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P Chanthavanich

Publications and source records attributed to P Chanthavanich.

53 records · Page 3Linked to original sources
PubMed1986

Clinical significance of venom antigen levels in patients envenomed by the Malayan pit viper (Calloselasma rhodostoma).

Serial venom antigen levels were measured by enzyme-linked immunosorbent assay (ELISA) in 46 patients with systemic envenoming by the Malayan pit viper (Calloselasma rhodostoma), a major cause of snake bite in Southeast Asia. The principal effects of the venom are defibrination, hemorrhage and local tissue necrosis. Admission venom levels, which varied between 0 and 595 ng/ml, correlated with the incidence of spontaneous systemic bleeding, blood incoagulability and concentrations of plasma fibrinogen and serum fibrin degradation products. The presence or absence of nonclotting blood also correlated with the time elapsed between the bite and hospital admission. The development of nonclotting blood may be delayed by up to 72 hr after the bite even though circulating venom and raised FDP may be detected at presentation. This is probably explained by a temporary equilibrium between synthesis and consumption of fibrinogen. Venom antigenemia recurred in 12 patients (26%) suggesting continuous absorption of venom from the wound or saturation of extravascular binding sites. Admission venom levels also correlated with the extent of local swelling and the occurrence of tissue necrosis at the site of the bite. Venom was detected in 87% of wound aspirates and 88% of urine specimens taken on admission. Tourniquets, of the type used in rural Thailand, did not delay the absorption of venom into the circulation.

Adolescent↗
PubMed1985

Economical multiple-site intradermal immunisation with human diploid-cell-strain vaccine is effective for post-exposure rabies prophylaxis.

An economical post-exposure regimen of Mérieux human diploid-cell-strain vaccine (HDCSV) was compared with Semple vaccine (SV), the most widely used vaccine in Asia. 155 patients bitten by animals proved to be rabid received either conventional courses of SV (34 severe and 43 mild cases) or HDCSV, 0.1 ml intradermally, at eight sites on day 0, at four sites on day 7, and at one site on days 28 and 91 (36 severe and 42 mild cases). All severely bitten patients were given equine anti-rabies serum (EARS), 80 IU/kg on day 0. There were no deaths from rabies in either group. Follow-up was 97.5% at 1 year and 93% at 2 years. 88% of patients given HDCSV alone had detectable neutralising antibody on day 7 in contrast to 2% given SV alone. Antibody persisted until 1 year in all sera tested from HDCSV patients in contrast to only 48% of SV sera. The high dose of EARS resulted in pronounced suppression of response to HDCSV. There were no serious systemic side-effects but local side-effects were significantly more common in the SV group. The multiple-site intradermal HDCSV regimen was at least as effective as SV. The amount of HDCSV used was 30% of the conventional dose.

Adolescent↗
PubMed1985

Pathophysiological and prognostic significance of cerebrospinal-fluid lactate in cerebral malaria.

Cerebrospinal-fluid (CSF) lactate concentrations were elevated in all but 1 of 45 patients with cerebral malaria. They were significantly higher in patients who died (9.0 +/- 5.3 mmol/l, mean +/- SD) than in survivors (3.4 +/- 1.1 mmol/l, p = 0.0002) and had returned to normal values in each of 9 patients studied after recovery of consciousness. There was a significant negative correlation between CSF lactate and CSF glucose. All 11 patients with CSF lactate concentrations above 6 mmol/l died. CSF lactate is thus an important prognostic indicator in cerebral malaria and these findings suggest that hypoxia contributes to the pathogenesis of this disorder.

Adolescent↗
PubMed1985

Pharmacokinetics of primaquine in man. II. Comparison of acute vs chronic dosage in Thai subjects.

We have investigated the pharmacokinetics of primaquine after acute and chronic administration of the drug to five healthy Thai volunteers. After acute dosage (15 mg p.o.) mean (+/- s.d.) peak plasma concentrations of 65.0 +/- 34.7 ng ml-1 were achieved within 2 +/- 1h. Thereafter plasma drug concentrations declined monoexponentially with a mean elimination half life of 4.4 +/- 1.4 h. The mean (+/- s.d.) oral clearance was 37.6 +/- 15.5 1 h-1. These values are in broad agreement with values obtained in healthy Caucasians after administration of an equivalent dose of primaquine. Repeated dosing with primaquine had no effect on the mean pharmacokinetic parameters calculated for this drug. In contrast, individual pharmacokinetic parameters for some subjects exhibited gross and unpredictable changes after chronic dosage. The carboxylic acid metabolite of primaquine accumulated in plasma after repeated dosing such that by day 14 of chronic dosing the mean AUC (0,24) for this metabolite was 74% greater than that obtained after acute administration of primaquine.

Humans↗
PubMed1985

Intragastric mefloquine is absorbed rapidly in patients with cerebral malaria.

