There are approximately 1300 kinds of ethical drugs currently approved for use in Japan, excluding high molecular weight drugs and Chinese medicines. Among them, 81 contain alpha-amino acids, though some consist of a-amino acid parenteral fluid and peptide-type drugs, which include ACE inhibitors. Of these, 30 kinds of drugs are made from both natural and non-natural amino acids, and 51 kinds of drugs are prepared from amino acid derivatives. All of these drugs were developed in the last 50 years. Amino acids moieties such as D-phenylglycine and D-phydroxyphenylglycine have contributed to enhancing the stability, absorbability, and effectiveness of many drugs, particularly antibiotics, such as certain types of penicillin and cephalosporin. In recent years, radioactive and antiviral agents containing amino acid skeletons have also been developed for use as anti-AIDS medications.