Pharmacokinetics

As the drug class would insinuate, inhalants are administered through the process of inhalation, or commonly known as "huffing" (Ridenour, 2005). Once inhaled, the chemical enters the lungs and is absorbed into the bloodstream through a process of diffusion; meaning that it passes through a membrane from an area of high concentration to an area of low concentration. When in the bloodstream one place the chemical immediately travels to is the brain, and since many inhalants were designed to bind lipid molecules (paint thinner, degreaser) the chemicals have a high lipid solubility; effortlessly crossing the blood-brain barrier (Anthony, Warner, & Kessler, 1994). The liver is the other organ that the chemical travels to in order for the chemicals to be metabolized or disposed of. Unfortunately, many of these inhaled chemicals cannot be metabolized, so the chemicals can reenter the brain unchanged (Wood, 2001). Therefore, to totally be rid of these chemicals, they must be expelled from the body; urine, fecal matter, or vomit.
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Pharmacodynamics

Inhalants, like many other depressants are a central nervous system depressant, and their activity on the brain strongly resembles alcohol (Bowen, 2009). Bowen, 2009 further describes inhalant effects on N-Methyl-D-aspartic acid (NMDA) and Gamma-Aminobutyric acid (GABA) receptors. NMDA are glutamate receptors, and inhalants are NMDA antagonists; meaning that the excitation effect of glutamate is inhibited. Inhalant chemicals effect GABA receptors more complicatedly; it causes a surge of calcium into the presynaptic terminal (MacIver, 2009). The presence of calcium is essential for neurotransmitter vesicles to be able to go through the process of exocytosis. Exocytosis is the where the vesicle combines with the synaptic membrane to be then placed into the synaptic cleft. Since, inhalant chemicals increases this process, the effect of GABA is also increased and causes a further depressive effect. Bowen, 2009 has found links to inhalants modulating dopamine transmission, resulting in rewarding effects of inhalant use. This is especially true in limbic pathways, which supports the abuse potential of inhalants (Riegal & French, 2002).