Failure of chloroquine-erythromycin and chloroquine-tetracycline combinations in treatment of chloroquine-resistant falciparum malaria in eastern Thailand

In Eastern Thailand the increasing resistance of Plasmodium falciparum to all available antimalarial drugs prompted a reassessment of chloroquine in combination with either erythromycin or tetracycline. Both combinations had produced encouraging results in vitro, in experimental animal models, or in preliminary clinical trials. In patients with uncomplicated falciparum malaria presenting with moderate parasitaemia the trial of chloroquine and tetracycline was abandoned after RIII resistance with clinical deterioration was encountered in 2 out of the first 5 patients studied. Of 16 patients treated with chloroquine+erythromycin, 11 showed resistance (RI-RIII). These regimens appear ineffective and potentially dangerous in Eastern Thailand.

Plasmodium yoelii: blood oxygen and brain function in the infected mouse

The carriage of oxygen by the blood and the in vivo response of the brain were investigated in mice infected with a lethal strain of Plasmodium yoelii. All mice with parasitaemia exceeding 70% were severely anaemic (Hb 3.5 +/- 1.8 g/dl; mean +/- 1 SD), acidotic (blood pH 7.04 +/- 0.06) and hypoglycaemic (blood glucose 0.6 +/- 0.76 mumol/ml). The oxyhaemoglobin dissociation curve (ODC) of blood from heavily infected mice was shifted right as compared to controls, but the increase in p50 was less than expected from the accompanying acidosis. The reduced shift right was due to a decrease in the 2,3-DPG/Hb ratio in infected animals (0.72 +/- 0.12, n = 17 vs 1.10 +/- 0.09, n = 12 in controls). Despite the severity of terminal infection, the cerebral pH and the relative steady-state concentrations of PCr, ATP and Pi measured in vivo by nuclear magnetic resonance (31P NMR) were normal. Alterations in brain energy status and pH cannot account for cerebral signs or death in this proposed mouse model of cerebral malaria.

Cardiovascular abnormalities in osteogenesis imperfecta

To investigate the prevalence of cardiac abnormalities in osteogenesis imperfecta we performed a clinical and echocardiographic study on 20 patients. One patient had aortic regurgitation, 13 had soft late apical systolic murmurs (without significant mitral regurgitation), and seven had systemic hypertension. In only one patient was there echocardiographic evidence of mitral valve prolapse. The aortic root diameter exceeded the normal range in six patients, two of whom were hypertensive. The overall mean value (+/- 1 S.D.) in the 16 patients without marked skeletal deformity was 2.02 +/- 0.33 cm/m2. The echocardiographic appearances suggested that the left-sided valve cusps were thin, and in 13 patients the aortic valve leaflets showed a coarse systolic flutter.

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.

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.

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.

Red cell quinine concentrations in falciparum malaria

Red cell concentrations of quinine were measured in cerebral malaria and in uncomplicated falciparum malaria both in the acute stage and 1 month after recovery. Red cell quinine elimination half times were significantly shorter than the corresponding plasma half times in cerebral malaria and convalescent uncomplicated cases (P less than 0.001), but not in acute uncomplicated cases (P = 0.12). The ratio of red cell:plasma concentration fell progressively from the 2nd day (0.49) to the 6th day (0.26) of treatment. On admission this ratio was positively correlated with the blood parasite count (P = 0.02). Red cell quinine concentration may be relevant to the assessment of drug resistance, and to the design of treatment regimens.

Meptazinol diminishes the Jarisch-Herxheimer reaction of relapsing fever

Naloxone, an opioid antagonist, and meptazinol, an opioid antagonist with agonist properties, were tested in a double-blind placebo-controlled trial in 24 Ethiopian patients with louse-borne relapsing fever. The potentially fatal Jarisch-Herxheimer reaction (J-HR), which invariably follows tetracycline treatment of the disease, was unaffected by naloxone, 30-40 mg intravenously, but was diminished by meptazinol, 300-500 mg intravenously. Compared with naloxone and placebo, meptazinol reduced the clinical severity of the reaction, significantly delayed and shortened its chill phase, delayed the rise in temperature, and reduced peak temperature and changes in pulse and respiratory rates and leucocyte count. High-dose corticosteroids given before or at the time of tetracycline treatment failed to alter the reaction, which is thought to result from release of endotoxin-like substances. Meptazinol is the first effective treatment for the J-HR of louse-borne relapsing fever. This finding suggests a role for endogenous opioids in the pathogenesis of the J-HR.

Quinine and quinidine: a comparison of EKG effects during the treatment of malaria

We recorded electrocardiograms from 31 patients receiving quinine and 14 patients receiving quinidine for the treatment of Plasmodium falciparum malaria. Despite plasma quinine concentrations of up to 20 mg/L, there was no evidence of cardiotoxicity. QT prolongation was considerably greater in the quinidine-treated patients. The mean ratio of change in corrected QT interval to change in plasma concentration (delta QTc%/delta CQ) was 3.2% . mg-1 . L-1 for quinidine, compared to 0.74% . mg-1 . L-1 for quinine (p less than 0.001). T-wave flattening was observed in both groups. Plasma concentrations of quinine cannot be predicted from the EKG, because concentrations within the therapeutic range produced only minor and unpredictable abnormalities.

