Soft drug

Soft drug is a term used in pharmacology to describe drugs that are designed to be metabolically unstable, so they can be quickly eliminated from the body after they have exerted their effect. This is in contrast to hard drugs, which are metabolically stable and remain in the body for a longer period of time.

Definition

The term "soft drug" was first coined by medicinal chemist Corwin Hansch. According to Hansch, a soft drug is "an active drug that undergoes a predictable and controllable metabolic deactivation in vivo to a non-toxic and inactive product after it has achieved its desired effect." This is done to minimize the potential for harmful side effects and drug accumulation in the body.

Examples

Examples of soft drugs include loteprednol, a corticosteroid used in eye drops to treat inflammation; and remifentanil, an ultra-short-acting synthetic opioid used for pain relief and sedation. Both of these drugs are designed to be quickly metabolized and eliminated from the body to minimize side effects.

Soft drugs vs Hard drugs

The main difference between soft drugs and hard drugs is their metabolic stability. Soft drugs are designed to be metabolically unstable, meaning they are quickly broken down and eliminated from the body. This can help to minimize side effects and prevent drug accumulation, which can be particularly beneficial in patients with impaired kidney or liver function.

On the other hand, hard drugs are metabolically stable and remain in the body for a longer period of time. This can lead to a longer duration of action, but it can also increase the risk of side effects and drug accumulation.

See also

• Prodrug
• Drug design
• Pharmacokinetics
• Pharmacodynamics