What type of drugs stimulate a receptor into action?

When discussing drugs that stimulate a receptor into action, the term that best fits is "agonist." Agonists are compounds that bind to specific receptors and activate them, which leads to a biological response. This activation can result in various effects depending on the type of receptor and the tissues involved.

For example, if an agonist binds to a receptor for a neurotransmitter, it can enhance or mimic the physiological effects that the neurotransmitter would typically produce. This property is crucial in pharmacology, as agonists can be used therapeutically to treat various conditions by promoting desired responses in the body.

In contrast, antagonists block or inhibit the action of receptors, preventing the natural ligand (like a neurotransmitter or hormone) from activating the receptor. Analgesics refer to pain-relieving medications without specifically indicating their mechanism of action on receptors. Inhibitors generally refer to substances that decrease or prevent a specific biological activity but do not necessarily imply receptor activation. Therefore, an agonist is the most accurate choice for describing drugs that stimulate receptors.