Controlled drug delivery is a simpler and more convenient way to slowly release drugs than taking low-dose pills or injections at frequent intervals. Additionally, it also lowers the risk of incorrect dosage.
Zaffaroni invented controlled (slow) release drugs, mimicking the way the body releases hormones. Eventually, he created many pharma companies that went on to sell various slow-release drugs.
Zaffaroni improved his slow drug delivery by inventing the transdermal patch, founding a company ALZA for that innovation alone. Significantly, in 2001, ALZA sold to Johnson & Johnson for $10 billion.
Other Zaffaroni controlled drug delivery use cases include drugs to treat glaucoma, non-insulin dependent diabetes, chronic pain, nausea and motion sickness, and nicotine addiction. A skin patch, that looks like adhesive tape, delivers the drugs.