Intravenous quinidine for the treatment of severe falciparum malaria. Clinical and pharmacokinetic studies

Fatal rooster attack

A 76-year-old woman was attacked by a domestic rooster on her rural property while collecting eggs. The bird pecked her lower left leg causing significant hemorrhage with collapse and death. The decedent's past medical history included treated hypertension, hyperlipidemia, non-insulin dependent diabetes mellitus and varicose veins. At autopsy the major findings were limited to the lower left leg which was covered with adherent dried blood. Two small bleeding lacerations were present, one of which was located immediately over a perforated large varix. Death was therefore due to exsanguination from bleeding varicose veins following an attack by a rooster. This case demonstrates that even relatively small domestic animals may be able to inflict lethal injuries in individuals if there are specific vascular vulnerabilities present.

Permeability of blood-brain barrier in macaque model of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced Parkinson disease

Brain bioavailability of drugs developed to address central nervous system diseases is classically documented through cerebrospinal fluid collected in normal animals, i.e., through an approximation as there are fundamental differences between cerebrospinal fluid and tissue contents. The fact that disease might affect brain availability of drugs is almost never considered at this stage although several conditions are associated with blood-brain barrier damage. Building upon our expertise in Parkinson's disease translational research, the present study addressed this gap comparing plasma and cerebrospinal fluid bioavailability of l-3,4-dihydroxyphenylalanine, carbamazepine, quinidine, lovastatin, and simvastatin, in healthy and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated macaques, the gold standard model of Parkinson's disease. The drugs were selected based upon their differential transport across the blood-brain barrier. Interestingly, brain bioavailability of quinidine was decreased while others were unaffected. Pharmacokinetics and pharmacodynamics experiments of drugs addressing Parkinson's disease might thus be performed in healthy animals unless the drugs are known to interact with the organic cation transporter.

Anti-plasmodial activity of ethanolic extract of root and stem back of Cassia sieberiana DC on mice

AIM

This study assessed within 4 days of suppressive test in vivo antimalarial activity of Ethanolic extract of root and stem bark of Cassia sieberiana DC against chloroquine sensitive strain of Plasmodium berghei NK65 in mice.

METHODOLOGY

Two sets, each of five groups of four mice per each group were used. The groups of animals were administered with 100, 200, and 300 mg extract/kg body weight respectively, while positive control group were administered with 5 mg chloroquine/kg body weight and the negative control, were administered with 5 m1 distilled water/kg body weight. Oral acute toxicity was evaluated using up and down procedure.

RESULT

Both the root and stem bark extract of C. sieberiana showed antimalarial property for suppressive tests. Chemo suppression of the root extract exerted significant (P < 0.05) dose-dependent reduction in the level of parasiteamia of 30.7%, 52.7%, and 55.8%. And from stem extract 17.6%, 38.0%, and 63.9% were recorded on mice when compared with 96.0% suppressive rate obtained from weight of chloroquine. The phytochemical screening of the plants root and stem bark extract revealed the presence of alkaloids, anthraquinones, flavonoids, triterpenoids, tannins, cardiac glycosides, saponins, reducing sugars and carbohydrates. The oral median lethal dose was determined to be >3000 mg/kg body weight.

CONCLUSION

The acute toxicity results of this study showed that the plant parts used are assumed to be safe and has anti-plasmodial activity that can be explored for the management of malaria.

Severe Malaria Complicated by G6PD Deficiency in a Pediatric Tanzanian Immigrant

Approximately 1,500 cases of malaria are diagnosed in the United States each year. Most cases are travelers and immigrants returning from parts of the world where malaria transmission occurs. Malaria is the most frequent cause of systemic febrile illness without localizing symptoms in travelers returning from the developing world, so vigilance by providers is needed when evaluating patients returning from areas in which malaria is endemic. Despite the availability of effective treatment, malaria still accounts for more than 1 million deaths per year worldwide, with rates being disproportionately high in young children under the age of 5. We present the case of a 4-year-old refugee who emigrated from Tanzania with severe malaria due to dual infections of Plasmodium falciparum and P. ovale, whose treatment course was complicated by quinidine gluconate cardiotoxicity and glucose-6-phosphate dehydrogenase deficiency.

