Randomized, controlled dose-optimization studies of dihydroartemisinin-piperaquine for the treatment of uncomplicated multidrug-resistant falciparum malaria in Thailand

BACKGROUND

Dihydroartemisinin-piperaquine (DP) is a new and relatively inexpensive artemisinin-containing fixed-combination antimalarial treatment. An adult treatment course contained 6.4 mg/kg dihydroartemisinin (DHA), which is >40% lower than the level in most artemisinin-containing combinations. This raised the possibility that the efficacy of the current coformulation may not be optimal in the treatment of multidrug-resistant falciparum malaria.

METHODS

In 2 large randomized, controlled studies in Thailand, the recommended dose of DP was compared with a regimen with additional artemisinin derivative (12 mg/kg; DP+) and with mefloquine plus artesunate (MAS3).

RESULTS

A total of 731 patients were included: 201 in a hospital-based study and 530 in a community study. Day-28 cure rates in the hospital-based study were 100% (95% confidence interval [CI], 93.9%-100%) in the MAS3 and DP+ groups and 98.3% (95% CI, 91%-99.7%) in the DP group, with a single recrudescence on day 21. In the community study, polymerase chain reaction genotyping-adjusted cure rates on day 63 were 96.1% (95% CI, 92.6%-99.7%) in the DP group, 98.3% (95% CI, 96.1%-100%) in the DP+ group, and 94.9% (95% CI, 91.2%-98.6%) in the MAS3 group (P=.2). Adverse events were few, with an excess of mild abdominal pain in the DP group.

CONCLUSIONS

The current dosage of DP (6.4 mg/kg DHA and 51.2 mg/kg piperaquine phosphate) given over the course of 48 h is highly effective, safe, and well tolerated for the treatment of multidrug-resistant falciparum malaria, and its efficacy is not improved by the addition of more DHA.

DHEAS as a new diagnostic tool

Dehydroepiandrosterone sulfate (DHEAS) is a 19-carbon steroid, situated along the steroid metabolic pathway. It is the most abundant circulating steroid hormone in the body and can be converted to either androgens or estrogens. Their physiological and pathological functions have not yet been fully identified. Serum DHEAS concentrations peak at around age 25 years and then decline steadily over the following decades. Due to its long half-life and high concentration in the blood, the levels of DHEAS remain the same 24 h a day. This makes DHEAS a very interesting new diagnostic tool for both scientific research and clinical diagnostics. Moreover, circulating concentrations of DHEAS can be changed by many factors, such as endogenous production, hormone supplementation, many kinds of drugs, and many types of disease states. As research moves forward to better understand the relationships of DHEAS with health and disease, it is essential that studies should be designed to control for the influence of many factors on serum DHEAS concentrations.

Azithromycin combination therapy with artesunate or quinine for the treatment of uncomplicated Plasmodium falciparum malaria in adults: a randomized, phase 2 clinical trial in Thailand

BACKGROUND

Because antimalarial drug resistance is spreading, there is an urgent need for new combination treatments for malaria, which kills >1 million people every year. Azithromycin is a macrolide antibiotic that is particularly attractive as an antimalarial because of its safety in children and the extensive experience with its use during pregnancy.

METHODS

We undertook a randomized, controlled, 28-day inpatient trial involving patients with acute, uncomplicated Plasmodium falciparum malaria. We compared the safety and efficacy of 2 azithromycin-artesunate combinations and 2 azithromycin-quinine regimens in adults with malaria. Treatments were as follows: cohort 1 received 3 days of azithromycin (750 mg twice daily) plus artesunate (100 mg twice daily), cohort 2 received 3 days of azithromycin (1000 mg once daily) plus artesunate (200 mg once daily), cohort 3 received 3 days of azithromycin (750 mg twice daily) plus quinine (10 mg/kg twice daily), and cohort 4 received 3 days of azithromycin (500 mg 3 times daily) plus quinine (10 mg/kg 3 times daily). The enrollment target was 25 evaluable subjects per group.

RESULTS

The 28-day cure rates were similarly high in the artesunate and the standard-dose quinine cohorts: 92.0% (95% confidence interval [CI], 74.0%-99.0%), 88.9% (95% CI, 70.8%-97.6%), and 92.0% (95% CI, 74.0%-99.0%), for cohorts 1, 2, and 4, respectively. Late R1 treatment failures were seen in each of the artesunate and the standard-dose quinine cohorts. The cure rate for cohort 3 was 73.3% (95% CI, 44.9%-92.2%). In this cohort, 3 early treatment failures led to the termination of enrollment after 16 subjects had been enrolled. With mean parasite and fever clearance times (+/-SD) of 34+/-13 h and 20+/-20 h, the artesunate combinations were found to have led to a significantly (P<.001) faster clinical and parasitological improvement than occurred in the quinine cohorts (74+/-32 h and 43+/-37 h, respectively). Treatment-related adverse events were significantly more common in the quinine cohorts (P<.001). No deaths or drug-related serious adverse events were observed. In vitro results suggest that the treatment failures--particularly in the low-dose quinine cohort--were associated with decreased susceptibility to quinine, as well as with mefloquine cross-resistance.

