Isotretinoin Treatment in Patients With Acne Vulgaris: Does It Impact Muscle Strength, Fatigue, and Endurance?
The objective of this study was to evaluate the effects of isotretinoin on muscle strength, fatigue, and endurance in patients with acne vulgaris. The study included 27 patients with acne vulgaris who underwent treatment with isotretinoin as well as 26 control patients for comparison. Participants in the treatment group received oral isotretinoin 0.5 mg/kg once daily for 1 month followed by an increased dose of 1 mg/kg once daily for 2 months. Isokinetic measurements were obtained from the hamstrings and quadriceps on the nondominant side of the body at baseline and 3-month follow-up using an isokinetic dynamometer. Results indicated that systemic isotretinoin did not significantly alter muscle strength, fatigue, and endurance.
- Musculoskeletal adverse effects have been reported due to isotretinoin treatment.
- This study investigated the effects of isotretinoin on muscle strength, fatigue, and endurance in patients with acne vulgaris using an isokinetic dynamometer.
- Systemic isotretinoin treatment did not alter muscle strength, fatigue, or endurance.
Muscles mainly consist of type I (slow oxidative), type IIA (fast oxidative), and type IIB (fast glycolytic) muscle fibers. Type I fibers produce low force and high endurance, type IIB fibers produce high force and low endurance, and type IIA fibers fall in between the two. At low AVs (eg, 60° per second), only type II fibers contract. As the AV increases (eg, 180° per second), only type II fibers contract. Consequently, the observation of a decrease in the isokinetic test parameters at low or high AVs indicate the decrease in type I or type II contracting muscle fibers.11,12 In our study, the isokinetic values did not significantly change. As such, we concluded that isotretinoin treatment did not result in the reduction of muscle fibers in our patient population.
The H:Q ratio is the indicator of muscle balance and dynamic stabilization of the knee. It is calculated by dividing the PT of the hamstrings by the PT of the quadriceps in concentric motion.13 Additionally, muscle fatigue demonstrates the endurance of the contraction of type IIB fibers (anaerobic).14 In our study, isotretinoin treatment did not impact the H:Q ratio or muscle fatigue.
This study included a few important limitations. The sample size was small, particularly concerning the number of participants who reported myalgia. The lack of laboratory evaluations (eg, creatinine kinase) also was a limitation. Finally, the short study period limited the conclusions that could be drawn from the data.
Conclusion
Results from the current study revealed that systemic isotretinoin treatment did not alter muscle strength, fatigue, or endurance. Further studies taking into account histologic evaluations with larger sample sizes and long-term follow-up are needed.
