Glucose-6-phosphate dehydrogenase deficiency, chlorproguanil-dapsone with artesunate and post-treatment haemolysis in African children treated for uncomplicated malaria

The medication for pneumocystis pneumonia with glucose-6-phosphate dehydrogenase deficiency patients

Pneumocystis pneumonia (PCP) is an opportunity acquired infection, which is usually easy to occur in patients with AIDS, organ transplantation, and immunosuppressive drugs. The prevention and treatment must be necessary for PCP patients with immunocompromise. And the oxidants are currently a typical regimen, including sulfanilamide, dapsone, primaquine, etc. Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked gene-disease that affects about 400 million people worldwide. The lack of G6PD in this population results in a decrease in intracellular glutathione synthesis and a weakening of the detoxification ability of the oxidants. As a result, oxidants can directly damage haemoglobin in red blood cells, inducing methemoglobin and hemolysis. When patients with G6PD deficiency have low immunity, they are prone to PCP infection, so choosing drugs that do not induce hemolysis is essential. There are no clear guidelines to recommend the drug choice of this kind of population at home and abroad. This paper aims to demonstrate the drug choice for PCP patients with G6PD deficiency through theoretical research combined with clinical cases.

Neuroprotective effect of dapsone in patients with aneurysmal subarachnoid hemorrhage: a prospective, randomized, double-blind, placebo-controlled clinical trial

OBJECTIVE

In this study, the authors sought to define the differences in the incidence of delayed cerebral ischemia (DCI) between patients treated with dapsone and those treated with placebo. Secondary objectives were to define the clinical outcome at discharge and 3 months and the incidence of brain infarction.

METHODS

A prospective, randomized, double-blind, placebo-controlled study was performed and included patients with aneurysmal subarachnoid hemorrhage (SAH) within 5 days from ictus who were candidates for aneurysm occlusion, and who had a Fisher grade of 3 or 4. Patients with sulfa or sulfone drug allergies, hemoglobin < 11 g/dl, known G6PD deficiency, and those refusing informed consent were excluded. A minimal relevant effect decrease of 35% in the incidence of DCI was established. Patients were randomly assigned to receive a regimen of dapsone 2.5 ml (100 mg) daily or a placebo (aluminum hydroxide suspension, 2.5 ml daily). Both groups received validated treatment for aneurysmal SAH. The appearance of DCI on CT was assessed in every patient at discharge and 3 months later. We used the chi-square test to compare the DCI incidence between both groups, and the Student t-test or nonparametric tests to compare quantitative variables.

RESULTS

Overall, 48 patients (70.8% women and 29.2% men) were included. The mean age was 50 years (SD 14.28 years, range 18-72 years). Prerandomization and postrandomization characteristics were balanced, except for the necessity of intra-arterial nimodipine administration in patients treated with placebo (15.4% vs 45.5%, p = 0.029. The incidence of DCI, the primary endpoint, for the whole cohort was 43.8% and was significantly lower in the dapsone group (26.9% vs 63.6%, p = 0.011). In addition, the irreversible DCI incidence was lower in the dapsone group (11.5% vs 54.5%, p = 0.12). A favorable modified Rankin Scale score was more frequent in the dapsone group at discharge and at 3 months (76.9% vs 36.4%, p = 0.005 and 80% vs 38.9%, p = 0.019, respectively). Also, the brain infarction incidence was lower in the dapsone group (19.2% vs 63.6%, p = 0.001). There was no difference between groups regarding adverse events.

CONCLUSIONS

Dapsone seems to play a role as a prophylactic agent in patients at high risk of developing DCI after aneurysmal SAH. A multicenter investigation is necessary to increase the study population and confirm the consistency of the results observed in this study.

