1.1 Actinic Keratosis

Imiquimod Cream, 3.75% is indicated for the topical treatment of clinically typical visible or palpable, actinic keratoses (AK) of the full face or balding scalp in immunocompetent adults.

1.2 External Genital Warts

Imiquimod Cream, 3.75% is indicated for the treatment of external genital and perianal warts (EGW)/condyloma acuminata in patients 12 years or older.

1.3 Limitations of Use

Imiquimod cream has been evaluated in children ages 2 to 12 years with molluscum contagiosum and these studies failed to demonstrate efficacy [see Use in Specific Populations (8.4)].

Treatment with Imiquimod Cream has not been studied for prevention or transmission of human papillomavirus (HPV).

1.4 Unevaluated Populations

The safety and efficacy of Imiquimod Cream have not been established in the treatment of:

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urethral, intravaginal, cervical, rectal, or intra-anal human papilloma viral disease.

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actinic keratosis when treated with more than one 2-cycle treatment course in the same area.

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patients with xeroderma pigmentosum.

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superficial basal cell carcinoma.

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immunosuppressed patients.

2.1 Actinic Keratosis

Imiquimod Cream should be applied once daily before bedtime to the skin of the affected area (either entire face or balding scalp) for two 2-week treatment cycles separated by a 2-week no-treatment period. Imiquimod Cream should be applied as a thin film to the entire treatment area and rubbed in until the cream is no longer visible. Up to 0.5 grams (two full actuations of the pump) of Imiquimod Cream may be applied to the treatment area at each application. Imiquimod Cream should be left on the skin for approximately 8 hours, after which time the cream should be removed by washing the area with mild soap and water. The prescriber should demonstrate the proper application technique to maximize the benefit of Imiquimod Cream therapy.

Patients should wash their hands before and after applying Imiquimod Cream.

Avoid use in or on the lips and nostrils. Do not use in or near the eyes.

Local skin reactions in the treatment area are common [see Adverse Reactions (6.1)]. A rest period of several days may be taken if required by the patient’s discomfort or severity of the local skin reaction. However, neither 2-week treatment cycle should be extended due to missed doses or rest periods. A transient increase in lesion counts may be observed during treatment. Response to treatment cannot be adequately assessed until resolution of local skin reactions. The patient should continue dosing as prescribed. Treatment should continue for the full treatment course even if all actinic keratoses appear to be gone. Lesions that do not respond to treatment should be carefully re-evaluated and management reconsidered.

Prescribe no more than two 7.5 g pumps for the total 2-cycle treatment course.

2.2 External Genital Warts

Patients should apply a thin layer of Imiquimod Cream once a day to the external genital/perianal warts until total clearance or for up to 8 weeks. Patients should use up to 0.25 grams (one full actuation of the pump) at each application, which is a sufficient amount of cream to cover the wart area. Imiquimod Cream should be applied prior to normal sleeping hours and left on the skin for approximately 8 hours, then removed by washing the area with mild soap and water. The prescriber should demonstrate the proper application technique to maximize the benefit of Imiquimod Cream therapy.

Patients should wash their hands before and after applying Imiquimod Cream.

Local skin reactions at the treatment site are common [see Adverse Reactions (6.2)], and may necessitate a rest period of several days; resume treatment once the reaction subsides. Non-occlusive dressings, such as cotton gauze or cotton underwear, may be used in the management of skin reactions.

Prescribe up to two 7.5 g pumps for the total treatment course. Use of excessive amounts of cream should be avoided.

2.3 Pump Administration

Imiquimod Cream pumps should be primed before using for the first time by repeatedly depressing the actuator until cream is dispensed. It is not necessary to repeat this priming process during treatment.

5.1 Local Skin Reactions

Intense local skin reactions including skin weeping or erosion can occur after a few applications of Imiquimod Cream and may require an interruption of dosing [see Dosage and Administration (2) and Adverse Reactions (6)]. Imiquimod Cream has the potential to exacerbate inflammatory conditions of the skin, including chronic graft versus host disease.

Severe local inflammatory reactions of the female external genitalia can lead to severe vulvar swelling. Severe vulvar swelling can lead to urinary retention. Dosing should be interrupted or discontinued for severe vulvar swelling.