CONCLUSIONS

These data suggest that azithromycin-artesunate, even when given only once daily for 3 days, and azithromycin-quinine, given 3 times daily, are safe and efficacious combination treatments for uncomplicated falciparum malaria, and they deserve additional study in special patient populations.

Evaluation of a real-time polymerase chain reaction assay for the diagnosis of malaria in patients from Thailand

We compared the diagnosis of malaria in 297 patients from Thailand by a real-time polymerase chain reaction (PCR) assay using the LightCycler with conventional microscopy using Giemsa-stained thick and thin blood films. The PCR assay can be completed in one hour and has the potential to detect and identify four species of Plasmodium in a single reaction by use of melting temperature curve analysis (however, we did not detect Plasmodium ovale in this study). Blood was collected, stored, and transported on IsoCode STIX, which provide a stable matrix for the archiving and rapid simple extraction of DNA. A genus-specific primer set corresponding to the 18S ribosomal RNA was used to amplify the target sequence. Fluorescence resonance energy technology hybridization probes were designed for P. falciparum over a region containing basepair mismatches, which allowed differentiation of the other Plasmodium species. The PCR results correlated with the microscopic results in 282 (95%) of 297 patient specimens. Most of these were single-species infections caused by P. vivax (150) and P. falciparum (120), along with 5 P. malariae, 2 mixed infections (P. falciparum and P. vivax), and 5 negative specimens. No negative microscopy specimens were positive by PCR (100% specificity for detection of any Plasmodium). The 15 discrepant results could not be resolved, but given the subjective nature of microscopy and the analytical objectivity of the PCR, the PCR results may be correct. The ability of the PCR method to detect mixed infections or to detect P. ovale could not be determined in this study. Within the limitations of initial equipment costs, this real-time PCR assay is a rapid, accurate, and efficient method for the specific diagnosis of malaria. It may have application in clinical laboratories, as well as in epidemiologic studies and antimalarial efficacy trials.

In vitro antimalarial activity of azithromycin, artesunate, and quinine in combination and correlation with clinical outcome

Azithromycin when used in combination with faster-acting antimalarials has proven efficacious in treating Plasmodium falciparum malaria in phase 2 clinical trials. The aim of this study was to establish optimal combination ratios for azithromycin in combination with either dihydroartemisinin or quinine, to determine the clinical correlates of in vitro drug sensitivity for these compounds, and to assess the cross-sensitivity patterns. Seventy-three fresh P. falciparum isolates originating from patients from the western border regions of Thailand were successfully tested for their drug susceptibility in a histidine-rich protein 2 (HRP2) assay. With overall mean fractional inhibitory concentrations of 0.84 (95% confidence interval [CI]=0.77 to 1.08) and 0.78 (95% CI=0.72 to 0.98), the interactions between azithromycin and dihydroartemisinin, as well as quinine, were classified as additive, with a tendency toward synergism. The strongest tendency toward synergy was seen with a combination ratio of 1:547 for the combination with dihydroartemisinin and 1:44 with quinine. The geometric mean 50% inhibitory concentration (IC50) of azithromycin was 2,570.3 (95% CI=2,175.58 to 3,036.58) ng/ml. The IC50s for mefloquine, quinine, and chloroquine were 11.42, 64.4, and 54.4 ng/ml, respectively, suggesting a relatively high level of background resistance in this patient population. Distinct correlations (R=0.53; P=0.001) between quinine in vitro results and parasite clearance may indicate a compromised sensitivity to this drug. The correlation with dihydroartemisinin data was weaker (R=0.34; P=0.038), and no such correlation was observed for azithromycin. Our in vitro data confirm that azithromycin in combination with artemisinin derivatives or quinine exerts additive to synergistic interactions, shows no cross-sensitivity with traditional antimalarials, and has substantial antimalarial activity on its own.

