EFFECTS OF SYSTEMIC ISOTRETINOIN ON SERUM MARKERS OF COLLAGEN-SYNTHESIS AND DEGRADATION

In the present investigation, collagen synthesis and degradation were studied by measuring the carboxyterminal propeptide of type I procolla gen (PICP), the aminoterminal propeptide of type III procollagen (PIII NP) and a type I collagen-specific degradation peptide (ICTP) in the s era of 43 male patients, treated for acne with isotretinoin or with te tracycline. The values were compared with those observed in 24 acne pa tients without treatment and in healthy controls. The treatment with i sotretinoin did not seem to affect these parameters in a cross-section al setting, whereas tetracycline treatment was associated with slightl y decreased levels of ICTP. Since there were marked variations in the PICP, PIIINP and ICTP levels between individual subjects, a follow-up study, including male and female patients, others than in the first pa rt of the study, was conducted. Two other biochemical markers of bone metabolism, osteocalcin, reflecting osteoblastic activity, and tartrat e-resistant acid phosphatase (TRAP), reflecting osteoclastic activity, were also analyzed. In females, all these parameters were lower than in males. In addition, the changes in females were more pronounced; in particular, PIIINP and TRAP were significantly increased in females d uring retinoid treatment (p < 0.05 and p < 0.01, respectively). Import antly, no increase was found in the synthesis of type I collagen durin g retinoid treatment, suggesting that the commonly used retinoid dosag es do not stimulate the synthesis of type I collagen in vivo.