Cardiac complications of unwitting co-injection of quinine/quinidine with heroin in an intravenous drug user

Adulterants "cut into" street heroin are common and often not detected by standard urine toxicology screening; however, their unwitting co-injection may have clinical consequences. We report a case of accelerated atrioventricular junctional arrhythmia that we determined to have been caused by quinine/quinidine cut into heroin. While identification and discontinuation of the offending agent helps confirm the diagnosis and is the treatment of choice, this is often complicated by the individual's dependence on the street drug in which the adulterant is mixed. This case highlights the need for clinicians to be aware of common adulterants, to know how to test for them, and to consider them as possible causes of medical complications in individuals who use drugs.

Imported malaria: an update

Evidence suggests that imported malaria is a diagnostic challenge with initial misdiagnosis rates of 40% or greater. Given that prompt diagnosis and appropriate treatment are the only intervention proven to prevent progression to severe malaria and death, these figures are concerning. The purpose of this clinical review is to provide the most up-to-date and practical information on the diagnosis and treatment of imported malaria for the emergency health care provider. We highlight common pitfalls, errors, and mistakes in arriving at the correct diagnosis. We also emphasize the 3 key aspects to avoid progression to severe disease: rapid diagnosis, prompt initiation of treatment, and appropriate choice of antimalarial treatment.

Cardiotoxicity of antimalarial drugs

There are consistent differences in cardiovascular state between acute illness in malaria and recovery that prolong the electrocardiographic QT interval and have been misinterpreted as resulting from antimalarial cardiotoxicity. Of the different classes of antimalarial drugs, only the quinolines, and structurally related antimalarial drugs, have clinically significant cardiovascular effects. Drugs in this class can exacerbate malaria-associated orthostatic hypotension and several have been shown to delay ventricular depolarisation slightly (class 1c effect), resulting in widening of the QRS complex, but only quinidine and halofantrine have clinically significant effects on ventricular repolarisation (class 3 effect). Both drugs cause potentially dangerous QT prolongation, and halofantrine has been associated with sudden death. The parenteral quinoline formulations (chloroquine, quinine, and quinidine) are predictably hypotensive when injected rapidly, and cardiovascular collapse can occur with self-poisoning. Transiently hypotensive plasma concentrations of chloroquine can occur when doses of 5 mg base/kg or more are given by intramuscular or subcutaneous injection. At currently recommended doses, other antimalarial drugs do not have clinically significant cardiac effects. More information on amodiaquine, primaquine, and the newer structurally related compounds is needed.

Are one or two dangerous? Quinine and quinidine exposure in toddlers

Quinine and quinidine have been cited as drugs that may cause significant morbidity and mortality in toddlers who ingest one or two pills. The use of both of these drugs has declined in the United States since the 1980s. A review of the literature and Poison Control data reveals that large quinine and quinidine ingestions, although rare in this country, may lead to severe toxicity and death related to cardiovascular and neurological effects in both children and adults. Although the majority of cases of quinine and quinidine toxicity in toddlers occur after ingestions of more than two pills, a single report each of severe toxicity after the equivalent of an ingestion of two pills or less by a toddler exists for both quinine and quinidine. Although the risk to the toddler exposed to one or two tablets seems to be small, triage to an Emergency Department is warranted after quinidine ingestion of any amount and after quinine ingestion that exceeds the age-appropriate therapeutic dose.

Role of US military research programs in the development of US Food and Drug Administration--approved antimalarial drugs

US military physicians and researchers helped identify the optimum treatment dose of the naturally occurring compound quinine and collaborated with the pharmaceutical industry in the development and eventual US Food and Drug Administration approval of the synthetic antimalarial drugs chloroquine, primaquine, chloroquine-primaquine, sulfadoxine-pyrimethamine, mefloquine, doxycycline, halofantrine, and atovaquone-proguanil. Because malaria parasites develop drug resistance, the US military must continue to support the creation and testing of new drugs to prevent and treat malaria until an effective malaria vaccine is developed. New antimalarial drugs also benefit civilians residing in and traveling to malarious areas.

