If you are worried about a possible overdose, I would recommend getting one of those pill boxes with the days of the week on. You can fill one up for him week at a time and you can visually keep track of the pills he is taking.

I have found the below for you:

Overdosing on Sinemet CR: An Introduction
Sinemet® CR (carbidopa-levodopa CR) is a prescription drug usually used to treat Parkinson’s disease. As with any medication, it is possible to take too much Sinemet CR. The specific effects of a Sinemet CR overdose may vary, depending on a number of factors, including the dosage and whether it was taken with any other medications or substances.

Symptoms of a Sinemet CR Overdose
In cases of an overdose with levodopa (one of the components of Sinemet CR), the following symptoms were reported:

* Involuntary body movements
* Nausea and vomiting
* Rapid heart rate (tachycardia)
* Confusion or agitation
* Insomnia and restlessness
* Low blood pressure (hypotension) or high blood pressure (hypertension).

It is expected that Sinemet CR will cause similar overdose symptoms, compared to just levodopa.

Treatment for a Sinemet CR Overdose
The treatment for a Sinemet CR overdose may also vary, and there is no known antidote. If the overdose was recent, a healthcare provider may "pump the stomach" or administer certain medications to induce vomiting. Treatment may also involve supportive care, which consists of treating the symptoms that occur as a result of the overdose. For example, supportive treatment options for a Sinemet CR overdose may include:

* Careful monitoring of the heart, blood pressure, and breathing
* Fluids through an intravenous line (IV)
* Other treatments based on the complications that occur.

It is important that you seek medical attention immediately if you believe that you may have overdosed on Sinemet CR.