Clinical Application of Pharmacogenetic Markers in the Treatment of Dermatologic Pathologies

Dermatologic pathologies are the fourth most common cause of non-fatal disease worldwide; however, they produce a psychosocial, economic, and occupational impact equal to or greater than other chronic conditions. The most prevalent are actinic keratosis, followed by basal-cell carcinoma, in a lesser proportion acne vulgaris, psoriasis, and hidradenitis suppurativa, among others, and more rarely dermatitis herpetiformis. To treat actinic keratosis and basal-cell carcinoma, 5-fluorouracil (5-FU) 0.5% is administered topically with good results, although in certain patients it produces severe toxicity. On the other hand, dapsone is a drug commonly used in inflammatory skin conditions such as dermatitis herpetiformis; however, it occasionally causes hemolytic anemia. Additionally, biologic drugs indicated for the treatment of moderate-to-severe psoriasis and hidradenitis suppurativa have proved to be effective and safe; nevertheless, a small percentage of patients do not respond to treatment with biologics in the long term or they are ineffective. This interindividual variability in response may be due to alterations in genes that encode proteins involved in the pathologic environment of the disease or the mechanism of action of the medication. Pharmacogenetics studies the relationship between genetic variations and drug response, which is useful for the early identification of non-responsive patients and those with a higher risk of developing toxicity upon treatment. This review describes the pharmacogenetic recommendations with the strongest evidence at present for the treatments used in dermatology, highlighting those included in clinical practice guides. Currently, we could only find pharmacogenetic clinical guidelines for 5-FU. However, the summary of product characteristics for dapsone contains a pharmacogenetic recommendation from the United States Food and Drug Administration. Finally, there is an enormous amount of information from pharmacogenetic studies in patients with dermatologic pathologies (mainly psoriasis) treated with biologic therapies, but they need to be validated in order to be included in clinical practice guides.

Biguanides drugs: Past success stories and promising future for drug discovery

Biguanides have attracted much attention a century ago and showed resurgent interest in recent years after a long period of dormancy. They constitute an important class of therapeutic agents suitable for the treatment of a wide spectrum of diseases. Therapeutic indications of biguanides include antidiabetic, antimalarial, antiviral, antiplaque, and bactericidal applications. This review presents an extensive overview of the biological activity of biguanides and different mechanisms of action of currently marketed biguanide-containing drugs, as well as their pharmacological properties when applicable. We highlight the recent developments in research on biguanide compounds, with a primary focus on studies on metformin in the field of oncology. We aim to provide a critical overview of all main bioactive biguanide compounds and discuss future perspectives for the design of new drugs based on the biguanide fragment.

Targeting Gametocytes of the Malaria Parasite Plasmodium falciparum in a Functional Genomics Era: Next Steps

Mosquito transmission of the deadly malaria parasite Plasmodium falciparum is mediated by mature sexual forms (gametocytes). Circulating in the vertebrate host, relatively few intraerythrocytic gametocytes are picked up during a bloodmeal to continue sexual development in the mosquito vector. Human-to-vector transmission thus represents an infection bottleneck in the parasite's life cycle for therapeutic interventions to prevent malaria. Even though recent progress has been made in the identification of genetic factors linked to gametocytogenesis, a plethora of genes essential for sexual-stage development are yet to be unraveled. In this review, we revisit P. falciparum transmission biology by discussing targetable features of gametocytes and provide a perspective on a forward-genetic approach for identification of novel transmission-blocking candidates in the future.