Management of severe malaria: interventions and controversies

This article emphasizes that for many controversial reasons, severe malaria in travelers differs from that seen in endemic areas. There is no controversy, however, that malaria in individuals living in endemic areas should retain research priority. Some of the questions raised might never be amenable to randomized controlled trials, either because of ethical or logistical restraints. A possibly indulgent wish list of outcome (mortality) studies using currently known treatment modalities, however, includes the loading dose of quinine, vigorous fluid replacement, ET, the artemisinins, mannitol, and N-acetylcysteine in the treatment of severe malaria. There may clearly be many more. The treatment of severe malaria remains a challenge to those with an interest in managing life-threatening disease with complex and fascinating pathophysiology. As challenging as the studies listed previously may seem, however, priority must inevitably be given to research on how one can prevent and treat mild disease in the first place.

The treatment of falciparum malaria

Effective treatment for falciparum malaria has been available for over 300 years, and for most of this time physicians have argued over the best doses and the methods of administering antimalarial drugs. A reasonable consensus has since emerged on the treatment of uncomplicated malaria, but there is still disagreement over the management of severe infections, and as a consequence there have been confusing and dangerous discrepancies in treatment recommendations. In this review, Nicholas White discusses the confusion, offering a rational basis for the clinical treatment of both uncomplicated and severe falciparum malaria.

The treatment of complicated and severe malaria

All cases of falciparum malaria are potentially severe and life threatening, especially when managed inappropriately. A major reason for progression from mild through complicated to severe disease is missed or delayed diagnosis. Once diagnosed, the priority for treatment of complicated and severe disease is the parenteral administration of adequate, safe doses of an appropriate antimalarial, in the setting of the highest possible level of clinical care (i.e. usually an intensive care unit). Supportive management of complications such as coma, convulsions, metabolic acidosis, hypoglycaemia, fluid and electrolyte disturbances, renal failure, secondary infections, bleeding disorders and anaemia is also important. The most recent advance in antimalarial chemotherapy has been the use of artemisinin derivatives especially intravenous artesunate, which may well revolutionize the management of severe disease. Outside antimalarial therapy, mechanical ventilation and renal replacement have also played an important role in reducing mortality of this life-threatening condition.

Cerebral malaria: optimising management

Cerebral malaria is one of the most common nontraumatic encephalopathies in the world. Children living in sub-Saharan Africa bear the brunt of the disease, but cerebral malaria is being seen increasingly in adults throughout the world, including outside malarious areas. There are differences in the clinical presentation and pathophysiology between African children and nonimmune adults from any region. Mortality is high (10-20%). Parenteral antimalarials are the only interventions that have been shown to affect outcome. The cinchona alkaloids (quinine and quinidine) are the mainstay of antimalarial treatment, but the artemisinin derivatives are increasingly being used. Aggressive treatment and prevention of convulsions may be important, particularly in children. Other ancillary treatments that can be used to augment standard antimalarial drugs, such as exchange blood transfusions, osmotic diuretics and pentoxifylline, may improve outcome but have not been subjected to rigorous clinical trials. There is little support for corticosteroids or deferoxamine (desferrioxamine) in cerebral malaria. Other adjuncts have not been adequately tested. Further research is required on drugs that interfere with the pathophysiological processes to prevent neurological complications and death.

The prevention of malaria

Long before the advent of modern chemoprophylaxis drugs, many practitioners successfully prevented the debilitating and fatal outcomes associated with infection by the Plasmodium parasites that cause malaria. Today, with effective insect repellents and several excellent medications available for chemoprophylaxis, there has never been a better array of quality products to prevent mosquito bites and infection and to suppress parasites once in the blood stream; however, there are thousands of imported cases into nonendemic countries and scores of deaths and near-fatal outcomes every year in returning travelers, soldiers, immigrants, and refugees. In this article, the author focuses on practical uses of currently available prevention tools.

Crystal structure of (-)-mefloquine hydrochloride reveals consistency of configuration with biological activity