Mefloquine has proved effective in chloroquine- and quinine-resistant falciparum malaria, but it cannot be given parenterally. We have measured the absorption of mefloquine hydrochloride suspension (mean 15.6, range 9.7-28.6 mg/kg) given by nasogastric tube to 19 cerebral malaria patients already receiving intravenous quinine. Absorption was rapid with both dose schedules used; mean absorption half-times were 1.5 and 1.8 hr, and plasma mefloquine concentrations exceeded 200 ng/g within 3 hr of completing administration in all but one exceptionally ill patient who died 40 hr later. Steady state plasma concentrations over 7 days ranged from 300 to 1,050 (mean 561) ng/g. Bioavailability of mefloquine suspension in cerebral malaria therefore appears to be adequate for treatment in all but the most severely ill patients. Although intragastric mefloquine cannot now be recommended as an alternative to intravenous quinine for the treatment of severe chloroquine-resistant falciparum malaria, this situation could change if quinine resistance increases further.

Absorption↗
PubMed1985

Lack of interferon induction in man by two rabies tissue culture vaccines.

Both neutralising antibody and interferon play a part in protection of animals against death from rabies virus infection. Interferon induction was therefore sought in 53 volunteers within 24 hours of receiving human diploid cell strain vaccine or fetal bovine kidney cell vaccine given either intramuscularly or intradermally. Repeat observations were made in 18 subjects following a second dose of vaccine seven days later. No interferon was detected in any sample tested although no subject had any detectable rabies neutralising antibody on day 0. The sensitivity of the interferon assay, and comparison with other studies are discussed. An interferon inducer suitable for human use should be sought as an alternative to, or a replacement for, passive rabies immunization.

Adolescent↗
PubMed1984

Multi-site intradermal and multi-site subcutaneous rabies vaccination: improved economical regimens.

Neutralising antibody responses to six post-exposure regimens of human diploid cell strain rabies vaccine with or without human rabies immune globulin (HRIG) were studied in 98 patients. The total amount of vaccine used was 22-34% of that required by conventional regimens. Vaccine was given at multiple sites intradermally or subcutaneously with or without adjuvant. Antibody was detectable within 7 days of the first dose in all subjects only in the groups given 0.1 ml intradermally at 8 sites. From day 14 onwards all groups showed an excellent antibody response; there was little difference between the various regimens. Suppression of the response to 8-site intradermal vaccination by a large dose of HRIG could be prevented by giving the second dose of vaccine on day 7 rather than day 14.

Adjuvants, Immunologic↗
PubMed1983

Severe hypoglycemia and hyperinsulinemia in falciparum malaria.

We studied the occurrence, clinical manifestations, and mechanism of hypoglycemia in patients with falciparum malaria in eastern Thailand. Hypoglycemia, which was often severe and recurrent, occurred in 17 patients, including 12 in a series of 151 patients with cerebral malaria. Thirty episodes were investigated. Plasma concentrations of insulin and C peptide were inappropriately high, and lactate and alanine concentrations were significantly higher than in patients with falciparum malaria who were normoglycemic (P less than 0.05). Sixteen patients had received quinine; plasma quinine and insulin concentrations were correlated at the time of hypoglycemia (P = 0.007). In seven healthy fasting volunteers intravenous quinine increased the mean plasma insulin concentration (+/- S.D.) from 8.9 +/- 3.1 to 17.1 +/- 8.4 mU per liter (P = 0.02) and reduced the mean plasma glucose concentration from 88 +/- 20 to 68 +/- 23 mg per deciliter (P = 0.002). Our observations indicate that in falciparum malaria quinine-induced insulin secretion may precipitate hypoglycemia, but other factors, including the large glucose requirements of the malaria parasites may also contribute. This important complication, associated with pregnancy and severe disease, must be excluded in all patients with falciparum malaria who have impaired or deteriorating consciousness.

3-Hydroxybutyric Acid↗
PubMed1983

Do patients with cerebral malaria have cerebral oedema? A computed tomography study.

Computed tomography of the brain in 10 patients with severe cerebral malaria, 5 of whom died, showed evidence of cerebral oedema in only 2 fatal cases. Small areas of altered density were seen in 4 cases; these were not associated with focal neurological signs and were still visible in convalescent scans in 2 survivors. 4 patients, including 1 of the fatalities, had completely normal scans. Cerebral oedema may occur in severe cerebral malaria but is not a consistent feature of living patients and cannot, therefore, always be the cause of their coma.

Acute Disease↗
PubMed1983

Quinine disposition kinetics.

Intravenous quinine dihydrochloride (5 mg kg-1 over 5 min) was given to seven healthy male volunteers. There were minor subjective symptoms in all subjects but no significant changes in pulse or blood pressure. There was significant prolongation of the electrocardiographic QRS and rate corrected QT intervals which was greatest between 1 and 4 min after completion of the quinine infusion. Values then returned towards baseline. Plasma concentrations of quinine were measured spectrophotofluorimetrically after benzene extraction. Peak plasma concentrations (mean +/- 1 s.d.) after the infusion were 5.1 +/- 1.3 mg 1(-1). Pharmacokinetic analysis fitted a two compartment open model in each case; distribution half-time (t 1/2, lambda 1) was 1.89 +/- 0.54 min (mean +/- 1 s.d.), elimination half-time (t 1/2, z) 11.1 +/- 2.1 h, apparent volume of the central compartment (V1) 0.57 +/- 0.32 1 kg-1, total apparent volume of distribution 1.80 +/- 0.37 1 kg-1 and total clearance 1.92 +/- 0.45 ml min-1 kg-1.