An open label randomized comparison of mefloquine-artesunate as separate tablets vs. a new co-formulated combination for the treatment of uncomplicated multidrug-resistant falciparum malaria in Thailand

BACKGROUND

Delivering drugs in a fixed combination is essential to the success of the strategy of artemisinin-based combination therapy. This prevents one drug being taken without the protection of the other, reducing the chance of emergence and spread of drug resistant strains of Plasmodium falciparum. A lower tablet burden should also facilitate adherence to treatment. A new fixed combination of mefloquine plus artesunate has been developed. This was compared with the conventional regimen of separate tablets for the treatment of uncomplicated multidrug-resistant falciparum malaria.

METHODS

On the north-western border of Thailand 500 adults and children with uncomplicated falciparum malaria were randomized to receive either the new fixed combination or separate tablets. They were followed up weekly for 63 days.

RESULTS

The day 63 polymerase chain reaction-adjusted cure rates were 91.9% (95% CI 88.2-95.6) in the fixed combination group and 89.2% (85.0-93.4) in the loose tablets group (P=0.3). There was a lower incidence of early vomiting in the group receiving the fixed combination.

CONCLUSION

This new fixed combination of mefloquine and artesunate was efficacious, well tolerated and convenient to administer.

Dengue hemorrhagic fever and the liver

Dengue hemorrhagic fever (DHF) is one of the most rapidly emerging infections of tropical and subtropical regions worldwide. It affects more rural and urban areas due to many factors, including climate change. Although most people with dengue viral infection are asymptomatic, approximately 25% experience a self-limited febrile illness with mild to moderate biochemical abnormalities. Severe dengue diseases develop in a small proportion of these patients, and the common organ involvement is the liver. The hepatocellular injury was found in 60%-90% of DHF patients manifested as hepatomegaly, jaundice, elevated aminotransferase enzymes, and critical condition as an acute liver failure (ALF). Even the incidence of ALF in DHF is very low (0.31%-1.1%), but it is associated with a relatively high mortality rate (20%-68.3%). The pathophysiology of liver injury in DHF included the direct cytopathic effect of the DENV causing hepatocytes apoptosis, immune-mediated hepatocyte injury induced hepatitis, and cytokine storm. Hepatic hypoperfusion is another contributing factor in dengue shock syndrome. The reduction of morbidity and mortality in DHF with liver involvement is dependent on the early detection of warning signs before the development of ALF.

Incidence and Clinical Outcome of Acute Liver Failure Caused by Dengue in a Hospital for Tropical Diseases, Thailand

Acute liver failure is an atypical manifestation of dengue with a high mortality. We performed a retrospective cohort study at the Hospital for Tropical Diseases, Bangkok, Thailand. In total, 1,926 patients with serologically confirmed dengue were enrolled in the study from 2011 to 2015. Of these, six patients presented with acute liver failure, four died, and two survived. The incidence of dengue-associated acute liver failure was 0.31%. Dengue-associated acute liver failure was most common among young adults (median age, 29 years). The median duration from onset of fever to development of acute liver failure was 7.5 days. Patients with the severe stage of dengue had a higher risk of developing acute liver failure (P < 0.001). The baseline risk factors associated with the development of acute liver failure were an age of ≤ 40 years (odds ratio [OR] = 1.5, 95% confidence interval [CI] = 1.1-2.0, P < 0.05), a > 10% ratio of atypical lymphocytes (OR = 2.3, 95% CI = 1.8-3.0, P < 0.001), and a platelet count of < 50,000 mm3 (OR = 2.8, 95% CI = 2.2-3.6, P < 0.001). The incidence of acute liver failure in patients with dengue was quite low, but its impact on morbidity, mortality, and poor clinical outcomes was significant. In summary, this study indicates that various baseline risk factors are associated with acute liver failure in patients with dengue.

Short report: detection of Orientia tsutsugamushi in clinical samples by quantitative real-time polymerase chain reaction

Orientia tsutsugamushi infection causes scrub typhus, a common zoonosis of rural Asia. Orientia tsutsugamushi was recently detected by a real-time quantitative polymerase chain reaction (qPCR) assay in animal specimens. We evaluated the same qPCR assay in specimens obtained from patients with serologically proven scrub typhus infections. The 47-kDa qPCR assay was more sensitive than was mouse inoculation; it was reactive in whole blood specimens from all 10 isolate-positive patients and in 7 of 17 isolate-negative individuals (P = 0.003, Fisher's two-tailed exact test). As few as 1,076 O. tsutsugamushi copies/microL were detected in whole blood. Four of 7 sera from isolate-proven scrub typhus infections were also reactive by qPCR. The assay was unreactive in all 12 individuals without scrub typhus infection. This is the first demonstration of a sensitive and specific real-time qPCR assay for human scrub typhus infection.