The absolute configuration of (-)-mefloquine has been established as 11R,12S by X-ray crystallography of the hydrochloride salt, thus allowing comparison of the configuration of mefloquine's optical isomers to those of quinine and quinidine. (-)-Mefloquine has the same stereochemistry as quinine, and (+)-mefloquine has the same stereochemistry as quinidine. Since (+)-mefloquine is more potent than (-)-mefloquine in vitro against the D6 and W2 strains of Plasmodium falciparum and quinidine is more potent than quinine, a common stereochemical component for antimalarial activity is implicated. The crystal of (-)-mefloquine hydrochloride contained four different conformations which mainly differ in a small rotation of the piperidine ring. These conformations are essentially the same as the crystalline conformations of racemic mefloquine methylsulfonate monohydrate, mefloquine hydrochloride, and mefloquine free base. The crystallographic parameters for (-)-mefloquine hydrochloride hydrate were as follows: C17H17F (6)N(2)O(+)Cl(-) .0.25 H2O; M(r), 419.3; symmetry of unit cell, orthorhombic; space group, P2(1)2(1)2(1); parameters of unit cell, a = 12.6890 +/- 0.0006 A (1 A = 0.1 nm), b = 18.9720 +/- 0.0009 A, c = 32.189 +/- 0.017 A; volume of unit cell, 7,749 +/- 4 A(3); number of molecules per unit cell, 16; calculated density, 1.44 g cm(-3); source of radiation, Cu Kalpha (lambda = 1.54178 A); mu (absorption coefficient), 2.373 mm(-1); room temperature was used; final R(1) (residual index), 0.0874 for 3,692 reflections with intensities greater than 2sigma. All of the hydroxyl and amine hydrogen atoms participate in intermolecular hydrogen bonds with chloride ions. The orientation of the amine and hydroxyl groups in (+)-mefloquine may define the optimal geometry for hydrogen bonding with cellular constituents.

In vitro evaluation of quinidine sensitivity in Brazilian Plasmodium falciparum isolates: comparative analysis to quinine and chloroquine

Falciparum malaria represents a serious and an increasing world public health problem due to the acquired parasite's resistance to the most available drugs. In some endemic areas, quinidine, a diastereoisomer of the antimalarial quinine, has been employed for replacing the latter. In order to evaluate the use of quinidine as an alternative to the increasing loss of quinine effectiveness in Brazilian P. falciparum strains, as has been observed in the Amazon area, we have assayed quinidine, quinine and chloroquine. The in vitro microtechnique was employed. All isolates showed to be highly resistant to chloroquine. Resistance to quinine was not noted although high MIC (minimal inhibitory concentration) values have been observed. These data corroborate the decreasing sensitivity to quinine in strains from Brazil. Quinidine showed IC50 from 0.053 to 4.577 micromol/L of blood while IC50 from 0.053 to 8.132 micromol/L of blood was estimated for quinine. Moreover, clearance of the parasitemia was observed in concentrations lower than that used for quinidine in antiarrhythmic therapy, confirming our previous data. The results were similar to African isolate.

Cerebral malaria

Cerebral malaria may be the most common non-traumatic encephalopathy in the world. The pathogenesis is heterogeneous and the neurological complications are often part of a multisystem dysfunction. The clinical presentation and pathophysiology differs between adults and children. Recent studies have elucidated the molecular mechanisms of pathogenesis and raised possible interventions. Antimalarial drugs, however, remain the only intervention that unequivocally affects outcome, although increasing resistance to the established antimalarial drugs is of grave concern. Artemisinin derivatives have made an impact on treatment, but other drugs may be required. With appropriate antimalarial drugs, the prognosis of cerebral malaria often depends on the management of other complications-for example, renal failure and acidosis. Neurological sequelae are increasingly recognised, but further research on the pathogenesis of coma and neurological damage is required to develop other ancillary treatments.

Molecular bases of three characteristic phenotypes of pneumococcus: optochin-sensitivity, coumarin-sensitivity, and quinolone-resistance

