Recently it was demonstrated that imiquimod in addition to exerting a repairing effect in pre malignant and malignant lesions caused by UV radiation it reverses histopathological changes associated with the photoaging skin.

This is an experimental exploratory study. It included 17 patients. The patients were diagnosed with photoaging grades III and IV in the scale of Glogau and volunteered to participate in the study. Patients were treated with imiquimod 5% topically, for a time period of 12 weeks. Biopsies were taken from periorbital skin area at baseline and after 4 weeks after completing the treatment. Adverse effects, adherence to therapy and patients' satisfaction were measured.

Clinical and histological parameters of photoaging were studied at baseline and after treatment. After completion of treatment with imiquimod, the final clinical evaluation was compared to the initial one.

An experimental study was conducted between July and November 2010 in order to evaluate the efficacy and safety of imiquimod as a treatment option for photoaging.

The sample population was made up of individuals from both genders, older than 40 years, who worked at a flower growing farm located in a rural area of Rionegro (Antioquia) with an altitude of 2,125 meters above sea level; approximately composed of 80 people.

The sample size was calculated considering improvements in 50% or more of patients had to be detected, with a confidence interval of 95%, a power of 80%, a sampling error of 5%.

There were five visits: one at baseline and at months 1, 2, 3 and 4. In each visit patients were assesed clinically, a photograph was taken and adherence and side effects were investigated. Treatment was given during the first 3 months. A biopsy was taken at baseline and during the 4th month assessment. The last visit for clinical monitoring, photographic follow up and skin biopsy was at 16 weeks (4 weeks after discontinuation of the medication). In this last visit patient's satisfaction was evaluated through a survey.

The clinical assessment of photodamage performed by two dermatologists independently included: Changes in texture: dryness/roughness; changes in color: mottled hyperpigmentation, lentigines, yellowing; wrinkles: fine, deep wrinkles and laxity; telangiectasias.

Clinical signs like dryness, burning, erythema, itching, fissures and scabs were used to measure skin irritation.

Severity for the parameters measured in the clinical assessment of photoaging and the assessment of skin irritation was graded on a point scale of 0-3 where 0 was absence, one was mild, 2 moderate and 3 severe.

Biopsies were taken from sites adjacent to the temporal facial area. Aseptic iodine solution was used on the selected area, then the biopsy site was infiltrated with lidocaine 2% (about 0.5 cc) with a short 30-gauge needle and once analgesia was obtained a punch biopsy number 4 mm was taken. The skin biopsy was kept in a jar with formalin properly labeled and sent for histopathology. Then the biopsy site was sutured with 5-0 prolene. The biopsies were sent to the pathology department of the CES University for hematoxylin-eosin staining and they were blind - read by two dermatopathologists who evaluated the following parameters: epidermal changes: epidermal thickness, thickness of the granular layer, melanin content, atypia of melanocytes and keratinocytes, dermal-epidermal junction: pigment incontinence; dermis: inflammation, solar elastosis, fibrosis in the papillary dermis and telangiectasia.

Adherence was measured by asking patients in each one of the visits and it was considered excellent when the drug was applied 3 times per week, regular if the patient missed 2-3 applications between visits and poor if he/she missed more than 5 applications.

Inclusion Criteria:

• patients with Fitzpatrick's skin types I to IV, with a photoaging equal to or greater than 3 on the Glogau measuring scale, who had not used systemic retinoids for over four weeks during six months prior to baseline,
• Patients nor had they undergone chemical peels or used exfoliants or applied botulinum toxin or any other abrasive substance on the face six months prior baseline
• patients that had not used topical retinoids or steroids two months prior to baseline
• patients that had not undergone facial rejuvenation surgery 12 months prior to treatment.

Exclusion Criteria:

• pregnant or nursing women
• patients currently being treated with phototherapy
• patients currently being treated with photochemotherapy or whom were scheduled to start
• patients with suspected skin cancer assessed by clinical examination
• patients with dermatological conditions with changes in the texture or color of the skin
• Patients with inflammatory dermatoses, immunological, infectious, or neoplastic skin diseases located in the periocular area since it could interfere with the clinical assessment of photoaging.
• Patients that at the time of inclusion expressed treatment refusal, disinterest or inability to comply with the protocol as well as those with skin types V and VI were not included.