Cardiac troponin T: its role in the diagnosis of clinically suspected acute myocarditis and chronic dilated cardiomyopathy in children

This study was conducted to assess the use of the serum cardiac troponin T (cTnT) level as a noninvasive indicator to differentiate acute myocarditis and chronic dilated cardiomyopathy in pediatric patients. Myocarditis and dilated cardiomyopathy are clinically difficult to differentiate. Endomyocardial biopsy proved to be quite useful. However, the nature of the procedure--invasiveness, time-consuming, and limited sensitivity--caused some concerns, especially in pediatric patients. Hence, we attempted to find an alternative method that could give a prompt diagnosis of acute myocarditis. Twenty cases with clinically suspected myocarditis or dilated cardiomyopathy and a control group of 21 cases with moderate left-to-right shunt and congestive heart failure were recruited. History, physical examination, electrocardiogram, chest roentgenogram, echocardiogram, cTnT, creatine kinase MB isoenzyme (CK-MB mass), and/or endomyocardial biopsy were compared. The gold standard used to diagnose myocarditis is endomyocardial biopsy (Dallas criteria) and/or recovery from cardiovascular problems within 6 months of follow-up. Ten patients were diagnosed as having myocarditis (group 1) and 10 with chronic dilated cardiomyopathy (group 2). The control group of 21 cases was designated as group 3. The median serum cTnT levels were 0.088 (0.04-3.11), 0.010 (0.010-0.990), and 0.010 (0.010-0.550) ng/ml in groups 1, 2, and 3, respectively. The mean CK-MB mass level for groups, 1, 2, and 3 were 18.35 (7.14-70.00), 4.80 (0.54-108.00), and 2.26 (0.95-7.06) ng/ml. The study showed that both the cTnT and CK-MB mass levels were significantly higher in group 1 than either group 2 or group 3. Histopathology was studied in 9 cases. In 2 of 5 cases and in all 4 cases in group 1 and group 2 histopathology was pathologically proved. Levels of cTnT and CK-MB were significantly higher for myocarditis than for dilated cardiomyopathy and left-to-right shunt with CHF. Further study is needed to assess the optimum cTnT level for differentiating both conditions.

Antiviral Drugs and Acute Kidney Injury (AKI)

The introduction of more efficient antiviral drugs are common cause drug-induced acute kidney injury (AKI). The true prevalence of antiviral drugs induced nephrotoxicity is hardly determined. It causes AKI by many mechanisms including acute tubular necrosis (ATN), allergic interstitial nephritis (AIN), and crystal nephropathy. ATN has been described with a few kinds of antiviral drugs such as cidofovir, adefovir and tenofovir with unique effects on transporter defects, apoptosis, and mitochondrial injury. AIN from atazanavir is a rapid onset of AKI and usually nonoliguric but dialytic therapy are needed because of severity. Additionally, crystal nephropathy from acyclovir, indinavir, and foscarnet can cause AKI due to intratubular obstruction. In this article, the mechanisms of antiviral drug-induced AKI were reviewed and strategies for preventing AKI were mentioned.

Systemic treatment for metastatic colorectal cancer

Significant progress has been achieved in the treatment of metastatic colorectal cancer (mCRC) patients during the last 20 years. There are currently numerous treatments available for the first-line treatment of mCRC. Sophisticated molecular technologies have been developed to reveal novel prognostic and predictive biomarkers for CRC. The development of next-generation sequencing and whole-exome sequencing, which are strong new tools for the discovery of predictive molecular biomarkers to facilitate the delivery of customized treatment, has resulted in tremendous breakthroughs in DNA sequencing technology in recent years. The appropriate adjuvant treatments for mCRC patients are determined by the tumor stage, presence of high-risk pathologic characteristics, microsatellite instability status, patient age, and performance status. Chemotherapy, targeted therapy, and immunotherapy are the main systemic treatments for patients with mCRC. Despite the fact that these novel treatment choices have increased overall survival for mCRC, survival remains optimal for individuals with non-metastatic disease. The molecular technologies currently being used to support our ability to practice personalized medicine; the practical aspects of applying molecular biomarkers to regular clinical practice; and the evolution of chemotherapy, targeted therapy, and immunotherapy strategies for the treatment of mCRC in the front-line setting are all reviewed here.

