A randomized, open‐label, comparative study of oral doxycycline 100 mg vs. 5% topical benzoyl peroxide in the treatment of mild to moderate acne vulgaris

Acne is one of the most common dermatologic conditions seen in medical practice, affecting almost 80–85% of young adults. The pathogenesis of acne is multifactorial, involving seborrhea, microbial proliferation (Propionibacterium acnes), inflammation, and abnormal follicular desquamation.1–5 Benzoyl peroxide has been used since the 1930s and has antibacterial, keratolytic, and comedolytic properties; it is also highly lipophilic.6,7 It comes in varying strengths of 2.5%−10%. Doxycycline is a semisynthetic tetracycline which has also been used to treat patients with moderate cases of acne vulgaris for many years.8 It has antibacterial, anti-inflammatory, and minimal comedolytic properties. Literature guidelines on the treatment of acne mention these two drugs as first-line therapy in the management of mild to moderate acne vulgaris. Oral antibiotics are usually reserved for moderate cases, whereas topical drugs are used for milder cases.1,2,5 Benzoyl peroxide and doxycycline have similar antibacterial and anti-inflammatory properties, but have never been compared with each other as monotherapy in mild to moderate cases of acne vulgaris. The aim of this study was to observe whether oral monotherapy with doxycycline had a superior effect to that produced by topical benzoyl peroxide in the treatment of mild to moderate acne vulgaris. In this randomized, open-label, 16-week trial, 40 patients (14–30 years of age) with mild to moderate acne vulgaris were randomly allocated to two treatment groups (n = 20 per group). Pregnant women and those using estrogen-containing regimens for contraception were excluded. The Research Ethics Committee of the Faculty of Health Sciences, University of Pretoria, approved the study. All patients signed informed consent. Participants received either 100 mg doxycycline orally daily or 5% topical benzoyl peroxide applied twice daily. After 4, 8, 12, and 16 weeks, patients were reviewed to evaluate their progress on treatment using a Global Acne Grading System.9 These global assessments were performed by three family practitioners. The primary efficacy evaluations were lesion reductions from baseline and treatment success. The data were analyzed using Pearson χ2 and Fischer's exact tests. A log-rank test for equality of survivor functions was used to test the differences in outcome for both treatments at the end of 16 weeks. Clinical outcomes were classified into two broad groups of either good or limited improvement. Limited improvement outcome was defined as moderate to no improvement and good outcome was defined as marked improvement to complete acne clearance. At 4, 8, 12, and 16 weeks, doxycycline showed slightly better lesion reductions from baseline compared with benzoyl peroxide. The time taken for good outcomes to be observed was slightly less for doxycycline. There was, however, no statistically significant difference between the two treatment groups. Significant clinical improvements in total acne lesions from baseline were observed in both treatment groups (Fig. 1, Table 1). Kaplan–Meier survival functions: doxycycline group (Doxy) vs. benzoyl peroxide group (B-Per). All active therapies showed significant improvement of acne from baseline (baseline = 1). There was no significant difference between treatment groups The use of oral antibiotics as monotherapy has been criticized by some authors, arguing the development of resistance.3 Antibiotic use has traditionally been reserved for moderate to severe acne cases, and they are usually used in combination with topical agents.3,5 Doxycycline induces a more rapid clinical response than the older first-generation tetracyclines.4 Antibiotic resistance is a problem only when we consider the drug as purely antibacterial. Doxycycline is more than just an antibacterial agent; it inhibits leukocyte chemotaxis and reduces free fatty acid production by inhibiting bacterial lipases.10 These processes are implicated in the pathogenesis of acne vulgaris. These additional properties need to be taken into account when concerns about antibiotic resistance arise. In conclusion, although these findings are interesting, the small numbers do not permit meaningful statistical analysis. The author would like to thank Cipla Medpro (Pty) Ltd for supplying the study drug (Doxitab®) and Drs Malunga and Mzolo for helping with the recruitment of patients. The author would also like to thank Professor J. R. Snyman who was a supervisor for this clinical trial.