Sinemet CR Carbidopa; Levodopa sustained-release tablets What do carbidopa-levodopa sustained-release tablets do?CARBIDOPA-LEVODOPA (Sinemet(R) CR) is used to treat Parkinson’s disease. Levodopa can help correct an imbalance of chemicals in the brain caused by Parkinson’s disease. Levodopa will not cure Parkinson’s disease, but will help to control the symptoms. Carbidopa helps levodopa work better, and this can decrease some side effects, such as nausea. Sustained-release tablets slowly release the medicine over 4 to 6 hours. Generic carbidopa-levodopa sustained-release tablets are available.