Drugs that lack selectivity have limited therapeutic use.

Drugs that lack selectivity indeed have limited therapeutic use primarily because they can interact with multiple receptors or systems within the body, leading to a broader range of effects, many of which may be undesirable. This non-selectivity can result in a higher risk of side effects and adverse reactions, making it challenging to achieve the desired therapeutic outcome without causing harm.

For example, a non-selective cholinergic agent might stimulate not only the desired muscarinic receptors in the target tissues (e.g., the heart or digestive system) but also nicotinic receptors, which could lead to unwanted stimulation of the neuromuscular junction or other sites. This could result in symptoms such as muscle twitching or cardiovascular complications, which could detract from the medication's efficacy for the intended condition.

As a result, while some non-selective drugs can be beneficial in specific situations or for certain conditions, their general applicability in wider therapeutic contexts is often restricted by the potential for these more extensive effects. Thus, this characteristic underscores the importance of selectivity in drug development, aiming to optimize therapeutic benefit while minimizing adverse effects.