G6PD Variants and Haemolytic Sensitivity to Primaquine and Other Drugs

Restrictions on the cultivation and ingestion of fava beans were first reported as early as the fifth century BC. Not until the late 19th century were clinical descriptions of fava-induced disease reported and soon after characterised as “favism” in the early 20th century. It is now well known that favism as well as drug-induced haemolysis is caused by a deficiency of the glucose-6-phosphate dehydrogenase (G6PD) enzyme, one of the most common enzyme deficiency in humans. Interest about the interaction between G6PD deficiency and therapeutics has increased recently because mass treatment with oxidative 8-aminoquinolines is necessary for malaria elimination. Historically, assessments of haemolytic risk have focused on the clinical outcomes (e.g., haemolysis) associated with either a simplified phenotypic G6PD characterisation (deficient or normal) or an ill-fitting classification of G6PD genetic variants. It is increasingly apparent that detailed knowledge of both aspects is required for a complete understanding of haemolytic risk. While more attention has been devoted recently to better phenotypic characterisation of G6PD activity (including the development of new point-of care tests), the classification of G6PD variants should be revised to be clinically useful in malaria eliminating countries and in populations with prevalent G6PD deficiency. The scope of this work is to summarize available literature on drug-induced haemolysis among individuals with different G6PD variants and to highlight knowledge gaps that could be filled with further clinical and laboratory research.

Heterogeneity of G6PD deficiency prevalence in Mozambique: a school-based cross-sectional survey in three different regions

Background

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked hereditary enzymatic abnormality that affects more than 400 million people worldwide. Most deficient individuals do not manifest any symptoms; however, several precipitant agents—such as fava intake, infections, or several drugs—may trigger acute haemolytic anaemia. Countries should be informed of the prevalence of this enzymatic anomaly within their borders, in order to make safe and appropriate national decisions regarding the use of potentially unsafe drugs for G6PD deficient individuals.

Methods

A school-based cross-sectional survey was conducted in three districts in Mozambique, namely Manhiça, located in the south; Mocuba in the centre; and Pemba in the northern tip of the country. G6PD deficiency was evaluated using the CareStart™ diagnostic test, and enzyme activity levels were measured through fluorescence spectrophotometry in deficient individuals. Chi squared and ANOVA tests were used to assess prevalence and mean enzyme activity differences, and logistic regression was used to identify risk factors associated to the deficiency.

Results

G6PD deficiency prevalence estimates were lowest in the northern city of Pemba (8.3%) and among Emakhuwas and Shimakondes, and higher in the centre and southern regions of the country (16.8 and 14.6%, respectively), particularly among Elomwes and Xichanganas. G6PD deficiency was significantly more prevalent among male students than females (OR = 1.4, 95% CI 1.0–1.8, p = 0.02), although enzyme activity levels were not different among deficient individuals from either gender group. Finally, median deficiency levels were found to be more severe among the deficient students from the north (0.7 U/gHg [0.2–0.7] p < 0.001) and south (0.7 U/gHg [0.5–2.5]), compared to those from the centre (1.4 U/gHg [0.6–2.1]).

Conclusion

These findings suggest that Mozambique, as a historically high malaria-endemic country has considerable levels of G6PD deficiency, that vary significantly across the country. This should be considered when planning national strategies for the use of licensed drugs that may be associated to haemolysis among G6PD individuals, or prior to the performance of future trials using primaquine and other 8-aminoquinolines derivatives.

Registration Number CISM local ethics committee (CIBS-25/013, 4th of December 2013), and the National Ethics Committee of Mozambique (IRB00002657, 28th of February 2014).

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is associated with asymptomatic malaria in a rural community in Burkina Faso

OBJECTIVE

To investigate 4 combinations of mutations responsible for glucose-6-phosphate dehydrogenase (G6PD) deficiency in a rural community of Burkina Faso, a malaria endemic country.

METHODS

Two hundred individuals in a rural community were genotyped for the mutations A376G, G202A, A542T, G680T and T968C using TaqMan single nucleotide polymorphism assays and polymerase chain reaction followed by restriction fragment length polymorphism.

RESULTS

The prevalence of the G6PD deficiency was 9.5% in the study population. It was significantly higher in men compared to women (14.3% vs 6.0%, P=0.049). The 202A/376G G6PD A- was the only deficient variant detected. Plasmodium falciparum asymptomatic parasitaemia was significantly higher among the G6PD-non-deficient persons compared to the G6PD-deficient (P<0.001). The asymptomatic parasitaemia was also significantly higher among G6PD non-deficient compared to G6PD-heterozygous females (P<0.001).

