IN THE UK AND A NUMBER OF OTHER COUNTRIES THE INITIAL ORAL DOSE OF ISOTRETINOIN FOR ACNE IN ADULTS AND ADOLESCENTS FROM 12 YEARS OF AGE IS 500 MICROGRAMS/KG DAILY, ALTHOUGH IN THE USA INITIAL DOSES OF UP TO 1 MG/KG DAILY ARE PERMITTED. THE DOSE IS GIVEN WITH FOOD ONCE DAILY OR IN TWO DIVIDED DOSES AND ADJUSTED IF NECESSARY UP TO 1 MG/KG DAILY ACCORDING TO RESPONSE AND ADVERSE EFFECTS. PATIENTS INTOLERANT TO THE INITIAL DOSE MAY BE ABLE TO CONTINUE TREATMENT AT A LOWER DOSE, BUT THERE IS A HIGHER RISK OF RELAPSE. DOSES UP TO 2 MG/KG DAILY ARE PERMITTED IN THE USA AND SOME OTHER COUNTRIES FOR PATIENTS WHOSE DISEASE IS VERY SEVERE OR PRIMARILY ON THE BODY INSTEAD OF THE FACE. A LOWER STARTING DOSE HAS BEEN RECOMMENDED IN THE UK FOR PATIENTS WITH SEVERE RENAL IMPAIRMENT .
ACUTE EXACERBATION OF ACNE IS OCCASIONALLY SEEN DURING THE INITIAL PERIOD, BUT USUALLY SUBSIDES WITHIN 7 TO 10 DAYS ON CONTINUED TREATMENT. TREATMENT SHOULD CONTINUE FOR 15 TO 24 WEEKS OR UNTIL THE TOTAL CYST COUNT HAS DECREASED BY OVER 70%. LONG-TERM REMISSION AND RELAPSE RATES ARE RELATED TO TOTAL DOSE, AND ADDITIONAL BENEFIT IS NOT EXPECTED BEYOND A CUMULATIVE DOSE OF 120 TO 150 MG/KG. IMPROVEMENT MAY CONTINUE FOR SEVERAL MONTHS AFTER CESSATION OF TREATMENT; PROLONGED REMISSIONS CAN OCCUR.
REPEAT COURSES ARE NOT NORMALLY RECOMMENDED BUT OCCASIONALLY THEY MAY BE REQUIRED. HOWEVER, SINCE ACNE MAY CONTINUE TO IMPROVE AFTER STOPPING ISOTRETINOIN, THERE MUST BE AT LEAST A 2-MONTH DRUG-FREE PERIOD BEFORE STARTING REPEAT TREATMENT.
FOR THE TOPICAL TREATMENT OF ACNE A GEL CONTAINING 0.05% OF ISOTRETINOIN IS APPLIED SPARINGLY ONCE OR TWICE DAILY. A THERAPEUTIC RESPONSE MAY NOT BE EVIDENT FOR 6 TO 8 WEEKS.