Pharmacological and Physiological Antagonism

Caffeine is a central nervous system (CNS) stimulant commonly consumed through liquids such as coffee, tea, energy drinks and soft drinks but also obtained in powder and pill form. “There are four adenosine receptors: A1, A2A, A2B, and A3. Among the four, A1 and A2A receptors are the ones predominantly expressed in the brain. Caffeine has similar in vitro affinities for A1, A2A” (Fredholm et. al 83)It is believed that caffeine antagonizes the intoxicating effects of alcohol by blocking the adenosine A1 receptors that mediate alcohol's effects. According to Biochemical, Physiological and Molecular Aspects of Human Nutrition, “caffeine increases neural activity in the brain by suppressing adenosine. ” According to Human Biochemistry and Disease, “by counteracting adenosine, caffeine significantly reduces blood flow to the brain, which leads to headaches, dizziness and reduced fine motor coordination.