If a reaction suggesting sensitivity or chemical irritation occurs, use of the medication should be discontinued. Exposure to sunlight, including sunlamps, should be minimized during the use of AVITA® Gel, and patients with sunburn should be advised not to use the product until fully recovered because of heightened susceptibility to sunlight as a result of the use of tretinoin. Patients who may be required to have considerable sun exposure due to occupation and those with inherent sensitivity to the sun should exercise particular caution. Use of sunscreen products and protective clothing over treated areas is recommended when exposure cannot be avoided. Weather extremes, such as wind or cold, also may be irritating to patients under treatment with tretinoin.
AVITA® (tretinoin gel) Gel, 0.025% should be kept away from the eyes, the mouth, the paranasal creases, and mucous membranes. Topical use may induce severe local erythema and peeling at the site of application. If the degree of local irritation warrants, patients should be directed to temporarily use the medication less frequently, discontinue use temporarily, or discontinue use altogether. Efficacy at reduced frequencies of application has not been established. Tretinoin has been reported to cause severe irritation on eczematous skin and should be used with utmost caution in patients with this condition.
Information for Patients
See attached Patient Package Insert.
Carcinogenesis, Mutagenesis and Impairment of Fertility
In a dermal mouse carcinogenicity study with AVITA® Gel, tretinoin was administered to CD1 mice at topical doses of 0.027 mg/kg (0.003% gel), 0.072 mg/kg (0.008% gel), and 0.225 mg/kg (0.025% gel) for 2 years (5 doses/week). No drug-related tumors were noted in this mouse carcinogenicity study up to the highest dose evaluated in this study of 0.225 mg/kg in both male and female mice, which was 2.6 times the recommended human topical clinical dose (based on weekly dose BSA comparison). For purposes of comparisons of the animal exposure to human exposure, the “recommended human topical clinical dose” is defined as 1.0 g of 0.025% AVITA® Gel applied daily to a 50 kg person. In a chronic, two-year bioassay of vitamin A acid in mice performed by Tsubura and Yamamoto, generalized amyloid deposition was reported in all vitamin A treated groups in the basal layer of the skin. In CD-1 mice, a similar study reported hyalinization at the treated skin sites and the incidence of this finding was 0/50, 3/50, 3/50, and 2/50 in male mice and 1/50, 0/50, 4/50, and 2/50 in female mice from the vehicle control, 0.25 mg/kg, 0.5 mg/kg, and 1 mg/kg groups, respectively.
Studies in hairless albino mice suggest that tretinoin may enhance the tumorigenic potential of carcinogenic doses of UVA and UVB light from a solar simulator. In other studies, when lightly pigmented hairless mice treated with Tretinoin were exposed to carcinogenic doses of UVA/UVB light, the incidence and rate of development of skin tumors were either reduced or no effect was seen. Due to significantly different experimental conditions, no strict comparison of these disparate data is possible at this time. Although the significance of these studies to humans is not clear, patients should minimize exposure to sun.
The mutagenic potential of tretinoin was evaluated in the Ames assay and in the in vivo mouse micronucleus assay, both of which were negative.
Dermal Segment I and III studies with AVITA® Gel have not been performed in any species. In oral Segment I and Segment III studies in rats with tretinoin, decreased survival of neonates and growth retardation were observed at doses in excess of 2 mg/kg/day ( > 400 times the average recommended human topical clinical dose).
Pregnancy Category C.
Oral tretinoin has been shown to be teratogenic in rats, mice, rabbits, hamsters, and subhuman primates. It was teratogenic and fetotoxic in rats when given orally in doses 1000 times the average recommended human topical clinical dose. However, variations in teratogenic doses among various strains of rats have been reported. In the cynomolgus monkey, which metabolically is closer to humans for tretinoin than other species examined, fetal malformations were reported at oral doses of 10 mg/kg/day or greater, but none were observed at 5 mg/kg/day (1000 times the average recommended human topical clinical dose), although increased skeletal variations were observed at all doses. Dose-related increased embryolethality and abortion were reported. Similar results have also been reported in pigtail macaques.
Topical tretinoin in animal teratogenicity tests has generated equivocal results. There is evidence for teratogenicity (shortened or kinked tail) of topical tretinoin in Wistar rats at doses greater than 1 mg/kg/day (200 times the recommended human topical clinical dose). Anomalies (humerus: short 13%, bent 6%; os parietal incompletely ossified 14%) have also been reported in rats when 10 mg/kg/day was dermally applied.
Topical tretinoin (AVITA® Gel, 0.025%) has been shown to be teratogenic in rabbits when given in doses 364 times the topical human dose for gel (assuming a 50 kg adult applies 1.0 g of 0.025% gel topically). In this study, increased incidence of cleft palate and hydrocephaly was reported in the tretinoin-treated animals.
There are other reports, in New Zealand White rabbits with doses of approximately 80 times the recommended human topical clinical dose, of an increased incidence of domed head and hydrocephaly, typical of retinoid-induced fetal malformations in this species.
When given subcutaneously to rabbits, tretinoin was teratogenic at 2 mg/kg/day but not at 1 mg/kg/day. These doses are approximately 400 and 200 times, respectively, the human topical dose of tretinoin gel, 0.025% (assuming a 50 kg adult applies 1.0 g of 0.025% gel topically).
In contrast, several well-controlled animal studies have shown that dermally applied tretinoin was not teratogenic at doses of 100 and 200 times the recommended human topical clinical dose, in rats and rabbits, respectively.
With widespread use of any drug, a small number of birth defect reports associated temporally with the administration of the drug would be expected by chance alone. Thirty cases of temporally associated congenital malformations have been reported during two decades of clinical use of another formulation of topical tretinoin (Retin-A). Although no definite pattern of teratogenicity and no causal association have been established from these cases, 5 of the reports describe the rare birth defect category, holoprosencephaly (defects associated with incomplete midline development of the forebrain). The significance of these spontaneous reports in terms of risk to the fetus is not known.
Dermal tretinoin has been shown to be fetotoxic in rabbits when administered in doses 100 times the recommended topical human clinical dose. Oral tretinoin has been shown to be fetotoxic in rats when administered in doses 500 times the recommended topical human clinical dose. There are, however, no adequate and well-controlled studies in pregnant women. AVITA® (tretinoin gel) Gel, 0.025% should not be used during pregnancy.
It is not known whether this drug is excreted in human milk, caution should be exercised when AVITA® Gel is administered to a nursing woman.This monograph has been modified to include the generic and brand name in many instances.
Last reviewed on RxList: 8/18/2011
Additional Avita Information
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