Pharmacology and Pharmacokinetics
Caffeine is produced naturally in many plants, but may also be artificially manufactured. Caffeine is found in many plants such as guarana, cacao pod, and cola nut. Chemically, it is a methylxanthine, a family that includes theophylline and theobromine. Methylxanthines cause the release of catecholamines, stimulating β1 and β2 adenosine receptors; blocking the inhibitory neurotransmitter adenosine, and inhibiting phosphodiesterase, resulting in increased intracellular cyclic adenosine monophosphate (cAMP).[3]
Caffeine approaches 100% bioavailability by the oral route. The volume of distribution is 0.6 L/kg and 36% is protein bound. It is metabolized in the liver by the P450 (CYP) system to active dimethylxanthine stimulants theobromine and theophylline. The elimination t1/2 is 4.5 hours in healthy nonsmoking adults.[3]
Journal for Nurse Practitioners. 2010;6(1):49-52. © 2010
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