Streptococcus pneumoniae is uniquely sensitive to amino alcohol antimalarials in the erythro configuration, such as optochin, quinine, and quinidine. The protein responsible for the optochin (quinine)-sensitive (Opts, Qins) phenotype of pneumococcus is the proteolipid c subunit of the FzeroF1 H(+)-ATPase. OptR/QinR isolates arose by point mutations in the atpC gene and produce different amino acid changes in one of the two transmembrane alpha-helices of the c subunit. In addition, comparison of the sequence of the atpCAB genes of S. pneumoniae R6 (Opts) and M222 (an OptR strain produced by interspecies recombination between pneumococcus and S. oralis), and S. oralis (OptR) revealed that, in M222, an interchange of atpC and atpA had occurred. We also demonstrate that optochin, quinine, and related compounds specifically inhibited the membrane-bound ATPase activity. Equivalent differences between Opts/Qins and OptR/QinR strains, both in growth inhibition and in membrane ATPase resistance, were found. Pneumococci also show a characteristic sensitivity to coumarin drugs, and a relatively high level of resistance to most quinolones. We have cloned and sequenced the gyrB gene, and characterized novobiocin resistant mutants. The same amino acid substitution (Ser-127 to Leu) confers novobiocin resistance on four isolates. This residue position is equivalent to Val-120 of Escherichia coli ryGB, a residue that lies inside the ATP-binding domain but is not involved in novobiocin binding in E. coli, as revealed by crystallographic data. In addition, the genes encoding the ParC and ParE subunits of topoisomerase IV, together with the region encoding amino acids 46 to 172 (residue numbers as in E. coli) of the pneumococcal ryGA subunit, were characterized in respect to fluoroquinolone resistance. The gyrA gene maps to a physical location distant from the gyrB and parEC loci on the chromosome. Ciprofloxacin-resistant (CpR) clinical isolates had mutations affecting amino acid residues of the quinolone resistance-determining region of ParC (low-level CpR), or in both resistance-determining regions of ParC and GyrA (high-level CpR). Mutations were found in residue positions equivalent to Ser-83 and Asp-87 of the E. coli GyrA subunit. Transformation experiments demonstrated that topoisomerase IV is the primary target of ciprofloxacin, DNA gyrase being a secondary one.

Steroids for treating cerebral malaria

BACKGROUND

Cerebral malaria is associated with swelling of the brain. Corticosteroid drugs could reduce the harmful effects of this swelling, but could also suppress host immunity to infection.

OBJECTIVES

This review aimed to assess the effects of steroids in patients with cerebral malaria in relation to survival and long-term disability.

SEARCH STRATEGY

The Cochrane Controlled Trials Register, the Cochrane Infectious Diseases Group Trials Register, existing reviews, and contact with experts in the field.

SELECTION CRITERIA

Randomised controlled trials comparing steroids and no steroids in otherwise identical treatments for patients with cerebral malaria.

DATA COLLECTION AND ANALYSIS

Assessments of inclusion criteria, trial quality and data extraction were done by each author independently. The outcomes sought were death, death with life-threatening complications, other complications, and disability.

MAIN RESULTS

Two trials met the inclusion criteria. Out of a total of 143 patients, there were 30 deaths, distributed evenly between the steroid and the comparator group. The researchers reported clinical complications as the number of events in each trial arm, and did not exclude complications occurring in fatalities. This makes it difficult to interpret the reports of significantly more episodes of gastro-intestinal bleeding and seizures in the steroid group. No studies examined disability.

REVIEWER'S CONCLUSIONS

There is currently no evidence of benefit from steroids in this condition, but the small number of participants means it is difficult to exclude an effect on mortality in either direction. Data on clinical complications are difficult to assess.

Continuous intravenous quinidine infusion for the treatment of atrial fibrillation or flutter: a case series

BACKGROUND

The purpose of the study was to evaluate a continuous intravenous quinidine infusion (CIQI) for the treatment of cardiac arrhythmias in critically ill patients.

METHODS AND RESULTS

A 2-year retrospective review was conducted in adult patients receiving a CIQI for cardiac arrhythmias. Patient demographics, baseline laboratory values, indication for quinidine, dose, duration of therapy, efficacy, adverse events, and serum concentration were among the collected data. All patients were critically ill and receiving quinidine for the treatment of atrial arrhythmias. Quinidine was effective in 14 (61%) of the 23 enrolled patients. Ninety-one percent of the patients received the CIQI after surgery. A total of 8 (35%) patients died. Four (17%) patients had hypotension possibly attributed to the quinidine.

CONCLUSIONS

A continuous intravenous infusion of quinidine gluconate may be effective in patients in whom other agents are contraindicated or have failed. However, as with all antiarrhythmic agents, risks of therapy must be carefully considered.

