Strengthening of national capacity in implementation of antimalarial drug quality assurance in Thailand.

Substandard and counterfeit pharmaceutical products, including antimalarial drugs, appear to be widespread internationally and affect both the developing and developed countries. The aim of the study was to investigate the quality of antimalarial drugs, ie, artesunate (ART), chloroquine (CHL), mefloquine (MEF), quinine (QUI), sulfadoxine/pyrimethamine (S/P) and tetracycline (TT) obtained from the government sector and private pharmacies in 4 Thai provinces: Mae Hong Son, Kanchanaburi, Ranong, and Chanthaburi. Three hundred sixty-nine samples of 6 antimalarial drugs from 27 government hospitals, 27 malaria clinics, and 53 drugstores, were collected.

Early detection of malaria in an endemic area: model development.

A malaria epidemic warning system was established in Thailand in 1984 using graphs displaying the median or mean incidence of malaria over the previous five years compiled from malaria surveillance data throughout the country. This reporting mechanism is not timely enough to detect the occurrence of a malaria epidemic which usually occurs at the district level over a short period of time. An alternative method for early detection of a malaria epidemic employing the Poisson model has been proposed.

Susceptibility to chloroquine, mefloquine and artemisinin of Plasmodium vivax in northwestern Thailand.

The in vitro study had the objectives of monitoring the sensitivity of Plasmodium vivax to chloroquine and artemisinin, and to assess its baseline sensitivity to mefloquine in northwestern Thailand in an area near the border to Myanmar. The investigations were carried out in 2004 at the malaria clinics of Mae Sot, Chedi Ko and Mae Ka Sa, all in the district of Mae Sot, Province of Tak. The in vitro tests followed the method of Tasanor.

Specific pharmacokinetic interaction between lumefantrine and monodesbutyl-benflumetol in Plasmodium falciparum.

The blood schizontocidal activity of lumefantrine, monodesbutyl-benflumetol (DBB) and a 999:1 combination of both compounds has been investigated in 26 fresh isolates of Plasmodium falciparum from northwestern Thailand, using the WHO standard protocol Mark II for determining the inhibition of schizont maturation. The geometric mean cut-off concentrations of schizont maturation (GMCOC) were 943.2 nM for lumefantrine, 146.

Synergistic interaction between atovaquone and retinol in Plasmodium falciparum in vitro.

The study has been conducted with the objective of assessing the blood schizontocidal activities of atovaquone (ATO), retinol (RET) and combinations of both (ATO-RET) at set retinol concentrations corresponding to the 50th, 65th and 80th percentile of the physiological serum retinol levels. The in vitro tests followed the WHO standard protocol Mark II for measuring the inhibition of schizont maturation in Plasmodium falciparum. Valid results for all 5 test lines were obtained with 26 fresh parasite isolates from northwestern Thailand, an area affected by multidrug-resistance.

Pharmacodynamic interaction between atovaquone and other antimalarial compounds against Plasmodium falciparum in vitro.

Atovaquone, a 2-hydroxy-1,4-naphthoquinone, was first introduced as a drug against opportunistic infections in immuno-compromised patients. Early clinical-parasitological experiences in the treatment of malaria were disappointing due to highly variable and poor absorption, a phenomenon typical for naphthoquinones. Proguanil was found to potentiate the activity of atovaquone and the combination of the two drugs was introduced as an antimalarial drug with blood schizontocidal and causal prophylactic activity.

In vitro interaction between artemisinin and chloroquine as well as desbutyl-benflumetol in Plasmodium vivax.

Malaria resulting from infection with Plasmodium vivax rarely causes death, however, patients usually suffer acute debilitating clinical symptoms and the recovery is slow. This study had the objective of assessing the pharmacodynamic interaction between artimisinin and chloroquine with a view of a potential acceleration of the clinicalparasitological response, and the investigation of therapeutic alternatives in the event of chloroquine resistance in Plasmodium vivax. Tests were based on the growth inhibition of Plasmodium vivax, determined by morphological differential counts of 200 asexual parasites.

Deployment of early diagnosis and mefloquine-artesunate treatment of falciparum malaria in Thailand: the Tak Malaria Initiative.

Background: Early diagnosis and treatment with artesunate-mefloquine combination therapy (MAS) have reduced the transmission of falciparum malaria dramatically and halted the progression of mefloquine resistance in camps for displaced persons along the Thai-Burmese border, an area of low and seasonal transmission of multidrug-resistant Plasmodium falciparum. We extended the same combination drug strategy to all other communities (estimated population 450,000) living in five border districts of Tak province in northwestern Thailand.

Methods And Findings: Existing health structures were reinforced.