New fixed-dose artesunate-mefloquine formulation against multidrug-resistant Plasmodium falciparum in adults: a comparative phase IIb safety and pharmacokinetic study with standard-dose nonfixed artesunate plus mefloquine

A new fixed-dose artesunate (AS)-mefloquine (MQ) was assessed in adults hospitalized for 28 days with uncomplicated drug-resistant falciparum malaria. The patients (n = 25/arm) were treated with (i) two fixed-dose tablets (AS-MQ arm; 100 mg AS-200 mg MQ/tablet) daily for 3 days (days 0, 1, and 2) or (ii) nonfixed AS (AS-plus-MQ arm; 4 mg/kg of body weight/day for 3 days) plus MQ (15 mg/kg on day 1 and 10 mg/kg on day 2), dosed by weight. Clinical laboratory electrocardiogram (ECG), adverse events (AEs), efficacy, and pharmacokinetic parameters were assessed over 28 days. Both regimens were well tolerated. No AEs were drug related. Two serious AEs of malaria-induced hypotension occurring in the AS-MQ arm necessitated rescue treatment. There were no significant changes in hematology, biochemistry, or PR and QRS intervals. For all patients, mean Fridericia-corrected QT intervals were significantly (P < or = 0.0027) prolonged on day 3 (407 ms) and day 7 (399 ms) versus day 0 (389 ms), in parallel with significant (P < or = 0.0003) falls in heart rates (67 [day 3], 73 [day 7], and 83 [day 0] beats/minute). Fixed-nonfixed formulations were bioequivalent for MQ, but not for AS and dihydroartemisinin (DHA). One AS-MQ patient developed a new infection on day 28; his day 28 plasma MQ concentration was 503.8 ng/ml. Fixed-dose AS-MQ was well tolerated, had pharmacokinetic (PK) profiles broadly similar to those of nonfixed AS plus MQ, and is a suitable replacement.

Increased fluidity and oxidation of malarial lipoproteins: relation with severity and induction of endothelial expression of adhesion molecules

INTRODUCTION

Oxidative stress has been demonstrated in malaria. The potential oxidative modification of lipoproteins derived from malaria patients was studied. These oxidized lipids may have role in pathogenesis of malaria.

METHOD

The plasma lipid profile and existence of oxidized forms of very low density lipoprotein (VLDL), low density lipoprotein (LDL) and high density lipoprotein (HDL) were investigated in malaria (17 mild and 24 severe patients) and 37 control subjects. Thiobarbituric acid reactive substances (TBARs), conjugated dienes, tryptophan fluorescence and fluidity of lipoproteins were determined as markers of oxidation. The biological effect of malarial lipoproteins was assessed by the expression of adhesion molecules on endothelial cells.

RESULTS

Malarial lipoproteins had decreased cholesterol (except in VLDL) and phospholipid. The triglyceride levels were unchanged. The cholesterol/phospholipid ratio of LDL was decreased in malaria, but increased in VLDL and HDL. TBARs and conjugate dienes were increased in malarial lipoproteins, while the tryptophan fluorescence was decreased. The fluidity of lipoproteins was increased in malaria. These indicated the presence of oxidized lipoproteins in malaria by which the degree of oxidation was correlated with severity. Of three lipoproteins from malarial patients, LDL displayed the most pronounced oxidative modification. In addition, oxidized LDL from malaria patients increased endothelial expression of adhesion molecules.

CONCLUSION

In malaria, the lipoproteins are oxidatively modified, and the degree of oxidation is related with severity. Oxidized LDL from malarial patients increases the endothelial expression of adhesion molecules. These suggest the role of oxidized lipoproteins, especially LDL, on the pathogenesis of disease.

Tuberculosis of the spine

Pott's spine, commonly known as spinal tuberculosis (TB), is an extrapulmonary form of TB caused by Mycobacterium TB. Pott's paraplegia occurs when the spine is involved. Spinal TB is usually caused by the hematogenous spread of infection from a central focus, which can be in the lungs or another location. Spinal TB is distinguished by intervertebral disc involvement caused by the same segmental arterial supply, which can result in severe morbidity even after years of approved therapy. Neurological impairments and spine deformities are caused by progressive damage to the anterior vertebral body. The clinical, radiographic, microbiological, and histological data are used to make the diagnosis of spinal TB. In Pott's spine, combination multidrug antitubercular therapy is the basis of treatment. The recent appearance of multidrug-resistant/extremely drug-resistant TB and the growth of human immunodeficiency virus infection have presented significant challenges in the battle against TB infection. Patients who come with significant kyphosis or neurological impairments are the only ones who require surgical care. Debridement, fusion stabilization, and correction of spinal deformity are the cornerstones of surgical treatment. Clinical results for the treatment of spinal TB are generally quite good with adequate and prompt care.

