Enzymes

Many drugs have enzymes as drug target. On the one hand, a drug can be a substrate for an enzyme and be biotransformed into another substance.

Examples:

On the other hand, a drug can bind an enzyme (without acting as a substrate), resulting in an altered enzyme activity. In this case an enzyme is a receptor.

Examples:

Examples of drugs that inhibit enzymes are ACE-inhibitors, methotrexate, thionamides, and oral anticoagulants.