Levetiracetam and Muscle Mass
Levetiracetam is not associated with muscle mass loss and is considered a weight-neutral antiepileptic medication. 1, 2
Evidence on Levetiracetam and Weight/Muscle Effects
Levetiracetam belongs to a group of antiepileptic medications that are considered weight-neutral, as clearly stated in clinical guidelines. According to the 2017 practical guidelines for pharmacotherapy:
- Levetiracetam is categorized as a weight-neutral antiepileptic medication, alongside lamotrigine and phenytoin 1
- This contrasts with other antiepileptic medications like gabapentin, pregabalin, and valproic acid, which are consistently associated with weight gain 1
A comprehensive analysis of randomized controlled clinical trials specifically examining levetiracetam's effect on body weight found:
- No significant changes in body weight were observed in patients taking levetiracetam (mean baseline weight: 74.3±16.6 kg; final weight: 74.3±16.6 kg) 2
- Clinically significant weight changes (defined as >7% change from baseline) occurred in only 9% of levetiracetam-treated patients, with equal distribution between weight gain (4.5%) and weight loss (4.5%) 2
- Neither baseline BMI, gender, nor background antiepileptic drugs predisposed patients to significant weight changes 2
Rare Adverse Effects Related to Muscle
While levetiracetam does not typically cause muscle mass loss, there are rare reports of rhabdomyolysis (acute muscle breakdown) associated with its use:
- Case reports have documented rare instances of rhabdomyolysis with levetiracetam use 3, 4
- This serious adverse effect is characterized by elevated creatine phosphokinase (CK) levels and potential kidney damage 3
- The underlying pathophysiology of levetiracetam-induced rhabdomyolysis remains unknown 3
Common Side Effects of Levetiracetam
The most common adverse effects of levetiracetam are:
- CNS-related effects including somnolence (10.5-15.2%), asthenia, headache, dizziness, and fatigue 5, 6, 7
- Behavioral alterations and irritability (occurring in approximately 12-15% of patients) 5, 7
- Gastrointestinal symptoms such as vomiting 7
Clinical Implications and Monitoring
When prescribing levetiracetam:
- No specific monitoring for muscle mass loss is required as this is not a recognized adverse effect 5, 2
- Regular clinical follow-up should focus on the more common CNS and behavioral side effects 5
- If a patient reports unexpected muscle pain, weakness, or dark urine while taking levetiracetam, check CK levels to rule out the rare possibility of rhabdomyolysis 3, 4
Conclusion
Based on the available evidence, levetiracetam is considered weight-neutral and is not associated with muscle mass loss in the vast majority of patients. This favorable metabolic profile makes it an appropriate choice for patients where weight gain would be problematic. The rare reports of rhabdomyolysis should be considered in the context of millions of patients taking this medication safely.