Amino Acids Used as Drugs

D-Penicillamine (D-/6,/l-dimethylglycine), a metabolite of penicillin, was first isolated in the urine specimens from patients treated with penicillin with liver disease. It is an effective chelator of metals such as copper, zinc, and lead. It is used in the chelation therapy of Wilson s disease, which is characterized by excess copper accumulation leading to hepatolenticular degeneration (Chapter 37). 

A-Acetylcysteine is administered in the ace-toaminophen toxicity. It replenishes the hepatic stores of glutathione (Chapter 17). A-Acetylcysteine is also used in the treatment of pulmonary diseases including cystic fibrosis (Chapter 12). In patients with chronic renal insufficiency, prophylactic oral administration of A-Acetylcysteine have been used in the prevention of further renal impairment due to administration of radiographic contrast agents. In this setting presumably A-Acetylcysteine functions as an antioxidant and augments the vasodilatory effect of nitric oxide via the formation of S-nitrosothiol (Chapter 17). 

Gabapentin is y-aminobutyrate covalently linked to cyclohexane to make it lipophilic and to facilitate its transport across the blood-brain barrier. It is used as an anticonvulsant and in amyotrophic lateral sclerosis (ALS). 

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