Sympathomimetic drug disorder

Older adults, in particular, are at risk for exacerbation of existing disorders such as hypertension, tachycardia, or arrhythmias if systemic absorption of sympathomimetic ophthalmic drugs occurs... 

These drugs are best avoided in patients with cerebrovascular, cardiovascular and hepatic disorders. Some sympathomimetic effects may occur, mainly mild tremor and occasionally cardiac arrhythmias. Apparent anticholinergic effects may also occur but these are the result of sympathetic potentiation in tissues with dual cholinergic/adrenergic innervation, e.g. pupil. Sympatholytic effects can also occur, principally postural hypotension, because of synthesis of relatively inactive false transmitters, e.g. octopamine, in nerve terminals following inhibition of MAO and activation of alternative metabolic pathways. 

Dexamphetamine is one of the most powerful and best known psychomotor stimulants, and other similar agents include dexfenfluramine. diethylpropion and fenfluramine. All these are on the controlled drugs list, and have a limited medical use as appetite suppressants. Such drugs work by interacting with the release of monoamines within the central (and peripheral) nervous system, and can be regarded as indirect SYMPATHOMIMEtics. Recently, there has been some use of the weak amphetamine-like stimulant methylphenidate to treat attention-deficient hyperactivity disorder (ADHD) in children. 

Amphetamine and methamphetamine (Figure 34-19) are CNS stimulant drugs that have limited legitimate pharmacological use. ° They are used to treat narcolepsy, obesity, and attention-deficit hyperactivity disorders. However, they produce an initial euphoria and have a high abuse potential. Other sympathomimetic amines that also have high potential for abuse include the designer amphetamines, ephedrine, pseudoephedrine, phenylpropanolamine, and methylphenidate (Ritalin). 

Epinephrine, the sympathomimetic adrenal hormone, is found to act on smooth muscles, heart and the gland eells thereby causing a similar pattern of actions as may have been produced by the stimulation of the respective adrenergic nerves. Hence, it had been invariably used to stimulate the heart, enhances the heart rate, tones up the blood pressure and above all affords relaxation of the musculature of the intestine and bronchi. It is usually the drug of choice in acute allergic disorders and histamine reaetions. 

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