Stimulants

Stimulants

Stimulants are used to treat attention deficit hyperactivity disor-der (ADHD), a condition characterized by inattention, impulsivity, and hyperactivity. They include:

·                 dextroamphetamine

·                 lisdexamfetamine

·                 methylphenidate

·                 mixed amphetamine salts

·                 modafinil.

Pharmacokinetics

Stimulants are well absorbed from the GI tract and are distributed widely in the body. Methylphenidate undergoes significant first pass effect.

Metabolism and excretion

Stimulants are metabolized in the liver and excreted primarily in urine.

Pharmacodynamics

These drugs are believed to work by increasing levels of dopa-mine and norepinephrine in one of three ways: by blocking the reuptake of dopamine and norepinephrine, by enhancing the presynaptic release, or by inhibiting MAO.

Pharmacotherapeutics

Stimulants are the treatment of choice for ADHD. They’re help-ful in improving attention, leading to improved school or work performance, and decreasing impulsivity and hyperactivity, if present. Pemoline, however, is no longer a first line choice for treatment of ADHD because it can cause hepatotoxicity.

Dextroamphetamine and methylphenidate are also used in the treatment of narcolepsy.

Drug interactions

Methylphenidate may decrease the effect of guanethidine and may increase the effects of TCAs, warfarin, and some anticonvul-sant drugs.

Stimulants shouldn’t be used within 14 days of discontinuing therapy with an MAOI.

Stimulants are highly abused substances, and close monitoring is required. (See Adverse reactions to stimulants.)