Administration of Imiquimod Cream is not recommended until the skin is healed from any previous drug or surgical treatment.

5.2 Systemic Reactions

Flu-like signs and symptoms may accompany, or even precede, local skin reactions and may include fatigue, nausea, fever, myalgias, arthralgias, malaise, and chills. An interruption of dosing and an assessment of the patient should be considered [see Adverse Reactions (6)].

Lymphadenopathy occurred in 2% of subjects with actinic keratosis treated with Imiquimod Cream, 3.75% and in 3% of subjects treated with Imiquimod Cream, 2.5% [see Adverse Reactions (6)].This reaction resolved in all subjects by 4 weeks after completion of treatment.

5.3 Ultraviolet Light Exposure Risks

Exposure to sunlight (including sunlamps) should be avoided or minimized during use of Imiquimod Cream. Patients should be warned to use protective clothing (e.g., a hat) when using Imiquimod Cream. Patients with sunburn should be advised not to use Imiquimod Cream until fully recovered. Patients who may have considerable sun exposure (e.g., due to their occupation) and those patients with inherent sensitivity to sunlight should exercise caution when using Imiquimod Cream.

In an animal photocarcinogenicity study, imiquimod cream shortened the time to skin tumor formation [see Nonclinical Toxicology (13.1)]. The enhancement of ultraviolet carcinogenicity is not necessarily dependent on phototoxic mechanisms. Therefore, patients should minimize or avoid natural or artificial sunlight exposure.

5.4 Increased Risk of Adverse Reactions with Concomitant Imiquimod Use

Concomitant use of Imiquimod Cream and any other imiquimod products, in the same treatment area, should be avoided since they contain the same active ingredient (imiquimod) and may increase the risk for and severity of local skin reactions.

The safety of concomitant use of Imiquimod Cream and any other imiquimod products has not been established and should be avoided since they contain the same active ingredient (imiquimod) and may increase the risk for and severity of systemic reactions.

5.5 Immune Cell Activation in Autoimmune Disease

Imiquimod Cream should be used with caution in patients with pre-existing autoimmune conditions because imiquimod activates immune cells [see Clinical Pharmacology (12.2)].

6.1 Clinical Trials Experience: Actinic Keratosis

The data described below reflect exposure to Imiquimod Cream or vehicle in 479 subjects enrolled in two double-blind, vehicle-controlled trials. Subjects applied up to two packets of Imiquimod Cream or vehicle daily to the skin of the affected area (either entire face or balding scalp) for two 2-week treatment cycles separated by a 2-week no-treatment period.

Local skin reactions were recorded as adverse reactions only if they extended beyond the treatment area, if they required any medical intervention, or they resulted in patient discontinuation from the study. The incidence and severity of selected local skin reactions are shown in Table 2.

Overall, in the clinical trials, 11% (17/160) of subjects in the Imiquimod Cream, 3.75% arm, 7% (11/160) of subjects in the Imiquimod Cream, 2.5% arm, and 0% in the vehicle cream arm required rest periods due to adverse local skin reactions.

Other adverse reactions observed in subjects treated with Imiquimod Cream include: application site bleeding, application site swelling, chills, dermatitis, herpes zoster, insomnia, lethargy, myalgia, pancytopenia, pruritus, squamous cell carcinoma, and vomiting.

6.2 Clinical Trials Experience: External Genital Warts

In two double-blind, placebo-controlled studies, 602 subjects applied up to one packet of Imiquimod Cream or vehicle daily for up to 8 weeks.

The most frequently reported adverse reactions were application site reactions and local skin reactions. Selected adverse reactions are listed in Table 3.

Local skin reactions were recorded as adverse reactions only if they extended beyond the treatment area, if they required any medical intervention, or they resulted in patient discontinuation from the study. The incidence and severity of selected local skin reactions are shown in Table 4.

The frequency and severity of local skin reactions were similar in both genders, with the following exceptions: a) flaking/scaling occurred in 40% of men and in 26% of women and b) scabbing/crusting occurred in 34% of men and in 18% of women.

In the clinical trials, 32% (126/400) of subjects who used Imiquimod Cream and 2% (4/202) of subjects who used vehicle cream discontinued treatment temporarily (required rest periods) due to adverse local skin reactions, and 1% (3/400) of subjects who used Imiquimod Cream discontinued treatment permanently due to local skin/application site reactions.

