INTRODUCTION:It is the dextrorotary stereoisomer of the amphetamine molecule, which can take two different forms. It is a slightly polar, weak base and is lipophilic in nature.
This compound belongs to the class of organic compounds known as amphetamines and derivatives. These are organic compounds containing or derived from 1-phenylpropan-2-amine
PHARMACODYNAMICS: These are sympathomimetic amines with CNS stimulant activity.
Peripheral actions :- elevations of systolic and diastolic blood pressures and weak bronchodilator and respiratory stimulant action.
MECHANISM OF ACTION:
* Dextroamphetamine stimulates the release of norepinephrine from central adrenergic receptors.
* At higher dosages, it causes release of dopamine from the mesocorticolimbic system and the nigrostriatal dopamine systems by reversal of the monoamine transporters.
* Dextroamphetamine may also act as a direct agonist on central 5-HT receptors and may inhibit monoamine oxidase (MAO).
* In the periphery, amphetamines are believed to cause the release of noradrenaline by acting on the adrenergic nerve terminals and alpha- and beta-receptors.
* Modulation of serotonergic pathways may contribute to the calming affect.
HALF LIFE :-
10-28 hours
OVERDOSE /TOXICITY SYMPTOMS :
* Restlessness
* Tremor
* Rapid respiration
* Confusion
* Hallucinations
* Fatigue and depression
* Cardiovascular effects include arrhythmias, hypertension or hypotension, and circulatory collapse.
* Gastrointestinal symptoms include nausea, vomiting, diarrhea, and abdominal cramps.
THERAPEUTIC USES :
* Dexamphetamine is a central nervous system stimulant
* It is prescribed for the treatment of attention deficit hyperactivity disorder and narcolepsy.
* It is also used as an athletic performance and cognitive enhancer
* Dexamphetamine is also widely used by military air forces as a 'go-pill' during fatigue-inducing mission profiles such as night-time bombing missions.
* Preparations containing dexamphetamine were also used in world war 2 as a treatment against fatigue.
SIDE EFFECTS :
* nausea vomiting or abdominal pain.
* headache.
* dizziness.
* mood changes such as depression or irritability.
* tremor or palpitations.
* restlessness, nervousness or insomnia.
* loss of appetite, weight loss or slower growth in children.
DRUG - DRUG INTERACTIONS :-
* ACEBUTOLOL +DEXAMPHETAMINE= Severe risks of side effects.
* ACEPROMAZINE+ DEXAMPHETAMINE=Decreased effect of dexamphetamine.
* ACETAZOLAMIDE+ DEXAMPHETAMINE = Decreased excretion rate of Dexamphetamine
* ACETOPHENAZINE+ DEXAMPHETAMINE=Decreased stimulatory activities of Dexamphetamine.
* ALUMINIUM HYDROXIDE+ DEXAMPHETAMINE=Decreased excretion rate of Dexamphetamine .
* AMMONIUM CHLORIDE+ DEXAMPHETAMINE =Decreased serum concentration of dexamphetamine.
CONTRAINDICATIONS :
* Advanced arteriosclerosis, symptomatic cardiovascular disease, moderate to severe hypertension, hyperthyroidism, known hypersensitivity or idiosyncrasy to the sympathomimetic amines, glaucoma.
* Agitated states
* Patients with a history of drug abuse
* During or within 14 days following the administration of monoamine oxidase inhibitors (hypertensive crises may result).
REFERENCES: Tripathi K.D, "Essentials of medical pharmacology", Edition 7th, page no-134,135
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