Open, prospective, randomized, single-centre study in patients with moderate to severe facial acne vulgaris. Three circular areas with a diameter of 4 cm, each circle including at least 4 inflammatory lesions, will be selected in acne-affected areas in the face. One area should be identified on each cheek and one area should be identified on the forehead. The minimum distance between the three areas should be at least 4 cm. For each patient the three areas will be randomized to either a pre-treatment cleaning using a wipe containing an ethyl alcohol solution(one area) or a cleansing wipe containing saline water (two areas), before application of the Visonac cream. One of the areas cleaned with saline wipe will also be occluded with a transparent dressing (Tegaderm) during the incubation time. In vivo fluorescence spectroscopy will be performed in the three areas before cream application, and at 1h, 1.5h, 2h, 2.5h and 3 h after cream application. After the last fluorescence spectroscopy reading, the cream should be wiped off and the patient should protect the three areas from sunlight, prolonged, or intense light for 2 days.

The study was extended with additionally 8 patients to explore the photoactive porphyrin levels over a 24 hour period:

The patients will clean their face with Cetaphil Gentle Skin Cleanser before cream application. For each patient the three areas will be randomized to Visonac 80mg left on the skin for 24 hours and Visonac (MAL8%) to be wiped of after 1 hour.

In vivo fluorescence spectroscopy will be performed at all three areas before cream application, and at 2h, 3 h, 4h, 5h, 8h, 10h, 11h, 12h, 13h, 15 and 24h after cream application. The exact time points may be adjusted based on the result from the previously included patients. All patients will be instructed to protect the three areas from sunlight, prolonged, or intense light for 2 days.

Inclusion Criteria:

• Signed and verified informed consent form. For patients under age of 18, an assent form in conjunction with an informed consent form, signed and verified by parent/guardian.
• Adolescent and adult female and male patients, from 12 to 35 years of age.
• Patients with moderate to severe facial acne vulgaris according to the IGA scale.
• Female patients who are surgically sterile, pre-menstrual, postmenopausal, abstinent, or willing to use an adequate means of contraception including birth control pills, or barrier methods and spermicide for at least 14 days prior to the study visit.
• Patients with skin type II to III (Fitzpatrick).
• Patients with 3 areas of 4 cm in diameter, each including at least with at least 4 inflammatory lesions (papules, pustules, and nodules) in the face (at cheek and forehead).

Exclusion Criteria:

• Subject is the investigator or any sub investigator, research assistant, pharmacist, study coordinator, other staff or relative thereof directly involved in the conduct of the protocol.
• Patients unlikely to comply with the protocol, e.g. mental condition rendering the patient unable to understand the nature, scope, and possible consequences of the clinical study, uncooperative attitude or unlikelihood of completing the study (e.g. drug or alcohol abuse).
• Female subjects with childbearing potential (i.e. ovulation, pre-menopausal, not surgically sterilized) not willing to use a medically accepted contraceptive regimen while on treatment.
• Pregnancy
• Lactating.
• Participation in other clinical studies either currently or within the last 30 days.
• Patients with porphyria.
• Known allergy to (MAL), to a similar PDT compound, or to excipients of the cream
• Patients with cutaneous photosensitivity.
• Patients that have received topical treatments for their acne within the last 14 days. Medicated cleansers not containing active ingredients such as 5% BPO or high concentration of salicylic acid may be stopped before the treatment. (Cosmetic Cleansers that contains no more than 2 % salicylic acid is allowed).
• Patients that has received oral antibiotics for treatment of their acne within the last month.
• Patients that has received oral isotretinoin within the last 6 months.
• Patients with a beard that might interfere with study assessments.
• Patients with melanoma or dysplastic nevi in the treatment area