What is the defining feature of a gel medication?

The defining feature of a gel medication is that it often consists of water and small particles. Gels are generally semi-solid systems that can include a mixture of a liquid, typically water, with fine solid particles dispersed within it. This characteristic allows gels to maintain their structure while providing a smooth, easily spreadable consistency that can adhere to surfaces, making them suitable for various applications such as topical medications or certain types of systemic drug delivery.

This property of gels allows for effective formulation in the pharmaceutical industry, particularly for delivering medications in a controlled manner. The other options might describe different forms or characteristics of medications, but they do not accurately capture what defines a gel.