Functional groups and drug classes
Practice questions with explanations

C. Indole derivatives resembling serotonin, allowing selective binding to 5-HT1B and 5-HT1D receptors

Their design as selective serotonin receptor agonists improved on the ergot alkaloids, which act at many receptors and cause more vasoconstriction and adverse effects. Differences between triptans in lipophilicity and half-life explain variations in onset, duration and recurrence rates, so a patient who fails one may respond to another.

D. Corticosteroids, based on the four-ring cyclopentanoperhydrophenanthrene nucleus

The steroid nucleus is shared by glucocorticoids, mineralocorticoids, sex hormones and vitamin D, and small substitutions shift the balance between glucocorticoid and mineralocorticoid effect. Prednisolone has less mineralocorticoid activity than hydrocortisone, and dexamethasone essentially none, which is why dexamethasone causes less sodium and fluid retention.

D. Biphenyl tetrazole derivatives that mimic part of the angiotensin II structure to block the AT1 receptor

The tetrazole ring is a bioisostere of a carboxylic acid, offering similar acidity and shape with better metabolic stability and lipophilicity. It allows the molecule to occupy the angiotensin binding site as an antagonist. The design illustrates rational medicinal chemistry: mimic the natural ligand's key contacts while avoiding activation.