Abstract
Objective
To evaluate the evidence for the use of carnitine supplementation in improving walking
performance among individuals with intermittent claudication.
Design
Systematic review.
Methods
An electronic search of the literature was performed using MEDLINE (PubMed), Scopus,
Cochrane Central Register of Controlled Trials and The Cochrane Library from inception
through to November 2012. Search terms included peripheral arterial disease, intermittent
claudication and carnitine. Reference lists of review articles and primary studies
were also examined. Full reports of published experimental studies including randomized
controlled trials and pre-test/post-test trials were selected for inclusion. A quality
assessment was undertaken according to the Jadad scale.
Results
A total of 40 articles were retrieved, of which 23 did not meet the inclusion criteria.
The 17 included articles reported on a total of 18 experimental studies of carnitine
supplementation (5 pre-test/post-test; 8 parallel RCT; 5 cross-over RCT) for improving
walking performance in adults with intermittent claudication. For pre-test/post-test
studies, 300–2000 mg propionyl-l-carnitine (PLC) was administered orally or intravenously for a maximum of 90 days
(7–42 participants) with statistically significant improvements of between 74 m and
157 m in pain free walking distance and between 71 m and 135 m in maximal walking
distance across 3 out of 5 studies. Similarly, PLC (600 mg-3000 mg) was administered
orally in 7 out of 8 parallel RCTs (22–485 participants), the longest duration being
12 months. All but one of the smallest trials demonstrated statistically significant
improvements in walking performance between 31 and 54 m greater than placebo for pain
free walking distance and between 9 and 86 m greater than placebo for maximal walking
distance. A double-blind parallel RCT of cilostazol plus 2000 mg oral l-carnitine or placebo for 180 days (145 participants) did not demonstrate any significant
improvement in walking performance. Of 5 cross-over RCTs (8–20 participants), 4 demonstrated
significant improvements in walking performance following administration of 300–6000 mg
l-carnitine or PLC. Compared to placebo, pain free walking distance and maximal walking
distance improved by 23–132 m and 104 m respectively following carnitine intervention.
Conclusions
Most trials demonstrated a small or modest improvement in walking performance with
administration of PLC or l-carnitine. These findings were largely independent of level or quality of evidence,
while there was some evidence that intravenous administration was more effective than
oral administration and those with severe claudication may achieve greater benefits
than those with moderate claudication. Routine carnitine supplementation in the form
of PLC may therefore be a useful adjunct therapy for management of intermittent claudication.
Further research is warranted to determine the optimal form, duration, dose and safety
of carnitine supplementation across the spectrum of peripheral arterial disease severity
and its effect with concurrent supervised exercise programs and best medical therapy.
These studies should be supplemented with cost effectiveness studies to ensure that
the return on the investment is acceptable.
Keywords
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Article Info
Publication History
Published online: April 03, 2013
Accepted:
March 6,
2013
Received in revised form:
March 6,
2013
Received:
December 14,
2012
Identification
Copyright
© 2013 Published by Elsevier Inc. All rights reserved.
