (0.1%, 0.3% and 1% ivermectin cream applied at 2 mL/kg/day). No drug-related tumors were noted in this study up to the highest dose evaluated in this study of 10 mg/kg/day (747X maximum topical human dose (MTHD)).

In a 2-year oral rat carcinogenicity study, ivermectin was administered to Wistar rats at gavage doses of 1 mg/kg/day, 3 mg/kg/day, and 9 mg/kg/day. A statistically significant increase in the incidence of hepatocellular adenoma was noted in males treated with 9 mg/kg/day (1766X MTHD) ivermectin. The clinical relevance of this finding is unknown. No drug-related tumors were noted in females up to the highest dose evaluated in this study of 9 mg/kg/day (1959X MTHD). No drug-related tumors were noted in males at doses less than or equal to 3 mg/kg/day (599X MTHD).

Ivermectin revealed no evidence of genotoxic potential based on the results of two in vitro genotoxicity tests (the Ames test and the L5178Y/TK+/- mouse lymphoma assay) and one in vivo genotoxicity test (rat micronucleus assay).

In a fertility study, oral doses of 0.1 mg/kg/day, 1 mg/kg/day, and 9 mg/kg/day ivermectin were administered to male and female rats. Mortality occurred at 9 mg/kg/day (1027X MTHD). The precoital period was generally prolonged at 9 mg/kg/day. No treatment related effects on fertility or mating performance were noted at doses less than or equal to 1 mg/kg/day (68X MTHD).