Subantimicrobial dose doxycycline as an adjunct to scaling and root planing: post-treatment effects

Background/objective: Subantimicrobial dose doxycycline (SDD 20 mg bid) plu s scaling and root planing (SRP) significantly improved clinical attachment level (CAL) and reduced probing depth (PD) compared with placebo plus SRP in a double-blind, placebo-controlled, multicenter study of patients with a dult periodontitis (AP). In a study conducted as a follow-up, the post-trea tment effects of SDD were assessed in patients who completed the SRP study. Methods: The SRP study was a 9-month, active-treatment study and the follow up was a 3-month, no-treatment study. In the SRP study, tooth sites in qual ifying quadrants were scaled and root planed and patients were randomized t o receive twice daily SDD 20 mg or placebo. In the follow-up, patients rece ived no study drug; investigators and patients remained blinded to the prev ious treatment group assignments. Efficacy measures included the change in CAL and PD from baseline values determined at the start of the SRP study in tooth sites stratified by baseline PD (i.e., 0-3 mm, 4-6 mm, greater than or equal to7 mm). Safety was evaluated using adverse event data and the res ults of clinical laboratory tests, oral pathology examinations, and microbi ological assessments. Results: Within each disease stratum, the incremental improvements in PD an d CAL demonstrated in the SDD group over 9 months of active treatment were maintained through 3 additional months of no treatment. Treatment cessation did not result in an accelerated regression of periodontal health. No diff erences in the incidence of adverse events (including those related to infe ction) or laboratory or microbiological parameters were noted between the S DD group and the placebo group. Conclusions: The administration of SDD 20 mg bid for a period of up to 9 mo nths is not associated with rebound effects or delayed or negative aftereff ects for a 3-month period after cessation of therapy.