Amodiaquine agranulocytosis

In Vivo Activity of Repurposed Amodiaquine as a Host-Targeting Therapy for the Treatment of Anthrax

Anthrax is caused by Bacillus anthracis and can result in nearly 100% mortality due in part to anthrax toxin. Antimalarial amodiaquine (AQ) acts as a host-oriented inhibitor of anthrax toxin endocytosis. Here, we determined the pharmacokinetics and safety of AQ in mice, rabbits, and humans as well as the efficacy in the fly, mouse, and rabbit models of anthrax infection. In the therapeutic-intervention studies, AQ nearly doubled the survival of mice infected subcutaneously with a B. anthracis dose lethal to 60% of the animals (LD₆₀). In rabbits challenged with 200 LD₅₀ of aerosolized B. anthracis, AQ as a monotherapy delayed death, doubled the survival rate of infected animals that received a suboptimal amount of antibacterial levofloxacin, and reduced bacteremia and toxemia in tissues. Surprisingly, the anthrax efficacy of AQ relies on an additional host macrophage-directed antibacterial mechanism, which was validated in the toxin-independent Drosophila model of Bacillus infection. Lastly, a systematic literature review of the safety and pharmacokinetics of AQ in humans from over 2 000 published articles revealed that AQ is likely safe when taken as prescribed, and its pharmacokinetics predicts anthrax efficacy in humans. Our results support the future examination of AQ as adjunctive therapy for the prophylactic anthrax treatment.

[Immuno-allergic thrombopenias and leukopenias induced by drugs]

Certain types of cytopenia are due to the destruction of blood cells by an antibody, active only in conjunction with a drug which has previously provoked sensitivity in patients when administered in standard doses. Drug-induced thrombocytopenia and leucopenia of allergic origin are relatively rare. They produce characteristic symptoms, i.e. brutal onset and acute development of the disease; healing takes place when the drug in question is withdrawn. Haematological diseases of drug-related aetiology are being brought to light by serological methods which detect the specific antibody for the drug responsible for the accident. The physiopathological mechanism is still not clearly elucidated.

Neutropenia associated with dual antimalarial chemoprophylaxis--use of bone-marrow culture as an aid in further drug management

Bone-marrow culture in soft agar was used to determine the cause of neutropenia in a visitor to Tanzania who had been taking both amodiaquine and proguanil for antimalarial prophylaxis. Desethyl-amodiaquine, a major metabolite of amodiaquine (but not amodiaquine itself, proguanil, cycloguanil or chloroquine) was implicated. Supplementary studies using amodiaquine binding techniques supported the notion that the parent compound, amodiaquine, was not the cause of the neutropenia. The bone-marrow culture technique proved useful in deciding further anti-malarial prophylaxis and in formulating the choice of curative antimalarial therapy, should this have proved necessary. The procedure may help in the managing other such patients with presumed drug-induced blood dyscrasias when the choice of appropriate and effective antimalarial drugs is limited.

Clinical features and management of poisoning due to antimalarial drugs

The toxicities of antimalarial drugs vary because of the differences in the chemical structures of these compounds. Quinine, the oldest antimalarial, has been used for 300 years. Of the 200 to 300 compounds synthesised since the first synthetic antimalarial, primaquine in 1926, 15 to 20 are currently used for malaria treatment, most of which are quinoline derivatives. Quinoline derivatives, particularly quinine and chloroquine, are highly toxic in overdose. The toxic effects are related to their quinidine-like actions on the heart and include circulatory arrest, cardiogenic shock, conduction disturbances and ventricular arrhythmias. Additional clinical features are obnubilation, coma, convulsions, respiratory depression. Blindness is a frequent complication in quinine overdose. Hypokalaemia is consistently present, although apparently self-correcting, in severe chloroquine poisoning and is a good index of severity. Recent toxicokinetic studies of quinine and chloroquine showed good correlations between dose ingested, serum concentrations and clinical features, and confirmed the inefficacy of haemodialysis, haemoperfusion and peritoneal dialysis for enhancing drug removal. The other quinoline derivatives appear to be less toxic. Amodiaquine may induce side effects such as gastrointestinal symptoms, agranulocytosis and hepatitis. The main feature of primaquine overdose is methaemoglobinaemia. No cases of mefloquine and piperaquine overdose have been reported. Overdose with quinacrine, an acridine derivative, may result in nausea, vomiting, confusion, convulsion and acute psychosis. The dehydrofolate reductase inhibitors used in malaria treatment are sulfadoxine, dapsone, proguanil (chloroguanide), trimethoprim and pyrimethamine. Most of these drugs are given in combination. Proguanil is one of the safest antimalarials. Convulsion, coma and blindness have been reported in pyrimethamine overdose. Sulfadoxine can induce Lyell and Stevens-Johnson syndromes. The main feature of dapsone poisoning is severe methaemoglobinaemia which is related to dapsone and to its metabolites. Recent toxicokinetic studies confirmed the efficacy of oral activated charcoal, haemodialysis and haemoperfusion in enhancing removal of dapsone and its metabolites. No overdose has been reported with artemesinine, a new antimalarial tested in the People's Republic of China. The general management of antimalarial overdose include gastric lavage and symptomatic treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

Frequency of severe neutropenia associated with amodiaquine prophylaxis against malaria

6 out of 7 patients with severe neutropenia associated with the use of amodiaquine for malaria prophylaxis amodiaquine (400 mg weekly) plus proguanil (200 mg daily); 1 of these patients had also taken cotrimoxazole and another had taken sulphaguanidine. The 7th patient had taken amodiaquine alone, but at a higher dose. A retrospective analysis suggests that the frequency of severe neutropenia complicating amodiaquine taken prophylactically may be as high as 1 in 2000.

Changes in the morphology of villar epithelial cells adjacent to duodenal ulcers during the process of healing

Fifteen patients with active duodenal ulcers were treated for 6 weeks with ulcerone, aluminium sucrose sulphate, or bromazepam to promote healing. Biopsies taken from the edge of ulcers before treatment showed an epithelium exclusively populated with cells of a mucus-secreting type which resembled those normally found in the gastric antrum. Biopsies taken at endoscopy from the edge of ulcers or scars at time intervals during treatment to endoscopic healing showed, irrespective of the drug used, a sequence of ultrastructural changes in villar epithelial cells, from a gastric secretory to a duodenal absorptive cell type. We suggest that the gastric cells in the duodenum are derived from stem cells in the crypts of Lieberkühn surrounding an ulcer and are produced in response to luminal fluids of abnormally low pH. Their function is probably protective, in that they isolate regions of ulceration from the healthy mucosa and, by the continuous secretion of gastric mucin, protect the ulcer from the harmful effects of luminal acids. Their transformation to absorptive cells during ulcer healing is part of a natural sequence that is aided by, but not dependent on, drug therapy.