Prevalence and clinical significance of hepatitis C virus infection in Thai patients with thalassemia

Hepatitis C virus (HCV) infection is a common cause of liver disease in thalassemia major patients in Western, especially Mediterranean, countries. Its significance in thalassemic patients from Southeast Asia has not been critically evaluated. In this report, we describe our study of the prevalence of HCV infection among Thai patients with thalassemia. The relationships of the infection to blood transfusion and the infection's effects on liver function have also been determined. Of the 104 patients studied, 21 (20.2%) tested positively by enzyme immunoassay for anti-HCV antibody, whereas only 2 patients (2%) had the hepatitis B surface antigen. There was no significant relationship between the presence of anti-HCV antibodies and the number and frequency of blood transfusions. In fact, 2 patients (10%) who tested positive for anti-HCV antibodies had never received transfusions. Patients with anti-HCV antibodies had significantly abnormal liver functions, such as higher levels of serum aspartate aminotransferase (SGOT) and alanine aminotransferase (SGPT) and lower levels of serum albumin, compared with patients without anti-HCV antibodies (P = .021, .017, and .004, respectively). However, there were also significant correlations between iron status as indicated by transferrin saturation or serum ferritin levels and SGOT, SGPT, and gamma-glutamyltransferase (GGT) levels. Moreover, abnormal liver function as represented by elevated levels of SGOT, SGPT, GGT, and serum alkaline phosphatase was observed more frequently in patients with iron overload than in patients with a lower degree of iron burden. The presence of HCV did not alter the effects of iron overload on liver function. The findings suggest that both HCV and iron overload are the main causes of abnormal liver function in Thai patients with thalassemia. The treatment of both problems, if coexisting in patients with thalassemia, is required to prevent progression to chronic liver disease.

Emergence and clearance of gametocytes in uncomplicated Plasmodium falciparum malaria

We reviewed the records of 1,175 patients with uncomplicated Plasmodium falciparum malaria to determine the prevalence of gametocytemia. All patients were admitted and received artemisinin combination therapy. Blood films were checked daily until discharge. Circulating gametocytes were observed in 240 (20.2%) of patients and in most cases (222 of 240, 92.5%) gametocytemia was detected during the first 24 hours after admission. Gametocytes were first seen in 174 cases on admission, in 24 cases at 12 hours, and in 24 cases at 24 hours. The longest interval between admission and first appearance of gametocytes was 192 hours. The median gametocyte clearance time was 163 hours (range = 12-806) in the 219 patients in whom gametocytemia resolved. However, 21 patients (9.8%) still had gametocytemia on discharge. Gametocytemia generally is present within the first 24 hours after admission, and emerges in only 1.9% of patients later on during treatment with artemisinin.

Potassium-competitive acid blockers and gastroesophageal reflux disease

Proton pump inhibitors (PPIs), the most commonly used antisecretory medi-cations in the management of reflux illness, virtually eliminate elective surgery for ulcer disease, and relegate anti-reflux surgery to patients with gastroesophageal reflux disease (GERD) who are inadequately managed by medical therapy. However, PPI medications still leave some therapeutic demands of GERD unmet. Furthermore, up to 40%-55% of daily PPI users have chronic symptoms, due to PPI refractoriness. Potassium-competitive acid blockers (P-CABs) transcend many of the problems and limits of PPIs, delivering quick, powerful, and extended acid suppression and allowing for treatment of numerous unmet needs. Recently, it has become clear that compromised mucosal integrity plays a role in the etiology of GERD. As a result, esophageal mucosal protection has emerged as a novel and potential treatment approach. An increasing body of research demonstrates that when P-CABs are used as primary drugs or add-on drugs (to regular treatment), they provide a considerable extra benefit, particularly in alleviating symptoms that do not respond to PPI therapy.

Efficacy of atovaquone-proguanil for treatment of acute multidrug-resistant Plasmodium falciparum malaria in Thailand

A combination of atovaquone-proguanil (Malarone); GlaxoSmithKline, Research Triangle Park, NC) was previously shown to be highly effective in the treatment of uncomplicated Plasmodium falciparum malaria. However, there are only limited recent efficacy data, particularly from regions of multidrug resistance. In this study, we examined the efficacy of atovaquone-proguanil for the treatment of uncomplicated P. falciparum malaria on the Thailand-Myanmar border. Patients were given directly observed atovaquone-proguanil (1,000 mg/400 mg) once a day for three days and followed-up for four weeks in a non-transmission area. Of 140 eligible patients enrolled in this open-label study, 97.8% (95% confidence interval = 95.4-100%) responded to therapy and remained clear of parasitemia at follow-up. Mean parasite clearance time was 41.9 hours and mean fever clearance time was 37.1 hours. On the basis of genotyping, three cases of treatment failure were identified (1 RIII and 2 RI). These data indicate that atovaquone-proguanil remains highly efficacious for the treatment of multidrug-resistant P. falciparum malaria in Thailand.