Comparative cardiac effects of halofantrine and chloroquine plus chlorpheniramine in children with acute uncomplicated falciparum malaria

The cardiac effects of halofantrine (HF) and chloroquine plus chlorpheniramine (CQ-CP), a histamine H1 antagonist which reverses chloroquine insensitivity in Plasmodium falciparum in vitro and in vivo, were assessed in 41 children with acute symptomatic uncomplicated P. falciparum malaria by electrocardiographic and clinical monitoring over a period of 14 days. In addition, the cardiac effects of chloroquine (CQ) alone and CQ-CP were compared in 10 age- and sex-matched children. HF produced a significantly higher proportion of abnormally prolonged P-R interval (8 abnormally prolonged out of 132 total P-R events) than CQ-CP (1 of 133 P-R events) (P = 0.03), but a similar proportion of prolonged Q-Tc interval to that of CQ-CP (46 of 149 versus 29 of 134 events, P = 0.07). Compared with pre-treatment Q-Tc, HF significantly prolonged this interval from 6 to 96 h post treatment with a maximum effect at 24 h after commencing HF treatment. CQ-CP by contrast produced significant changes in Q-Tc values from 6 to only 48 h with a maximum effect at 48 h. HF-induced Q-Tc prolongations were significantly higher than those of CQ-CP only at 24 h. The cardiac effects of CQ-CP were similar to those of CQ alone. Despite the electrocardiogram abnormalities, rhythm disturbance was rare and there was no clinical symptom in any of the treatment groups. Compared with HF, CQ-CP produced cardiac effects that were less severe and in fewer children with acute falciparum malaria. The addition of CP to CQ does not significantly amplify the cardiac effects of CQ in children with acute uncomplicated falciparum malaria.

Neurological manifestations of falciparum malaria

Plasmodium falciparum remains one of the most common causes of central nervous system infection worldwide. Recently, differences between the pathophysiology of cerebral malaria in African children and nonimmune adults have been discovered, new syndromes occurring after malaria infection described, and mechanisms for the pathogenesis proposed. In addition, new antimalarial agents have been examined worldwide and initial studies on supportive studies conducted. This paper reviews these new advances, putting them into the perspective of the more established knowledge.

Malaria

The preeminent infectious threat to unwary tropical travelers, malaria is a preventable, mosquito-borne protozoan infection of red blood cells, which causes fever, anemia, respiratory failure, coma, and death. Malaria is a true medical emergency that requires rapid diagnosis and treatment. Unfortunately, in two thirds of tropical travelers who die of malaria, either treatment is delayed or the diagnosis is simply missed. Every tropical traveler with fever or unexplained, flu-like illness must be assumed to have life-threatening malaria and must have thick and thin blood smears immediately examined to confirm the diagnosis.

Falciparum malaria

Falciparum malaria is one of the most common infectious illnesses in the world and can progress rapidly to coma and death in the nonimmune patient. The presentation is nonspecific, so blood smears must be made and read quickly. Proper therapy requires taking into account drug resistance, recognizing the signs of severe malaria, and proper treatment for complications. Long-sleeved clothing, bed nets, insecticides, and chemoprophylaxis can help prevent malaria, but the infection must be suspected in any traveler returning from an endemic area. This article reviews epidemiology, diagnosis, treatment, and prevention of falciparum malaria in the temperate zone.

[Cerebral malaria and AIDS: case report]

Although it has not been definitely proven that the severity of malaria is associated to human immunodeficiency virus (HIV) we know that infection through Plasmodium falciparum can favor a rapid evolution of the HIV infection. Besides, association of malaria with HIV/AIDS from a clinical point of view can be clinically severe in the face of the occurrence of other microorganisms or neoplasias, which worsens the evolution and prognosis of the affected patients. The concurrence of HIV with Plasmodium in malaria endemic zones is a possibility which should always be taken into consideration, since transmission is related to risk factors caused by people's behavior which are not always promptly revealed and/or identified. The authors report one case of brain malaria infection by Plasmodium vivax and Plasmodium falciparum in a patient with AIDS. They describe the clinical evolution and therapy.

Quinine specifically inhibits the proteolipid subunit of the F0F1 H+ -ATPase of Streptococcus pneumoniae

Streptococcus pneumoniae is uniquely sensitive to quinine and its derivatives, but only those alkaloids having antimalarial properties, i.e., those in the erythro configuration, also possess antipneumococcal activity. Quinine and related compounds inhibit the pneumococcal H+ -ATPase. Quinine- and optochin-resistant pneumococci showed mutations that change amino acid residues located in one of the two transmembrane alpha-helices of the c subunit of the F0F1, H+ -ATPase.

