Yes, if you take a 20 mg tablet and cut it into two equal parts, each half tablet will be approximately equal to 10 mg. This is because the division is done equally, resulting in two pieces with half the original dose each.
When a medication or substance is distributed uniformly within a tablet, cutting it in half should theoretically provide two equal parts. In this case, the tablet's total mass is divided into two equal portions, and since the distribution of the active ingredient is uniform, each half will contain roughly the same amount of the active ingredient.
However, it's important to note that while this approximation is generally true for many medications and substances, it may not be precise in all cases. Some tablets are designed to release the active ingredient over time, have a protective coating, or have specific formulations that ensure proper dosage. Cutting such tablets might alter their intended release profile or create uneven dosages, leading to potential health risks.
To be absolutely sure about the safety and effectiveness of splitting a tablet, it's best to consult with a healthcare professional or pharmacist. They can provide guidance based on the specific medication you are taking and advise on whether splitting the tablet is a safe and appropriate option. In some cases, they might recommend alternative dosing forms or strengths that are already available and approved by the manufacturer for appropriate dosage adjustments.