C19H22ClN

C19H22ClN is a chemical compound with the systematic name **N-(4-chlorophenyl)-N-methyl-2-phenylpropan-1-amine**, commonly recognized by its trivial name **chlorphenamine**. It is a first-generation antihistamine primarily used to treat allergic reactions, hay fever, and mild to moderate allergic skin conditions. Chlorphenamine functions by blocking the action of histamine, a substance in the body that is released during allergic reactions, thereby alleviating symptoms such as itching, sneezing, and runny nose.

The compound was first synthesized in the mid-20th century and has since been widely used in pharmaceutical formulations, often in the form of its maleate or hydrochloride salts. Chlorphenamine is available in various dosage forms, including tablets, capsules, syrups, and injectable solutions. It is also commonly found in combination with other medications, such as decongestants or pain relievers, to enhance its therapeutic effects.

Structurally, C19H22ClN consists of a chlorophenyl group attached to a tertiary amine, which contributes to its pharmacological activity. The presence of the chlorine atom influences the compound’s lipophilicity, affecting its ability to cross the blood-brain barrier, a factor that contributes to its sedative side effects, which are more pronounced than those of second-generation antihistamines.

While generally safe when used as directed, chlorphenamine may cause drowsiness, dry mouth, or dizziness in some individuals. Prolonged use or excessive dosage can lead to more serious adverse effects, including cardiac arrhythmias or paradoxical excitation, particularly in children. Due to these risks, chlorphenamine is not recommended for long-term use without medical supervision.

The compound remains a staple in over-the-counter allergy medications, though its use has declined in favor of newer antihistamines that produce fewer sedative effects. It continues to be studied for its potential applications in other therapeutic areas, though no significant developments beyond its established uses have been widely adopted.