Parasitic infections of the central nervous system in children. Part II: Disseminated infections

In the second segment of this three-part review of parasitic infections of the central nervous system in children, we consider parasitic infections which typically involve various tissues and organs in addition to the brain and spinal cord. Parasites capable of dissemination in immunocompetent hosts are discussed first, and, as in Part I, organisms are grouped according to their predominant geographic location. This is followed by a discussion of the unique aspects of toxoplasmosis, strongyloidiasis and infection with microsporidia in immunocompromised patients, with an emphasis on the central nervous system.

Malaria: review of features pertinent to the emergency physician

Malaria is a health problem of growing concern to the emergency physician. Plasmodium vivax, P ovale, and P malaria infections are relatively benign and can be treated in an outpatient setting with oral chloroquine or amodiaquine. In contrast, P falciparum can present fulminantly, often resulting in death with multiple organ system failure. Although quinine historically has been the mainstay of therapy for severe falciparum malaria in the United States, and still is outside the U.S., quinidine gluconate as a continuous infusion is currently recommended as the agent of choice for severe P falciparum infection. In addition to the rapid administration of appropriate chemotherapeutic agents and the institution of aggressive supportive care, exchange transfusion may be utilized as a means of rapidly reducing the parasitemia and consequently, the mortality.

Diagnosis and treatment of malaria in Britain

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Stereochemical evaluation of the relative activities of the cinchona alkaloids against Plasmodium falciparum

Quinine and quinidine were over 100 times more active than 9-epiquinine and 9-epiquinidine against chloroquine-sensitive Plasmodium falciparum and over 10 times more active against chloroquine-resistant P. falciparum. Since the only structural difference between quinine, quinidine, 9-epiquinine, and 9-epiquinidine is their three-dimensional configuration, the three-dimensional structures of these four alkaloids were examined in order to explain the large difference in relative activities between the 9-epi alkaloids and quinine and quinidine. The crystal structure of 9-epiquinidine hydrochloride monohydrate was determined by X-ray diffraction and was compared with the crystal structures of quinine, quinidine sulfate dihydrate, and 9-epiquinine hydrochloride dihydrate. The crystallographic parameters for 9-epiquinidine hydrochloride monohydrate were as follows: chemical formula, C20H25N2O2+.Cl-.H2O; M(r), 378.9; symmetry of unit cell, orthorhombic; space group, P2(1)2(1)2(1); parameters of unit cell, a was 7.042 +/- 0.001 A (1 A = 0.1 nm), b was 9.082 +/- 0.001 A, c was 31.007 +/- 0.005 A; the volume of unit cell was 1,983.1 +/- 0.6 A3; number of molecules per unit cell was 4; the calculated density was 1.27 g cm-3; the source of radiation was Cu K alpha (lambda = 1.54178 A); mu (absorption coefficient) was 18.82 cm-1; F(000) (sum of atomic scattering factors at zero scattering angle) was 808; room temperature was used; final R (residual index) was 5.72% for 1,501 reflections with magnitude of F(o) greater than 3 sigma (F). The intramolecular distance from N-1 to O-12 in 9-epiquinidine and 9-epiquinine, although shorter than the corresponding distance in quinine and quinidine, was similar to those of other active amino alcohol antimalarial agents. In all four alkaloids, both the hydroxyl and amine groups formed intermolecular hydrogen bonds, showing the potential for forming hydrogen bonds with cellular constituents. However, the positioning of the N+-1--H-N1 and O-12--H-O12 groups relative to each other was quite different in the 9-epi alkaloids versus quinidine. This difference in positioning may determine the relative strengths, of the formation of hydrogen bonds with cellular constituents important to antimalarial activity and, therefore, may determine the relative strength of antimalarial activity.

Acute renal failure in severe chloroquine resistant falciparum malaria

We observed 3 patients with a severe falciparum malaria infection. Although the patients appeared not to be seriously ill on admission, severe complications occurred. Renal impairment was a prominent feature and haemodialysis was sometimes necessary. Many hypotheses have been proposed regarding the aetiology of renal failure in Plasmodium falciparum but cannot yet be fully substantiated. Whatever the aetiology of renal failure might be, we believe that treatment should not differ essentially from that of acute tubular necrosis after circulatory shock and early diagnosis and treatment is imperative in spite of an initially ostensibly good clinical condition.

