ZYCLARA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ZYCLARA (ZYCLARA).
Imiquimod acts as an immune response modifier. It activates toll-like receptor 7 (TLR7), leading to the production of cytokines such as interferon-alpha, interleukin-12, and tumor necrosis factor-alpha, which stimulate both innate and adaptive immune responses.
| Metabolism | Imiquimod is metabolized primarily via oxidative pathways, with CYP1A2 and CYP2A6 as the main cytochrome P450 enzymes involved. It is also conjugated to form glucuronide and sulfate metabolites. |
| Excretion | Renal: 80% as unchanged drug; Fecal: <15% as metabolites; Biliary: minimal (<1%) |
| Half-life | Terminal elimination half-life: 27 hours (range 22-33 hours) following topical application; clinical context: allows once-daily dosing |
| Protein binding | Imiquimod: ~99% bound to plasma proteins (albumin and α1-acid glycoprotein) |
| Volume of Distribution | Volume of distribution: not clinically determined after topical application; systemic absorption minimal (<1% of applied dose); Vd not applicable |
| Bioavailability | Topical: systemic absorption <1% of applied dose (mean 0.2-0.9%); oral: not available |
| Onset of Action | Topical: Clinical improvement (reduction in actinic keratosis lesions) typically observed within 4 weeks of once-daily application |
| Duration of Action | Duration of action: Not well defined; treatment course is 2-4 weeks; lesion clearance continues for up to 8 weeks post-treatment; repeat cycles may be needed |
| Molecular Weight | 288.26 |
Apply a thin layer to the affected area once daily at bedtime for 2 weeks (for actinic keratosis) or up to 16 weeks (for superficial basal cell carcinoma). Not for ophthalmic, oral, or intravaginal use.
| Dosage form | CREAM |
| Renal impairment | No dosage adjustment required for renal impairment. |
| Liver impairment | No dosage adjustment required for hepatic impairment. |
| Pediatric use | Safety and efficacy in pediatric patients have not been established; use is not recommended for patients under 18 years. |
| Geriatric use | No specific dosage adjustment required; clinical studies included patients aged 65 and older with no overall differences in safety or efficacy observed. |
| 1st trimester | Contraindicated due to risk of fetal harm. Animal studies show adverse effects. |
| 2nd trimester | Contraindicated due to risk of fetal harm. |
| 3rd trimester | Contraindicated near term; may cause premature closure of ductus arteriosus. |
Clinical note
Comprehensive clinical and safety monograph for ZYCLARA (ZYCLARA).
| Placental transfer | Crosses placenta; fetal levels ~30% of maternal levels. |
| Breastfeeding | Excreted in breast milk in low amounts. Use caution; consider risk of infant NSAID exposure. |
| Lactation Rating | L3 (Moderately Safe) |
■ FDA Black Box Warning
None.
| Serious Effects |
Known hypersensitivity to diclofenacHistory of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDsTreatment of peri-operative pain in the setting of coronary artery bypass graft (CABG) surgeryAdvanced renal diseaseActive gastrointestinal bleeding or peptic ulcer disease
| Precautions | Severe local skin reactions may occur, including erythema, erosion, excoriation, flaking, and edema, which may require discontinuation., Not recommended for use in immunocompromised patients due to unknown efficacy and safety., Avoid exposure to sunlight or artificial UV light (tanning beds) while using ZYCLARA., Use with caution in patients with autoimmune diseases as imiquimod may exacerbate these conditions., Systemic flu-like symptoms (e.g., malaise, fatigue, fever, myalgia) may occur and should be monitored. |
| Food/Dietary | No known food interactions. Avoid grapefruit juice if using concomitant CYP450 metabolized drugs due to potential but minimal interaction. |
Loading safety data…
| Teratogenic Risk | Imiquimod (ZYCLARA) is pregnancy category C. Systemic absorption is minimal following topical application; however, animal studies have shown some fetal effects at high doses. First trimester: Limited data, but risk cannot be excluded; avoid use unless clearly needed. Second and third trimesters: No known specific risks from topical use; may be used if potential benefit justifies potential risk. |
| Fetal Monitoring | No specific fetal monitoring is required for maternal use of topical imiquimod. Monitor maternal application site for local skin reactions. In case of systemic side effects (rare), monitor accordingly. |
| Fertility Effects | No known effects on human fertility from topical use. Animal studies at high systemic doses showed some impairment of fertility; however, minimal systemic absorption with topical application suggests negligible impact. |
| Clinical Pearls | Imiquimod 5% cream applied 5 times per week for up to 16 weeks for superficial basal cell carcinoma. Avoid application on broken or irritated skin. Monitor for local skin reactions including erythema, erosion, and scabbing. Do not occlude with bandages unless specifically instructed. Use only on lesions <2 cm in diameter. |
| Patient Advice | Apply to clean dry skin at bedtime and leave on for approximately 8 hours then wash off with mild soap and water. · Do not use more than prescribed or for longer than directed. · Avoid sexual contact if cream is applied to genital or perianal area due to potential irritation of partner. · Common side effects include redness, swelling, itching, burning, and flaking at application site. · Contact healthcare provider if severe reactions occur such as blisters or ulceration. · Use sunscreen and protective clothing as skin may be more sensitive to sunlight during treatment. |