Quinacrine

Quinacrine, also known as mepacrine and marketed under the brand name Atabrine, is a synthetic acridine derivative with antiprotozoal activity. It has been used primarily as an antimalarial and, in some settings, as an option when chloroquine resistance limited treatment choices. It has also been employed historically for certain intestinal protozoal infections, including giardiasis and amebiasis, though other agents are more commonly used today.

Mechanism of action is not completely understood, but quinacrine is believed to intercalate into parasite DNA and interfere with nucleic acid synthesis, inhibiting replication in Plasmodium species and other protozoa. It is usually given orally and has a relatively long history of clinical use in malaria prophylaxis and treatment.

Adverse effects are a major consideration. Nausea, vomiting, abdominal pain, headaches, and dizziness are common. Skin and mucous membrane reactions, including pruritus and a yellowish skin discoloration from deposition in tissues, can occur. More serious adverse effects include neuropsychiatric symptoms, optic or other ocular toxicity, dermatitis, hepatitis, and hematologic abnormalities; these risks led to restricted use in many settings. Quinacrine is generally avoided in pregnancy and used with caution in individuals with liver disease, blood dyscrasias, or severe skin disorders.

Regulatory status varies by country, but quinacrine has largely been supplanted by safer antimalarial drugs and is not a first-line therapy for malaria in most places. It remains of historical importance and may be encountered in older stock or specific regional programs.