Adrenerge agonisten: Chemie en Structuur-Activiteitsrelatie

Structurally, adrenergic agonists are characterized by a fundamental β-phenylethylamine skeleton.

For maximum agonist activity, –OH groups at positions 3 and 4 of the aromatic ring are essential. The absence of one or both –OH groups diminishes potency while enhancing metabolic stability and CNS penetration.

The inclusion of a two-carbon linker between the ring and amino group is essential for optimum agonist activity.

Bulkier alkyl substituents on the amino group generally enhance β but decrease α-agonist activity, with α-selective phenylephrine being an exception.

–CH₃ substitution on the α-carbon improves lipophilicity, reduces metabolic susceptibility to MAO, and extends the duration of action.

Conversely, –OH substitution on the β-carbon lowers lipophilicity and CNS penetration but enhances both α- and β-agonist activity.

In conclusion, structural modifications of the β-phenylethylamine skeleton yield agonists with varying adrenoceptor affinities, distinct pharmacokinetic profiles, and differing bioavailability.