Effect of HbE and HbH on HbA1C level by ionic exchange HPLC comparing to immunoturbidimetry

BACKGROUND

The hemoglobin (Hb)A1C level is widely used to monitor diabetes mellitus patients. The N-terminal amino acid valine of its beta chain is glycated. The assay of HbA1C is based on differences in the charge, chemical and structural properties of the protein.

METHODS

There are fully automated instruments available in clinical chemistry laboratory to assay HbA1C level. The effect of hemoglobinopathies was studied between an ionic exchange high-pressure liquid chromatography (HPLC) (Bio-Rad Laboratories, USA) and immunoturbidimetry (BM/Hitachi 912 with Roche HBA1CII, Germany-Japan) assay. The influence of high level HbF relative to the HbA1C level by ionic exchange HPLC is known. The effect of HbE and HbH to the HbA1C level by ionic exchange HPLC comparing to immunoturbimetry was examined. The evaluation was performed on 34 normal controls (A2A), 17 beta thalassemia traits (A2 upward arrow A), 36 HbE heterozygotes (EA), 37 HbE homozygotes (EE), 36 beta thalassemia/HbE (EF/EFA), 11 EABart's diseases (EABart's), 34 Hb H diseases (A2/CSAH) and 13 cord blood samples (FA).

CONCLUSIONS

Hemoglobinopathies can impact on the assay of HbA1C level such as HbE and HbH to ionic exchange HPLC. Although not studied as yet, this effect may influence the other methods such as affinity chromatography.

Effect of artesunate and mefloquine in combination on the Fridericia corrected QT intervals in Plasmodium falciparum infected adults from Thailand

OBJECTIVE

To ascertain whether mefloquine (MQ) produces electrocardiogram (ECG) changes that could be a risk for Torsades de Pointe (TdP), a potentially malignant, ventricular tachyarrhythmia.

METHODS

We measured the Fridericia corrected QT (QTcF) intervals on 12 lead ECGs on days (D) 0, 3, 7 in Plasmodium falciparum infected adults, treated with oral artesunate (AS) and MQ as a new fixed dose (n = 25) combination or loose tablets (n = 25) over 3 days. Target total doses were 12 mg/kg of AS and 24-25 mg/kg of MQ. MQ concentrations ([MQ]) were measured by HPLC.

RESULTS

All ECG intervals were similar between drug arms and were combined for analysis. Mean QTcF values were 389 (D0), 407 (D3) and 399 (D7) ms (Ps < 0.003 vs. D0); corresponding heart rates and [MQ]s were 83, 67 and 73 beats/minute (Ps ≤ 0.0003 vs. D0) and 0, 3095 and 1721 ng/ml. One male patient (loose arm) had a D3 QTcF 504 ms (D0 406 ms, D7 433 ms). In the modelling of QTcF and JTcF from D0 to D7, significant effects were observed individually for [MQ], temperature and heart rate (HR). The MQ AUC(0-∞) was not a significant factor. Using a manual descending, model building approach to select variables, the HR was the only significant variable (P = 0.001) over time in the model that best explained the changes in the QTcF and JTcF intervals.

CONCLUSIONS

In this small group of patients, slowing heart rates due to malaria resolution best explained the observed increases in the QTcF intervals.

An open-label crossover study to evaluate potential pharmacokinetic interactions between oral oseltamivir and intravenous zanamivir in healthy Thai adults

There is no parenteral formulation of the neuraminidase inhibitor oseltamivir, the most widely used anti-influenza virus drug. Oseltamivir resistance is an increasing problem. Zanamivir is effective against the most prevalent oseltamivir-resistant influenza viruses. A parenteral formulation of zanamivir is in development for the treatment of severe influenza. It is not known if there is any pharmacokinetic interaction between the two drugs. Sixteen healthy Thai adult volunteers were studied in an open-label, four-period, randomized two-sequence crossover pharmacokinetic study in which zanamivir was given by constant-rate infusion or slow intravenous injection either alone or together with oral oseltamivir. Plasma concentration profiles of oseltamivir, the active metabolite oseltamivir carboxylate, and zanamivir were measured by liquid chromatography-mass spectrometry-mass spectrometry. Both drugs were well tolerated alone and in combination. The maximum plasma concentrations and the areas under the plasma concentration-time curves (AUC) of oseltamivir and oseltamivir carboxylate were not significantly different when oseltamivir was given separately or together with zanamivir. Maximum plasma concentrations of zanamivir were 10% (95% confidence interval, 7 to 12%) higher when zanamivir was infused concurrently with oral oseltamivir than with infusions before or after oral oseltamivir. The plasma zanamivir total AUC was positively correlated with the total oseltamivir carboxylate AUC (Pearson's correlation coefficient [r(P)] = 0.720, P = 0.002, n = 16) but not with the oseltamivir AUC (r(p) = 0.121, n = 16). There is no clinically significant pharmacokinetic interaction between oseltamivir and zanamivir.