Adolescent↗
PubMed1983

Quinine loading dose in cerebral malaria.

In cerebral malaria, the use of currently recommended doses of intravenous quinine may result in subtherapeutic plasma concentrations during the critical first 24 hours of treatment. A loading dose of quinine (20 mg/kg quinine dihydrochloride, equivalent to 16.7 mg/kg base, infused over 4 hours) proved a rapid and safe method of achieving plasma concentrations above the high minimum inhibitory concentrations for Plasmodium falciparum prevalent in Eastern Thailand.

Adolescent↗
PubMed1983

Retinal hemorrhage, a common sign of prognostic significance in cerebral malaria.

Retinal hemorrhages were seen in 21 patients among a group of 144 with strictly-defined cerebral malaria. Hemorrhages were multiple in 17 cases and bilateral in 14. There was subhyaloid extension in two. Soft exudates were seen in two, the retinae were considered edematous in four and in one there was bilateral papilledema. Retinal hemorrhages were significantly associated with several indices of severity of Plasmodium falciparum infection: high parasitemia with schizontemia, anemia, elevated serum creatinine and reduced plasma antithrombin III. Only two patients with hemorrhages were both severely anemic and thrombocytopenic. It is suggested that retinal hemorrhages, a frequent finding in cerebral malaria, may be visible evidence of vascular lesions involved in the pathogenesis of this condition.

Adolescent↗
PubMedDate not supplied

Arboreal green pit vipers (genus Trimeresurus) of South-East Asia: bites by T. albolabris and T. macrops in Thailand and a review of the literature.

In Thailand 29 patients were proved to have been bitten by arboreal green pit vipers: 24 by Trimeresurus albolabris and 5 by T. macrops. They were studied in order to define the clinical effects of envenoming, to characterize the haemostatic abnormalities and assess the efficacy of Thai Red Cross antivenom. T. macrops caused only local painful swelling, neutrophil leucocytosis and thrombocytopenia. T. albolabris caused more severe envenoming with local blistering and necrosis, shock, spontaneous systemic bleeding, defibrination, thrombocytopenia and leucocytosis. There was no evidence of disseminated intravascular coagulation, but fibrinolytic activity was increased. Platelet function was normal. The product of admission venom antigen concentration and the delay between bite and admission was significantly higher in defibrinated patients than in those without severe coagulopathy. Antivenom (5 ampoules intravenously) restored blood coagulability, but there was persistent venom antigenaemia, associated in some cases with recurrent coagulopathy. The literature on bites by south Asian green pit vipers of the genus Trimeresurus is reviewed; these bites are common medical problems and causes of morbidity. The identification of individual species is difficult, but may be important if antivenom is to be improved and used appropriately.

Adolescent↗
PubMedDate not supplied

Efficacy and pharmacokinetics of atovaquone and proguanil in children with multidrug-resistant Plasmodium falciparum malaria.

A trial was conducted in 32 Thai children with uncomplicated multidrug-resistant falciparum malaria to assess the efficacy, safety and pharmacokinetics of atovaquone and proguanil; plasma concentrations of atovaquone, proguanil and its metabolite, cycloguanil, were measured in a subset of 9 children. The children received atovaquone (17 mg/kg/d for 3 d) plus proguanil (7 mg/kg/d for 3 d). Twenty-six children who had only Plasmodium falciparum infection and remained in hospital for 28 d were assessed for drug efficacy. The combination regimen produced a cure rate of 100%. Parasite and fever clearance times were 47 h (range 8-75) and 50 h (range 7-111), respectively. Atovaquone and proguanil were rapidly absorbed, with median time to peak concentrations of 6 h (range 6-24) and 6 h (range 6-12), respectively. Peak concentrations of cycloguanil were achieved between 6 and 12 h (median 6) after administration of proguanil. Mean peak plasma concentration of atovaquone on day 3 was 5.1 micrograms/mL (SD = 2.1). The day 3 mean peak plasma concentration of proguanil was 306 ng/mL (SD = 108) compared with 44.3 ng/mL (SD = 27.3) for cycloguanil. Mean values for the AUC (area under plasma concentration-time curve) were 161.8 micrograms/mL.h (SD = 126.9) for atovaquone, 4646 ng/mL.h (SD = 1226) for proguanil, and 787 ng/mL.h (SD = 397) for cycloguanil. Terminal elimination half-lives of atovaquone, proguanil and cycloguanil were estimated as 31.8 h (SD = 8.9), 14.9 h (SD = 3.3) and 14.6 h (SD = 2.6), respectively. No major adverse effect was attributable to the study drugs. Atovaquone/proguanil combination is safe and highly effective, and should be especially valuable for treatment of multidrug-resistant falciparum malaria.

Antimalarials↗