Severe neurotoxic envenoming by the Malayan krait Bungarus candidus (Linnaeus): response to antivenom and anticholinesterase

Five patients were bitten by the Malayan krait Bungarus candidus (Linnaeus) in eastern Thailand or north western Malaya. Two patients were not envenomed but the other three developed generalised paralysis which progressed to respiratory paralysis in two cases, one of which ended fatally. One patient showed parasympathetic abnormalities. Anticholinesterase produced a dramatic improvement in one patient. Another patient probably benefited from paraspecific antivenom. The efficacy of antivenoms and adjuvants such as anticholinesterases in patients with neurotoxic envenoming requires further study.

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.

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.

Quinine pharmacokinetics and toxicity in cerebral and uncomplicated Falciparum malaria

Acute pharmacokinetics of intravenously infused quinine were studied in 25 patients with cerebral malaria and 13 with uncomplicated falciparum malaria. In patients with cerebral malaria receiving the standard dose of 10 mg/kg every eight hours, plasma quinine concentrations consistently exceeded 10 mg/liter, reaching a peak 60 +/- 25 hours (mean +/- 1 S.D.) after treatment was begun and then declining. Quinine total clearances (Cl) and total apparent volumes of distribution (Vd) were significantly lower than in uncomplicated malaria (Cl, 0.92 +/- 0.42 compared with 1.35 +/- 0.6 ml/min/kg, p = 0.03; Vd, 1.18 +/- 0.37 compared with 1.67 +/- 0.34 liter/kg, p = 0.0013). There was no significant difference between the two groups in elimination half-times (t/2) or renal clearances (Cu) (t/2, 18.2 +/- 9.7 compared with 16 +/- 7.0 hours; Cu, 0.21 +/- 0.16 compared with 0.21 +/- 0.08 ml/min/kg). In nine patients studied following recovery, Cl (3.09 +/- 1.18 ml/min), Vd (2.74 +/- 0.47 liter/kg), and Cu (0.53 +/- 0.22 ml/min/kg) were significantly greater (p less than or equal to 0.0004), and t/2 was significantly shorter (11.1 +/- 4.1 hours, p = 0.006) than during the acute illness. Cu accounted for approximately 20 percent of Cl in all groups. Renal failure did not alter the disposition kinetics in cerebral malaria. There was no clinical or electrocardiographic evidence of cardiotoxicity and no permanent neurotoxicity. Quinine toxicity in cerebral malaria has probably been overemphasized. The benefits of high plasma concentrations in the acute phase of this life-threatening disease appear to outweigh the risks, particularly in view of the increasing resistance of Plasmodium falciparum to quinine in Southeast Asia.

Quinidine in falciparum malaria

Fourteen patients with falciparum malaria were successfully treated with oral quinidine. Twelve of these patients were followed for 35 days without recrudescence. In six patients the infection had already recrudesced after antimalarial treatment, which in two cases had included a full course of quinine. Quinidine caused no cardiotoxicity, although the electrocardiogram QTc interval was prolonged by more than 25% in four patients. In-vitro cultures from nine of these patients and a further seven patients with falciparum malaria showed that the minimum inhibitory concentration was consistently lower for quinidine than for quinine. Quinidine is an effective antimalarial drug for Plasmodium falciparum infections and may be more potent than quinine.

Arteritis of the arms

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Senile parkinsonism, a study of current treatment

In a survey of all 2069 in-patients at 14 geriatric centres, 249 patients were found to have received drugs for the treatment of parkinsonism. There was a wide variation in point prevalence which varied from 4.6% to 22.6% between centres. Levodopa, usually in combination with a decarboxylase inhibitor, was the most frequently prescribed drug. Compared with the recommendations for its use in Parkinson's diseases, over 75% of patients received inadequate and widely spaced doses. Furthermore, dopamine antagonists were concurrently prescribed to one-third of patients who received levodopa. There was a high incidence of treatment failure (30%), and a low incidence of drug-induced dyskinesia (3%). Dementia was closely associated with the onset of parkinsonism. These findings suggest that many of these patients did not have Parkinson's disease but rather rigid-akinetic syndromes associated with degenerative brain disease. The treatment of parkinsonism in the elderly requires reevaluation.

Captopril and frusemide in severe drug-resistant hypertension

10 patients with severe refractory hypertension were treated with captopril and frusemide. All patients had uncontrolled blood pressure (mean arterial pressure > 140 mm Hg), and 7 had developed accelerated hypertension despite maximum conventional treatment. Captopril and frusemide controlled blood pressure in all 10 patients, without side effects in 9. There was a significant rise in plasma-potassium in 9 patients (1 mmol/l), and hyperkalaemia (plasma-potassium > 6 mmol/l) developed in 3 patients despite coincident treatment with frusemide.