2. Imiquimod is chemically 2-2 methylpropyl-H-imidazoquinolin-4-amine
molecular formula of C14H16N4
an odourless, white to off-white crystalline solid
I
M
I
Q
U
I
M
O
D
Immune
Quinoline derivative
Modulator
3. Pharmacokinetics
• Available as topical formulation (2.5% , 3.75% , 5%)
• Elimination t1/2 : 30 hr
• Systemic absorption is minimal
4. Mechanism of action
Activates immune cells by engaging TLR7 and (to a lesser extent) Toll-like receptor-8 (TLR8) signalling
Activation of nuclear factor-kappa B (NF-κB)
Induces pro-inflammatory cytokines, such as IFNα, tumour necrosis factor (TNFα), interleukin IL-2, IL-6,
IL-8, IL-12
Imiquimod induces an increase in markers for IFN-γ and the interferon inducible gene product 2’5’-
oligoadenylate synthetase at the treatment site
The antiviral activity is indirect through cytokine induction of IFN-alpha
5. Enhances costimulatory marker expression, increase CCR7and improve pDC viability
Interfere with adenosine receptor (AR) signalling pathways, particularly A2A
Receptor-independent reduction of adenylyl cyclase activity augmenting the pro-inflammatory
activity of imiquimod
Infiltrate of tumour-destructive cells (T lymphocytes, dendritic cells and macrophages) at the
superficial basal cell carcinoma lesions
Exert some pro-apoptotic activity against tumour cells
6.
7. Therapeutic guidelines
Occlusive dressings are not recommended
To be applied on external areas only
Usually applied at bedtime and to be washed with soap water next morning
A thin layer to be applied and massaged gently till no longer visible
Avoid external exposure to nasal mucosa ,lip and eyes
8. FDA Approved Indications
Approved for the first time in 1997 for external genital and perianal wart
Other non viral indications
1. Actinic keratosis
2. Superficial BCC(non facial)
9. Off Label Indications
INFECTIOUS NEOPLASTC INFLAMMATORY OTHERS
Non genital wart Bowen disease Granuloma annulare Keloid
Herpes labialis/genitalis Melanoma in situ Morphea Follicular mucinosis
Molluscum contagiosum keratoacanthoma Porokeratosis of mibelli
Leshmaniasis Extramammary Pagets disease
Epidermodysplsia
verruciformis
Kaposi sarcoma
Pyogenic granuloma
11. Contraindications
• Absolute
Known hypersensitivity(benzyl alcohol,paraben)
Children below 12 years
Internal urethral , intravaginal , intracervical and intra rectal
• Relative
Immunosuppression(HIV , post transplant )
Pregnancy ( Cat C) and Lactation
12. CUTANEOUS SIDE EFFECTS NON CUTANEOUS SIDE EFFECTS
Erythema , itching ,pain ,irritation , ulceration Constitutional : fever , nausea , arthalgia ,myalgia
Lupus, psoriasis ,lichen planus , lichen sclerosis FLU like symptoms
Pemphigus and vitiligo like depigmentation Insignificant transient shift of WBCS
Mycosis fungoides like histologic changes Febrile seizure
Eruptive epidermoid cysts Postural hypotension
Erosive pustular dermatosis of scalp Conjunctivitis, neuropathic pain
13. Imiquimod in external genital and peri anal wart
3.75% Imiquimod cream approved by FDA for Actinic Keratoses and Anogenital warts
Two studies comparing 2.5% vs 3.75% with once daily application for 8weeks revealed complete clearance
in 28.3 36.6 of patients
A study of in HIV+patient on HAART treated with 5 Imiquimod thrice a week showed total clearance in 32
of patients at week 16
14. Imiquimod in superficial BCC
Not a first line treatment for any BCC
FDA approved 5% cream for small<2cm non facial superficial BCC once daily 5days/wk for 6-12 wk
Clearance rate reported range from 43 to100 with various dosage frequency
Difficult to evaluate the efficacy of a cancer : 5 yr clearance rate (follow up)
Imiquimod induced scarring and hypopigmentation can mask the residual tumor
15. Improved response rate observed with twice daily application, a higher incidence of local skin
reactions occurred
Subsequently two double- blind randomized controlled trials showed 82% histologic clearance
with a five times weekly application
These studies formed the basis for approving imiquimod as a treatment for truncal/extremity
superficial BCC
Lower clearance rates have been reported with other BCC subtypes as follows: 42–100% for
nodular BCC and 56–63% for infiltrative BCC
16. Imiquimod in Actinic keratoses
Indicated for AKs on scalp and face
5% Imiquimod approved for a treatment area of approx. 25 sqcm on scalp or face (never both
simultaneously)
Duration : twice a wk for 16 wks
After an overnight stay on ,it is to be washed with soap water next morning
Complete clearance rates with thrice a wk have been reported between 45 and 84 cases for 16wk
Imiquimod can be an alternative to other first line topical treatments like 5FU
17. Recently, a new standard in managing patients with AK has been set with the target being the
detection and clearance of clinical and subclinical AK lesions across an entire sun-exposed
field
This concept has centered on using imiquimod 3.75% cream (used daily on two 2-week
treatment cycles that are separated by a 2-week treatment-free interval) and reduction in
lesions from Lmax
This treatment resulted in 92% median percentage reduction in AK lesions with sustained
lesion clearance for at least 1 year and acceptable tolerability profile
18. Conclusion
Effective immune response modifier
Contraindicated in known hypersensitivity children below 12 yr
Better to be avoided in pregnancy and lactation
FDA approved and effective in treatment external genital wart , Actinic keratoses and Superficial BCC
Significant efficacy in a few other dermatoses like keratoacanthoma , follicular mucinosis , granuloma annulare ,
porokeratosis ,Kaposi sarcoma ,etc.
But further evidence based studied needed to explore its potential in a variety of ever expanding dermatoses
Editor's Notes
Randomized vehicle-controlled clinical trials have shown that applying imiquimod 5% cream three times per weekfor up to 16 weeks completely cleared lesions in about
50% of patients. It was well tolerated, and men tended to have lower clearance rates than women, probably related
to the lower keratinization degree and increased moisture of the vulva compared to the penile shaft
Even though surgery is considered first-line treatment for
BCC, many other therapeutic modalities can be used, …. Imiquimod is currently FDA-approved for the treatment
of truncal/extremity small (<2 cm in size) superficial
BCCs.19,20 An initial randomized trial demonstrated
almost 90% histologic clearance rate of superficial BCC
when treated with 5% imiquimod cream daily for
6 weeks
Interventions available for AK include destructive therapies,
topical medications, chemical peels, and photodynamic
Therapy… Isolated lesions can be treated with
cryotherapy or surgery…. multiple lesions benefit
most from field-directed therapies such as topical 5-fluorouracil,
imiquimod, ingenol mebutate, and diclofenac……Head to head comparing imiquimod and 5FU are lacking