Incidence of health problems in travelers to Southeast Asia: a prospective cohort study

BACKGROUND

There are few studies of the incidence of health problems among travelers to Southeast Asia. The current study sought to determine the incidence of self-reported health problems among travelers visiting the region.

METHODS

A prospective questionnaire-based study was conducted among travelers from high-income countries who visited Southeast Asia. Participants were enrolled at time of their pre-travel visit at Mahidol University, Bangkok, Thailand. Travelers were prospectively followed by self-administered questionnaires 2 weeks after arrival, upon return to their home country and 2 weeks after return.

RESULTS

During January 2018-February 2019, 359 travelers were enrolled in Bangkok, Thailand, and the first questionnaire was administered. Follow-up questionnaires were returned by 191, 96 and 64 participants 2 weeks later, at the end of the trip and 2 weeks after return, respectively. A total of 6094 travel days were included in the final analysis. The incidence of acute diarrhea per month per 1000 travelers was 217 [95% confidence interval (CI), 189-248] episodes; skin problems, 197 (95% CI, 170-227); respiratory symptoms, 133 (95% CI, 111-158); fever, 49 (95% CI, 36-65); and potential rabies exposure, 34 (95% CI, 24-48). The incidence of acute diarrhea episodes per month per 1000 travelers was significantly higher during the first 2 weeks of travel compared with subsequent weeks of travel: 325 (95% CI, 291-362) vs 132 (95% CI, 110-1157) (P < 0.05). The incidence of outpatient visits and hospitalizations per month per 1000 travelers was 49 (95% CI, 36-65) and 5 (95% CI, 2-10), respectively.

CONCLUSIONS

In this prospective cohort study we observed substantial burden of acute diarrhea and skin and respiratory symptoms among travelers to Southeast Asia. The higher incidence of diarrhea in the first 2 weeks of travel should be further investigated.

A new alpha chain variant Hb Tonosho [alpha 110(G17)Ala----Thr]: subunit dissociation during cation exchange chromatography for Hb A1c assay

A new alpha chain variant, alpha 110(G17)Ala----Thr, was detected because of subunit dissociation during the determination of the Hb A1c by automated cation exchange high performance liquid chromatography. The abnormal hemoglobin overlapped the cathodic edge of the band of Hb A in isoelectrofocusing. It was slightly unstable in the isopropanol test and had a slightly increased oxygen affinity. The abnormal alpha chain eluted slightly faster than the normal alpha chain in reversed phase high performance liquid chromatography. The amino acid substitution was determined by purification of S-alkylated alpha T-12,13 tryptic peptide, chymotryptic digestion, and sequencing of an octapeptide alpha 110-117. The abnormal alpha chain comprised about 14% of the total alpha chain. A biosynthetic study did not suggest selective loss of the abnormal chain in reticulocytes.

Chronic hepatitis B: New potential therapeutic drugs target

Chronic hepatitis B (CHB) infection remains the most causative agent of liver-related morbidity and mortality worldwide. It impacts nearly 300 million people. The current treatment for chronic infection with the hepatitis B virus (HBV) is complex and lacks a durable treatment response, especially hepatitis B surface antigen (HBsAg) loss, necessitating indefinite treatment in most CHB patients due to the persistence of HBV covalently closed circular DNA (cccDNA). New drugs that target distinct steps of the HBV life cycle have been investigated, which comprise inhibiting the entry of HBV into hepatocytes, disrupting or silencing HBV cccDNA, modulating nucleocapsid assembly, interfering HBV transcription, and inhibiting HBsAg release. The achievement of a functional cure or sustained HBsAg loss in CHB patients represents the following approach towards HBV eradication. This review will explore the up-to-date advances in the development of new direct-acting anti-HBV drugs. Hopefully, with the combination of the current antiviral drugs and the newly developed direct-acting antiviral drugs targeting the different steps of the HBV life cycle, the ultimate eradication of CHB infection will soon be achieved.