Other adverse reactions reported in subjects treated with Imiquimod Cream include: rash, back pain, application site rash, application site cellulitis, application site excoriation, application site bleeding, scrotal pain, scrotal erythema, scrotal ulcer, scrotal edema, sinusitis, nausea, pyrexia, and influenza-like symptoms.

6.3 Postmarketing Experience

The following adverse reactions have been identified during post-approval use of imiquimod. Because these 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.

Application Site Disorders: tingling at the application site

Body as a Whole: angioedema

Cardiovascular: capillary leak syndrome, cardiac failure, cardiomyopathy, pulmonary edema, arrhythmias (tachycardia, supraventricular tachycardia, atrial fibrillation, palpitations), chest pain, ischemia, myocardial infarction, syncope

Endocrine: thyroiditis

Gastrointestinal System Disorders: abdominal pain

Hematological: decreases in red cell, white cell and platelet counts (including idiopathic thrombocytopenic purpura), lymphoma

Hepatic: abnormal liver function

Infections and Infestations: herpes simplex

Musculoskeletal System Disorders: arthralgia

Neuropsychiatric: agitation, cerebrovascular accident, convulsions (including febrile convulsions), depression, insomnia, multiple sclerosis aggravation, paresis, suicide

Respiratory: dyspnea

Urinary System Disorders: proteinuria, urinary retention, dysuria

Skin and Appendages: exfoliative dermatitis, erythema multiforme,hyperpigmentation, hypertrophic scar, hypopigmentation

Vascular: Henoch-Schonlein purpura syndrome

8.1 Pregnancy

8.3 Nursing Mothers

It is not known whether imiquimod is excreted in human milk following use of Imiquimod Cream. Because many drugs are excreted in human milk, caution should be exercised when Imiquimod Cream is administered to nursing women.

8.4 Pediatric Use

AK is a condition not generally seen within the pediatric population. The safety and effectiveness of Imiquimod Cream for AK in patients less than 18 years of age have not been established.

Safety and effectiveness in patients with external genital/perianal warts below the age of 12 years have not been established.

Imiquimod 5% cream was evaluated in two randomized, vehicle-controlled, double-blind trials involving 702 pediatric subjects with molluscum contagiosum (MC) (470 exposed to imiquimod; median age 5 years, range 2-12 years). Subjects applied imiquimod cream or vehicle 3 times weekly for up to 16 weeks. Complete clearance (no MC lesions) was assessed at Week 18. In Study 1, the complete clearance rate was 24% (52/217) in the imiquimod cream group compared with 26% (28/106) in the vehicle group. In Study 2, the clearance rates were 24% (60/253) in the imiquimod cream group compared with 28% (35/126) in the vehicle group. These studies failed to demonstrate efficacy.

Similar to the studies conducted in adults, the most frequently reported adverse reaction from two studies in children with molluscum contagiosum was application site reaction. Adverse events which occurred more frequently in imiquimod-treated subjects compared with vehicle-treated subjects generally resembled those seen in studies in indications approved for adults and also included otitis media (5% imiquimod vs. 3% vehicle) and conjunctivitis (3% imiquimod vs. 2% vehicle).

Erythema was the most frequently reported local skin reaction. Severe local skin reactions reported by imiquimod-treated subjects in the pediatric studies included erythema (28%), edema (8%), scabbing/crusting (5%), flaking/scaling (5%), erosion (2%) and weeping/exudate (2%).

Systemic absorption of imiquimod across the affected skin of 22 subjects aged 2 to 12 years with extensive MC involving at least 10% of the total body surface area was observed after single and multiple doses at a dosing frequency of three applications per week for 4 weeks. The investigator determined the dose applied, either 1, 2 or 3 packets per dose, based on the size of the treatment area and the subject’s weight. The overall median peak serum drug concentrations at the end of Week 4 was between 0.26 and 1.06 ng/mL except in a 2-year-old female who was administered 2 packets of study drug per dose, had a Cmax of 9.66 ng/mL after multiple dosing. Children aged 2-5 years received doses of 12.5 mg (one packet) or 25 mg (two packets) of imiquimod and had median multiple-dose peak serum drug levels of approximately 0.2 or 0.5 ng/mL, respectively. Children aged 6-12 years received doses of 12.5 mg, 25 mg, or 37.5 mg (three packets) and had median multiple dose serum drug levels of approximately 0.1, 0.15, or 0.3 ng/mL, respectively. Among the 20 subjects with evaluable laboratory assessments, the median WBC count decreased by 1.4*109/L and the median absolute neutrophil count decreased by 1.42*109/L.

