Low-dose baclofen therapy raised plasma insulin-like growth factor-1 concentrations, but not into the normal range in a predictable and sustained manner in men with chronic spinal cord injury

Abstract

Objective

To evaluate, whether once-daily oral baclofen administration increases and/or sustains plasma insulin-like growth factor-1 (IGF-1) concentration in 11 men with chronic spinal cord injury (SCI) and IGF-1 deficiency (i.e. <250 ng/ml).

Design

Prospective, open-label, dose titration study. Baclofen was administered at 20 mg/day for 8 weeks; then increased to 40 mg/day for another 8 weeks. Plasma IGF-1 and self-reported side effects were measured at baseline and every other week for the duration of the study.

Results

The subjects were 43 ± 12 years old, had duration of injury of 20 ± 12 years; eight subjects had a complete motor injury, and eight had paraplegia. Nine of 11 subjects completed the 20 mg/day treatment and 5 subjects completed the 40 mg/day treatment. Plasma IGF-1 levels improved with each baclofen dose; however, only one subject increased from baseline and remained above the targeted physiological range of 250 ng/ml throughout treatment. A significant increase in IGF-1concentration was observed between baseline and week 2 (154 ± 63 vs. 217 ± 69 ng/ml; P < 0.05), weeks 8 and 10 (188 ± 95 vs. 228 ± 93 ng/ml; P < 0.05), and weeks 8 and 16 (188 ± 95 vs. 259 ± 92 ng/ml; P < 0.05). No serious side effects were observed at 20 mg/day; the 40 mg/day dose was less well tolerated.

Conclusion

Baclofen was not effective at sustaining plasma IGF-1 concentrations in the physiological range in men with chronic SCI.

Keywords:

• Baclofen
• Gamma-aminobutyric acid
• Insulin-like growth factor-1
• Testosterone
• Spinal cord injuries
• Paraplegia
• Tetraplegia
• Spasticity

Acknowledgements

The authors thank the James J. Peters VA Medical Center, Bronx, NY, the Department of Veterans Affairs Rehabilitation Research & Development Service, and Kessler Institute for Rehabilitation, West Orange, NJ for their support. This work was funded by the Veteran Affairs Rehabilitation Research & Development National Center of Excellence for the Medical Consequences of Spinal Cord Injury (No.'s B4162-C & B9212-C).