Amikhellin (AK), an antimitotic drug, is a synthetic water-soluble derivative of khellin, an alkaloid extracted from seeds of Ammi Visnaga. Amikhellin has been used so far mostly as a vasodiator. Amikhellin binds to double-stranded DNA by an intercalation process. It inhibits the DNA-polymerase from murine sarcoma leukemia virus.

Amidapsone (aminoureidosulfone) is an urea analog of dapsone used in treatment of herpesvirus caused Marek's diseases.

TS-410 (Amelometasone), is a topical anti-inflammatory steroid. Amelometasone lotion - external steroid preparation - is marketed in Japan.

Alprafenone [AH 141], a phenylpropanone derivative, is presently classified as a class Ic antiarrhythmic agent, it is a sodium channel antagonist. Alprafenone's range of actions is consistent with that of other effective antiarrhythmic drugs and is very similar to that of propafenone. Alprafenone was under preclinical development with Helopharm (Germany), but later this development was discontinued.

Aloxistatin (E64d) is an irreversible and membrane-permeable cysteine protease inhibitor. Aloxistatin was developed for treating muscular dystrophy. Open trials on 73 Duchene’s muscular dystrophy patients were conducted for 3 years at four Japanese national sanatoriums and resulted in some muscle strength improvement but the results were inconclusive and final double-blind studies did not confirm the results. Taisho has discontinued development of aloxistatin for the potential treatment of muscular dystrophy. The  trials completed through Phase 3. In animal models Aloxistatin (100 mg/kg, p.o.) strongly inhibits the cathepsin B&L activities in the skeletal muscle, heart and liver of hamsters. In spinal cord injury (SCI) rats, Aloxistatin provides neuroprotection in SCI lesion and penumbra.Aloxistatin reduces brain amyloid-β and improves memory deficits in Alzheimer's disease animal models by inhibiting cathepsin B activity.

Alphameprodine (ACSCN 9604) is an opioid analgesic classified by the United States Drug Enforcement Administration under Schedule I of illegal substances. The stereoisomer betameprodine is similarly classified, however alphameprodine is more widely used (both are referred to as Meprodine). Alphameprodine is a structural analogue of meperidine. It exerts physiological effects characteristic of opioids, such as analgesia, euphoria and sedation, as well as itching, nausea, and respiratory depression.

Geroquinol (geranylhydroquinone) is a radioprotective agent. It is also the major contact allergen of Phacelia Crenulate (a flowering plant in the borage family), which causes skin irritation comparable in degree to the skin reaction to urushiol, the sap found in poison oak/ivy. There is no cross-reaction with poison oak or ivy.

Dimelazine is a sedative, antihistaminic agent.

Dimepregnen is an antiestrogen agent.

Dimenoxadol is an opioid analgesic which produces typical opioid effects such as analgesia and sedation. It is structurally similar to methadone and is a benzilic acid derivative. In the United States it is classified as a Schedule I controlled drug.