In Situ Activation of Microencapsulated Drugs

In a new method of delivering drugs to target sites in a human body, (1) the drugs would be stored in inactive forms in timed-release microcapsules that would be injected, then (2) the drugs would be activated by exposing the target sites to suitable forms of penetrating energy that could include electromagnetic radiation (radio waves, light, or x rays), ultrasound, or heat, then (3) the drugs would diffuse out of the microcapsules. The method would be well suited for drugs that have short shelf lives in their active forms and/or could be activated at target sites upon exposure to nonharmful activation energy.