8.5 Geriatric Use

Of the 320 subjects treated with Imiquimod Cream in the AK clinical studies, 150 subjects (47%) were 65 years or older. No overall differences in safety or effectiveness were observed between these subjects and younger subjects.

Clinical studies of Imiquimod Cream for EGW did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Of the 400 subjects treated with Imiquimod Cream, 3.75% in the EGW clinical studies, 5 subjects (1%) were 65 years or older.

12.1 Mechanism of Action

The mechanism of action of Imiquimod Cream in treating AK and EGW lesions is unknown.

12.2 Pharmacodynamics

The pharmacodynamics of Imiquimod Cream are unknown.

Imiquimod is a Toll-like receptor 7 agonist that activates immune cells. Topical application to skin is associated with increases in markers for cytokines and immune cells.

12.3 Pharmacokinetics

Following dosing with two packets of Imiquimod Cream, 3.75% once daily (18.75 mg imiquimod/day) for up to 3 weeks, systemic absorption of imiquimod was observed in all subjects when Imiquimod Cream was applied to the face and/or scalp in 17 subjects with at least 10 AK lesions. The mean peak serum imiquimod concentration at the end of the trial was approximately 0.323 ng/mL. The median time to maximal concentrations (Tmax) occurred at 9 hours after dosing. Based on the plasma half-life of imiquimod observed at the end of the study, 29.3±17.0 hours, steady-state concentrations can be anticipated to occur by Day 7 with once-daily dosing.

Systemic absorption of imiquimod (up to 9.4 mg [one packet]) across the affected skin of 18 subjects with EGW was observed with once daily dosing for 3 weeks in all subjects. The subjects had either a minimum of 8 warts (range 8-93) or a surface area involvement of greater than 100 mm2 (range 15-620 mm2) at study entry. The mean peak serum imiquimod concentration at Day 21 was 0.488 +/- 0.368 ng/mL. The median time to maximal concentrations (Tmax) occurred 12 hours after dosing. Based on the plasma half-life of imiquimod observed at the end of the study, 24.1 +/- 12.4 hours, steady-state concentrations can be anticipated to occur by day 7 with once daily dosing. Because of the small number of subjects present (13 males, 5 females) it was not possible to select out or do an analysis of absorption based on gender/site of application.

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

In an oral (gavage) rat carcinogenicity study, imiquimod was administered to Wistar rats on a 2X/week (up to 6 mg/kg/day) or daily (3 mg/kg/day) dosing schedule for 24 months. No treatment-related tumors were noted in the oral rat carcinogenicity study up to the highest doses tested in this study of 6 mg/kg administered 2X/week in female rats (7.1X MRHD based on weekly AUC comparisons), 4 mg/kg administered 2X/week in male rats (6.1X MRHD based on weekly AUC comparisons) or 3 mg/kg administered 7X/week to male and female rats (12X MRHD based on weekly AUC comparisons).

In a dermal mouse carcinogenicity study, imiquimod cream (up to 5 mg/kg/application imiquimod or 0.3% imiquimod cream) was applied to the backs of mice 3X/week for 24 months. A statistically significant increase in the incidence of liver adenomas and carcinomas was noted in high-dose male mice compared to control male mice (21X MRHD based on weekly AUC comparisons). An increased number of skin papillomas was observed in vehicle cream control group animals at the treated site only.

In a 52-week dermal photocarcinogenicity study, the median time to onset of skin tumor formation was decreased in hairless mice following chronic topical dosing (3X/week; 40 weeks of treatment followed by 12 weeks of observation) with concurrent exposure to UV radiation (5 days per week) with vehicle alone. No additional effect on tumor development beyond the vehicle effect was noted with the addition of the active ingredient, imiquimod, to the vehicle cream.

