Miltefosine: issues to be addressed in the future

Future issues that need to be addressed for miltefosine are efficacy against non-Indian visceral leishmaniasis, efficacy in HIV-coinfected patients, efficacy against the many forms of cutaneous and mucosal disease, effectiveness under clinical practice conditions, generation of drug resistance and the need to provide a second antileishmanial agent to protect against this disastrous event, and the ability to maintain reproductive contraceptive practices under routine clinical conditions.

Atovaquone and proguanil hydrochloride: a review of nonclinical studies

BACKGROUND

Safe and effective antimalarial drugs are needed for treatment and prophylaxis of malaria. The combination of atovaquone and proguanil hydrochloride is a new antimalarial drug combination that has recently become available in many countries.

METHODS

Data were reviewed from nonclinical studies evaluating the microbiology, secondary pharmacology, pharmacokinetics, and toxicology of atovaquone and proguanil hydrochloride.

RESULTS

Atovaquone is highly active against asexual erythrocytic stages of Plasmodium falciparum in vitro (IC50 0.7-6 nM) and in animal models. Proguanil per se has only weak antimalarial activity in vitro (IC50 2.4-19 microM), and its effectiveness depends on the active metabolite cycloguanil (IC50 0.5-2.5 nM). The combination of atovaquone and proguanil is synergistic in vitro. Both drugs also have activity against gametocytes and pre-erythrocytic (hepatic) stages of malaria parasites. Atovaquone is a ubiquinone antagonist that inhibits mitochondrial electron transport and collapses mitochondrial membrane potential. The proguanil metabolite cycloguanil is a dihydrofolate reductase inhibitor, but the mode of action of proguanil is unknown. In screening evaluations of secondary pharmacology, neither atovaquone nor proguanil had activity that adversely affected gastrointestinal, cardiovascular, or central or autonomic nervous system functions at clinically relevant concentrations. After oral administration, atovaquone exposure is extensive in rats but limited in dogs, while proguanil and cycloguanil exposure is extensive in dogs but limited in rats. In both species, toxicity was related to proguanil exposure, the principal manifestations being salivation, emesis, and loss of body weight. Neither atovaquone nor proguanil was teratogenic or mutagenic. An increased incidence of hepatic adenomas and adenocarcinomas was seen in mice, but not rats, after lifetime exposure to atovaquone, and appears to be related to species-specific differences in hepatic enzymatic activity. No additional toxicity was evident in animals treated with the combination of atovaquone and proguanil hydrochloride compared to those treated with either drug alone.

CONCLUSION

Nonclinical studies of atovaquone and proguanil hydrochloride supported the clinical development of this combination for treatment and prophylaxis of malaria.

Cumulative risk of bypass, amputation or death following percutaneous transluminal angioplasty

OBJECTIVE

To define cumulative risk of reconstruction, amputation or death following percutaneous transluminal angioplasty (PTA).

DESIGN

Non-randomised observational study.

PATIENTS AND METHODS

Two hundred and thirty-four PTAs in 212 patients. Minimum follow-up 6 months. Examination of data collected prospectively on manual card index. Examination of radiology and theatre ledgers over 2.5-year period. District Information System (Dis Data). Life-table analysis.

RESULTS

The cumulative risks of reconstruction at 12 months were 14.9% and 6.7%, respectively, following angioplasties below and above the inguinal ligament. Major and minor amputations were more common if the original lesions were below the inguinal ligament (relative risk (RR) 3.32, confidence interval (CI) CI 0.42-26.26 and RR 4.24, CI 0.055-32.9, respectively). They were also more likely in diabetic compared with non-diabetic patients (RR 9.95, CI 2.85-34.47 and RR 3.66, CI 1.28-10.44, respectively). No patient who presented with claudication underwent amputation. Death was more common in patients originally presenting with rest pain or gangrene than claudication (RR 3.94, CI 1.51-10.31).

CONCLUSION

This study confirms the poor outlook of diabetic patients with peripheral vascular disease or those presenting with rest pain, ulceration or gangrene. Percutaneous transluminal angioplasty was associated with approximately 80% limb salvage rate in those patients during the duration of the study.

An outbreak of gastrointestinal illness associated with contamination of the mains supply by river water

In June 1992 a department of public health was informed of an outbreak of illness that was thought to be associated with contamination of the mains water supply to a farm. A field investigation identified 42 cases of acute gastrointestinal illness among 117 people potentially at risk, and found that the mains water supply to the farm was connected to an irrigation system that used water from a river. This outbreak illustrates the danger of connections between potable and non-potable water systems, and emphasises the importance of complying with existing water byelaws.