CONCLUSIONS

This study showed that the G6PD A- variant associated with protection against asymptomatic malaria in Burkina Faso is probably the most common deficient variant.

The prevalence of glucose-6-phosphate dehydrogenase deficiency in Gambian school children

BACKGROUND

Primaquine, the only available drug effective against Plasmodium falciparum sexual stages, induces also a dose-dependent haemolysis, especially in glucose-6-phosphate dehydrogenase deficient (G6PDd) individuals. Therefore, it is important to determine the prevalence of this deficiency in areas that would potentially benefit from its use. The prevalence of G6PD deficiency by genotype and enzyme activity was determined in healthy school children in The Gambia.

METHODS

Blood samples from primary school children collected during a dry season malaria survey were screened for G6PDd and malaria infection. Genotypes for allele mutations reported in the country; 376, 202A-, 968A- and 542 were analysed while enzyme activity (phenotype) was assayed using a semi-quantitative commercial test kit. Enzyme activity values were fitted in a finite mixture model to determine the distribution and calculate a cut-off for deficiency. The association between genotype and phenotype for boys and girls as well as the association between mutant genotype and deficient phenotype was analysed.

RESULTS

Samples from 1,437 children; 51% boys were analysed. The prevalence of P. falciparum malaria infection was 14%. The prevalence of the 202A-, 968 and 542 mutations was 1.8%, 2.1% and 1.0%, respectively, and higher in boys than in girls. The prevalence of G6PDd phenotype was 6.4% (92/1,437), 7.8% (57/728) in boys and 4.9% (35/709) in girls with significantly higher odds in the former (OR 1.64, 95% CI 1.05, 2.53, p = 0.026). The deficient phenotype was associated with reduced odds of malaria infection (OR 0.77, 95% CI 0.36, 1.62, p = 0.49).

CONCLUSIONS

There is a weak association between genotype and phenotype estimates of G6PDd prevalence. The phenotype expression of deficiency represents combinations of mutant alleles rather than specific mutations. Genotype studies in individuals with a deficient phenotype would help identify alleles responsible for haemolysis.

Comparative safety of artemether-lumefantrine and other artemisinin-based combinations in children: a systematic review

Background

The purpose of the study was to compare the safety of artemether-lumefantrine (AL) with other artemisinin-based combinations in children.

Methods

A search of EMBASE (from 1974 to April 2013), MEDLINE (from 1946 to April 2013) and the Cochrane library of registered controlled trials for randomized controlled trials (RCTs) which compared AL with other artemisinin-based combinations was done. Only studies involving children ≤ 17 years old in which safety of AL was an outcome measure were included.

Results

Four thousand, seven hundred and twenty six adverse events (AEs) were recorded in 6,000 patients receiving AL. Common AEs (≥1/100 and <1/10) included: coryza, vomiting, anaemia, diarrhoea, vomiting and abdominal pain; while cough was the only very commonly reported AE (≥1/10). AL-treated children have a higher risk of body weakness (64.9%) than those on artesunate-mefloquine (58.2%) (p = 0.004, RR: 1.12 95% CI: 1.04-1.21). The risk of vomiting was significantly lower in patients on AL (8.8%) than artesunate-amodiaquine (10.6%) (p = 0.002, RR: 0.76, 95% CI: 0.63-0.90). Similarly, children on AL had a lower risk of vomiting (1.2%) than chlorproguanil-dapsone-artesunate (ACD) treated children (5.2%) (p = 0.002, RR: 0.63, 95% CI: 0.47-0.85). The risk of serious adverse events was significantly lower for AL (1.3%) than ACD (5.2%) (p = 0.002, RR: 0.45, 95% CI: 0.27-0.74).

Conclusion

Artemether-lumefantrine combination is as safe as ASAQ and DP for use in children. Common adverse events are cough and gastrointestinal symptoms. More studies comparing AL with artesunate-mefloquine and artesunate-azithromycin are needed to determine the comparative safety of these drugs.