Why can't half a tablet of a sustained-release tablet be taken?

In general, sustained-release tablets should not be taken in half because some of these tablets have only one protective membrane that slowly releases the medication to the outside, ensuring a steady and prolonged drug effect. If split, the tablet may lose its sustained-release or enteric-coated properties.

Sustained-release tablets are designed to prolong the release and absorption of medication in the body through specific methods, thereby extending the duration of drug action. In some cases, this is achieved by a sustained-release coating on the tablet or capsule. Taking half a tablet may damage this coating, causing the drug to be released too quickly, shortening its effective duration, and potentially compromising therapeutic outcomes.

However, due to differences in manufacturing techniques, certain sustained-release tablets can be safely split. These tablets typically have a groove on the surface, allowing them to be divided along the line without affecting the sustained-release effect. Splitting such tablets enables more precise dosage adjustment—for example, medications like Betaloc (metoprolol).

It is recommended to follow the instructions provided in the drug's package insert or your doctor's prescription. Do not split or alter the dosage without medical advice to avoid interfering with the drug's intended effect.