Chronicle of malaria epidemics in Thailand, 1980-2000.

The occurrence of malaria epidemics in Thailand was reviewed from the malaria surveillance report of the National Malaria Control Program. The literature review revealed that the four epidemic periods recorded during 1980-2000 almost always occurred in the provinces and districts located along international borders. Malaria epidemics are caused by various factors such as: extensive population movement, multi-drug resistance development, low immune status of the population, lack of knowledge and appropriate personal protection against mosquito biting, and the re-emergence of malaria transmission in low malarious areas.

In vitro activity of artemisinin alone and in combination with retinol against Plasmodium falciparum.

Increasing resistance of Plasmodium falciparum to antimalarial drugs is an important public health problem, demanding novel therapeutic approaches. This study had the objective of assessing the in vitro activity of artemisinin and its combination with retinol in fresh isolates of P. falciparum in an area with a high proportion of multidrug-resistant strains.

Synergism of desbutyl-benflumetol and retinol against Plasmodium falciparum in vitro.

This in vitro study was conducted to assess the blood schizontocidal activity of desbutyl-benflumetol (DBB), a new benzindene derivative, retinol and a combination of both compounds. The tests were carried out according to the methodology of the WHO standard test Mark II, measuring the drug-dependent inhibition of schizont maturation, and using 43 fresh isolates of Plasmodium falciparum from northwestern Thailand, an area with established multidrug-resistance. DBB and retinol showed a mean 50% effective concentration (EC-50) of 3.

Mekong malaria. II. Update of malaria, multi-drug resistance and economic development in the Mekong region of Southeast Asia.

In an expansion of the first Mekong Malaria monograph published in 1999, this second monograph updates the malaria database in the countries comprising the Mekong region of Southeast Asia. The update adds another 3 years' information to cover cumulative data from the 6 Mekong countries (Cambodia, China/Yunnan, Lao PDR, Myanmar, Thailand, Viet Nam) for the six-year period 1999-2001. The objective is to generate a more comprehensive regional perspective in what is a global epicenter of drug resistant falciparum malaria, in order to improve malaria control on a regional basis in the context of social and economic change.

Declining mefloquine sensitivity of Plasmodium falciparum along the Thai-Myanmar border.

Mefloquine sensitivity of Plasmodium falciparum along the Thai-Myanmar border, both in vitro and in vivo, following different first-line treatments for uncomplicated falciparum malaria patients in these areas during the period 1997--2003 were studied. Standard in vitro micro tests and in vivo efficacy according to World Health Organization methodologies were performed. P.

Comparative study on the in vitro activity of lumefantrine and desbutyl-benflumetol in fresh isolates of Plasmodium vivax from Thailand.

The occurrence of chloroquine resistance in Plasmodium vivax underlines the need for monitoring the drug response of this important malaria parasite and for the evaluation of alternative therapeutic agents. In-vitro methods facilitate these tasks. This investigation employed a recently developed in-vitro micro-technique and validated it for lumefantrine and desbutyl-benflumetol, a compound that was initially considered a metabolite of lumefantrine.

In vitro sensitivity of Plasmodium falciparum to lumefantrine in north-western Thailand.

Lumefantrine (benflumetol) belongs to the class-2 blood schizontocidal compounds. In combination with artemether it serves as an alternative drug for treating chloroquine-resistant infections with Plasmodium falciparum. In view of activity correlations with mefloquine, it is important to monitor the parasite's intrinsic sensitivity to lumefantrine in areas with multi-drug resistant P.

Comparative study of the in vitro sensitivity of Plasmodium falciparum to artemisinin in two border areas of Thailand.

Artesunate was introduced in Thailand in 1995 for the treatment of falciparum malaria in areas of multidrug resistance, where it is used in combination with mefloquine. The studies were conducted between May and August 1999, 2000 and 2001 in the provinces Mae Hong Son and Tak (Mae Sot District) in northwestern Thailand, both on the border to Myanmar. The province of Mae Hong Son is still largely unaffected by multidrug resistance and infections with Plasmodium falciparum are treated with mefloquine alone.

Trend of malaria incidence in highly endemic provinces along the Thai borders, 1991-2001.

The intercountry border areas of Thailand have high malaria receptivity and vulnerability that present numerous problems in the control of malaria transmission. This study focused on the 30 provinces of Thailand situated next to neighboring countries, which can be divided into 4 groups: the Thai-Myanmar border (10 provinces), the Thai-Cambodia border (6 provinces), the Thai-Lao border (10 provinces) and the Thai-Malaysia border (4 provinces). The purpose of the present study was to describe the pattern and trend of malaria incidence in the highly endemic provinces along the Thai borders for the 11 years from 1991 to 2001.