6. Concurrently using any medication or device which might interfere with the study medication (including RP therapies, drugs used for hypertension, arrhythmia, depression, and pain), specifically calcium channel blockers and the compounds listed in prohibited concomitant medications beyond screening, unless such medication is required for a condition other than Raynaud's. Subjects may participate in the study once these drugs have been discontinued for at least 5 half-lives.