Imiquimod revealed no evidence of mutagenic or clastogenic potential based on the results of five in vitro genotoxicity tests (Ames assay, mouse lymphoma L5178Y assay, Chinese hamster ovary cell chromosome aberration assay, human lymphocyte chromosome aberration assay and SHE cell transformation assay) and three in vivo genotoxicity tests (rat and hamster bone marrow cytogenetics assay and a mouse dominant lethal test).

Daily oral administration of imiquimod to rats, throughout mating, gestation, parturition and lactation, demonstrated no effects on growth, fertility or reproduction, at doses up to 25X MRHD based on AUC comparisons.

14.1 Actinic Keratosis

In two double-blind, randomized, vehicle-controlled clinical studies, 479 subjects with AK were treated with Imiquimod Cream, 3.75%, Imiquimod Cream, 2.5%, or vehicle cream. Studies enrolled subjects 18 years of age or older with 5 to 20 typical visible or palpable AK lesions of the face or scalp. Study cream was applied to either the entire face (excluding ears) or balding scalp once daily for two 2-week treatment cycles separated by a 2-week no-treatment period. Subjects then continued in the study for an 8-week follow-up period during which they returned for clinical observations and safety monitoring. Study subjects ranged from 36 to 90 years of age and 54% had Fitzpatrick skin type I or II. All Imiquimod Cream-treated subjects were Caucasians.

On a scheduled dosing day, up to two packets of the study cream were applied to the entire treatment area prior to normal sleeping hours and left on for approximately 8 hours. Efficacy was assessed by AK lesion counts at the 8-week post-treatment visit. All AKs in the treatment area were counted, including baseline lesions as well as lesions which appeared during therapy.

Complete clearance required absence of any lesions including those that appeared during therapy in the treatment area. Complete and partial clearance rates are shown in the tables below. Partial clearance rate was defined as the percentage of subjects in whom the number of baseline AKs was reduced by 75% or more. The partial clearance rate was measured relative to the numbers of AK lesions at baseline.

During the course of treatment, 86% (138/160) of Imiquimod Cream, 3.75% subjects and 84% (135/160) of Imiquimod Cream, 2.5% subjects experienced a transient increase in lesions evaluated as actinic keratoses relative to the number present at baseline within the treatment area.

14.2 External Genital Warts

In two double-blind, randomized, placebo-controlled clinical studies, 601 subjects with EGW were treated with 3.75% imiquimod cream, or a matching placebo cream. Studies enrolled subjects aged from 15 to 81 years. The baseline wart area ranged from 6 to 5579 mm2 (median 60 mm2) and the baseline wart count ranged from 2 to 48 warts. Most subjects had two or more treated anatomic areas at baseline. Anatomic areas included: inguinal, perineal, and perianal areas (both genders); the glans penis, penis shaft, scrotum, and foreskin (in men); and the vulva (in women). Up to one packet of study cream was applied once daily. The study cream was applied to all warts prior to normal sleeping hours and left on for approximately 8 hours. Subjects continued applying the study cream for up to 8 weeks, stopping if they achieved complete clearance of all (baseline and new) warts in all anatomic areas. Subjects who achieved complete clearance of all warts at any time up to the Week 16 visit entered a 12-week follow-up period to assess recurrence.

Complete clearance was defined as clearance of all warts (baseline and new) in all anatomic areas within 16 weeks from baseline. The complete clearance rates are shown in Table 7. The proportions of subjects who achieved complete clearance at or before a given week (cumulative proportion) for the combined studies are shown in Figure 1. Complete clearance rates by gender for the combined studies are shown in Table 8.

Figure 1: Cumulative Proportion of Subjects Achieving Complete Clearance of External Genital Warts by a Given Week (Combined Studies)



 

Of the 113 Imiquimod Cream, 3.75%-treated subjects who achieved complete clearance in the two studies, 17 (15%) subjects had a recurrence within 12 weeks.

No studies were conducted directly comparing the 3.75% and 5% concentrations of imiquimod cream in the treatment of external genital warts.

Store at 25°C (77°F); excursions permitted to 15° to 30°C (59° to 86°F) [see USP Controlled Room Temperature]. Avoid freezing.

Store Imiquimod Cream pumps upright.