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 ≤ 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

Risk Summary

The available data on the use of ivermectin, including ivermectin cream, in pregnant women are insufficient to establish a drug- associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes.

In animal reproduction studies, ivermectin induced adverse developmental outcomes when orally administered to pregnant rats and rabbits during the period of organogenesis at doses 1909 or 354 times the maximum recommended human dose (MRHD), respectively. These orally administered doses were maternally toxic to pregnant rats and rabbits. In a pre-and postnatal developmental study in rats, neonatal toxicity and adverse effects on behavioral development were observed when ivermectin was orally administered to pregnant females during gestation and lactation (see Data).

The 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 to 4% and 15 to 20%, respectively.

Data

Human Data
No adequate and well-controlled trials of ivermectin cream have been conducted in pregnant women. Retrospective observational studies evaluated pregnancy outcomes in over 700 women in various stages of pregnancy who received oral ivermectin for the treatment of soil-transmitted helminths in rural Africa. In an additional, randomized open-label trial, 397 pregnant women in their second trimester received a single dose of oral ivermectin, or ivermectin plus albendazole, for soil-transmitted helminths. When compared with a pregnant, untreated population, no differences in pregnancy outcomes were observed between the treated and untreated populations. These studies cannot definitively establish or exclude any drug-associated risk during pregnancy, because either the timing of administration during gestation was not accurately ascertained or the administration occurred only during the second trimester.

Animal Data

Systemic embryofetal development studies were conducted in rats and rabbits. Oral doses of 1.5, 4, and
12 mg/kg/day ivermectin were administered during the period of organogenesis to pregnant female rats. Maternal death occurred at 12 mg/kg/day [1909 times the MRHD based on area under the curve (AUC) comparison]. Cleft palate occurred in the fetuses from the 12 mg/kg/day (1909 times the MRHD based on AUC comparison) group. No treatment related embryofetal toxicity or malformations were noted at 4 mg/kg/day (708 times the MRHD based on AUC comparison). Oral doses of 0.5, 1.5, 2.5, 3.5 and 4.5 mg/kg/day ivermectin were administered during the period of organogenesis to pregnant female rabbits. Maternal death occurred at doses ≥ 2.5 mg/kg/day (72 times the MRHD based on AUC comparison). Carpal flexure occurred in the fetuses from the 4.5 mg/kg/day (354 times the MRHD based on AUC comparison) group. Fetal weight decrease was noted at 3.5 mg/kg/day (146 times the MRHD based on AUC comparison). No treatment related embryofetal toxicity or malformations were noted at 2.5 mg/kg/day (72 times the MRHD based on AUC comparison).

A pre- and post-natal development study was conducted in rats. Oral doses of 1, 2 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 ≥ 2 mg/kg/day. Behavior development of newborn rats was adversely affected at all doses.

8.2 Lactation

Risk Summary

The presence of ivermectin in human milk following topical administration of ivermectin has not been evaluated. There are no data available regarding the effects of ivermectin on milk production. Published literature suggests that ivermectin was detectable in human milk in 4 lactating women after a single 150 mcg/kg oral dose of ivermectin. However, there is insufficient information from this report to determine the effects of ivermectin on the breastfed infant. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for ivermectin cream and any potential adverse effects on the breastfed infant from ivermectin cream or from the underlying maternal conditions. 

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 (747 times the MRHD based on AUC comparison).

In a 2-year oral rat carcinogenicity study, ivermectin was administered to Wistar rats at gavage doses of 1, 3, 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 (1766 times the MRHD based on AUC comparison) 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 (1959 times the MRHD based on AUC comparison). No drug-related tumors were noted in males at doses ≤ 3 mg/kg/day (599 times the MRHD based on AUC comparison).

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, 1, and 9 mg/kg/day ivermectin were administered to male and female rats. Mortality occurred at 9 mg/kg/day (1027 times the MRHD based on AUC comparison). The precoital period was generally prolonged at 9 mg/kg/day. No treatment related effects on fertility or mating performance were noted at doses ≤ 1 mg/kg/day (68 times the MRHD based on AUC comparison).