The influence of alpha 1-acid glycoprotein on quinine and quinidine disposition in the rat isolated perfused liver preparation

We have studied the effect of 0.5 and 2.0 g L-1 of alpha 1-acid glycoprotein (AAG) on the disposition of quinine and quinidine in the rat isolated perfused liver preparation. The higher concentration of AAG (2.0 g L-1) resulted in a significant decrease in clearance [quinine study (control: 9.6 +/- 2.9 vs test: 3.1 +/- 1.2 mL min-1); quinidine study (control: 9.8 +/- 2.4 vs test: 3.5 +/- 1.1 mL min-1]) and volume of distribution [quinine study (control: 1198 +/- 416 vs test: 466 +/- 95 mL); quinidine study (control: 1352 +/- 459 vs test: 317 +/- 24 mL]) but not the elimination half-life compared with control. At the lower concentration (0.5 g L-1) of AAG there was no significant difference in clearance, volume of distribution and elimination half-life for either drug compared with control. By increasing the concentration of AAG from 0.5 to 2.0 g L-1 both the hepatic extraction ratio and the fraction of drug unbound when compared with controls significantly decreased by about 66 and 60% for quinine, and by 65 and 58% for its diastereoisomer quinidine, respectively. The consequence of these changes is a substantial increase in the total quinine (or quinidine) concentrations without any change in the free quinine (or quinidine) concentrations. However, at 0.5 g L-1 AAG compared with control, no significant difference was observed in fraction of drug unbound, extraction ratio, total drug concentration or free drug concentration for either drug. In summary, changing concentrations of AAG, an important binding protein for quinine and quinidine, can affect the hepatic disposition of both drugs.

Disposition of the diastereoisomers quinine and quinidine in the ovine fetus

The disposition of the diastereoisomers quinine and quinidine was investigated in the near-term pregnant ewe. Five sheep were administered quinine and quinidine separately in random order by a combination of bolus and 30-h iv infusion. On a subsequent occasion, four of the five sheep were also administered the two drugs simultaneously. After separate dosage, systemic clearance of quinine tended to be greater than that of quinidine (714 +/- 299 versus 422 +/- 146 mL/min, p = 0.08). Maternal renal clearance exhibited no stereoselectivity and represented less than 2% of total clearance. Simultaneous administration did not alter the disposition of either drug in the mother. After separate dosage, fetal total concentrations (Cf) of quinine and quinidine were substantially lower than maternal total concentrations, as reflected in Cf:Cm ratios of 0.15 +/- 0.06 versus 0.10 +/- 0.08, respectively. Similarly, fetal unbound concentrations (Cfu) were substantially lower than maternal unbound concentrations (Cmu; Cfu/Cmu = 0.46 +/- 0.09 for quinine and 0.23 +/- 0.09 for quinidine). This indicates the presence of fetal elimination of both isomers. Fetal renal clearances of quinine and quinidine were similar (0.34 +/- 0.24 mL/min versus 0.38 +/- 0.24 mL/min) and less than that of endogenous creatinine, indicating the absence of net renal tubular secretion. After simultaneous dosage of quinine and quinidine, Cf:Cm (0.48 +/- 0.24 and 0.31 +/- 0.19, respectively) and Cfu:Cmu (0.73 +/- 0.14 and 0.52 +/- 0.20, respectively) were greater than for separate dosages. Fetal renal clearance of both drugs was unchanged, suggesting that the higher Cfu:Cmu ratios after simultaneous dosage were due to mutual inhibition of the fetal metabolism of these drugs.

Cerebral malaria in children

Cerebral malaria is a rapidly progressive encephalopathy with up to 50% mortality. A cardinal feature is the massing of red cells containing mature Plasmodium falciparum within the cerebral capillaries. Adhesion of these parasitised red cells to endothelium, an event which may initiate cerebral malaria, is being studied at the molecular level. However, the relevance of these studies to the pathophysiology and treatment of human cerebral malaria is uncertain. Although chloroquine is still widely used to treat falciparum malaria, resistance has spread to most of the endemic zone. Quinine is emerging as the only effective treatment for cerebral malaria, though resistance to this drug threatens to become a problem. Alternative drugs are urgently needed.