This randomized clinical trial studies levocarnitine in treating patients with vismodegib-associated muscle spasms. Levocarnitine may decrease muscle spasms caused by vismodegib.

PRIMARY OBJECTIVES:

I. To determine the effect of levocarnitine on muscle spasm frequency compared to placebo (median percentage comparison)

SECONDARY OBJECTIVES:

I. To assess intensity of muscle spasms after levocarnitine compared to placebo.

II. To assess responses related to activities of daily living or psychosocial function after levocarnitine compared to placebo.

III. To assess the number of body locations affected by muscle spasms after levocarnitine or placebo.

IV. To assess the frequency and severity of all adverse effects on levocarnitine versus placebo.

OUTLINE: Patients are randomized to 1 of 2 treatment arms.

ARM I: Patients receive levocarnitine orally (PO) twice daily (BID) during weeks 1-4. Washout is from weeks 5-8. Patients then cross-over to placebo PO twice daipy for weeks 9-12.

ARM II: Patients receive placebo PO twice daily during weeks 1-4. Washout is from weeks 5-8. Patients then cross-over to levocarnitine for weeks 9-12.

Inclusion Criteria:

• Taking vismodegib daily
• Subject answers item #1 of muscle spasms questionnaire as moderate or severe intensity at time of screening
• At least one muscle spasm per day at time of screening
• Muscle spasms onset after starting vismodegib
• Willing and able to understand and sign consent form

Exclusion Criteria:

• Presence of muscle spasms or active neurologic disease prior to start of vismodegib
• Use of thyroid medication at the time of screening
• Use of Coumadin or acenocoumarol at time of screening
• Change in regimen of muscle relaxant medications within four weeks of enrollment
• If on stable muscle relaxant medication regimen for 4 weeks prior to enrolling, not willing to maintain muscle relaxant regimen without change during course of the study
• Presence of significant renal disease or hemodialysis which would result in dramatic reductions of systemic levocarnitine levels
• History of seizures
• Known deficiency in carnitine (genetic, etc.)
• Any uncontrolled medical condition which may place the patient at increased risk during study participation (at the discretion of the clinical investigator)
• Unable or unwilling to comply with study procedures
• Pregnant or lactating
• All female patients of childbearing potential including those who are within 1 year of last menstrual period will be required to take a pregnancy test during screening, enrollment and at week 0, 4, 8 and 12
• If female of reproductive age, or male partner of female of reproductive age, unwilling to use two medically reliable forms of birth control while on vismodegib
• Unwilling to refrain from donation of bodily fluid (blood, platelets, etc.) within 7 months of last vismodegib dose