Significant reduction in chloroquine bioavailability following coadministration with the Sudanese beverages Aradaib, Karkadi and Lemon

A review of the effectiveness of hibiscus for treatment of metabolic syndrome

ETHNOPHARMACOLOGICAL RELEVANCE

Hibiscus species (Family: Malvaceae) have long been used in traditional medicine to treat a variety of maladies such as abscesses, bilious conditions, cancer, cough, fatigue, gastrointestinal discomfort, fever, veisalgia, cardiovascular disorders, neurosis, scurvy, and urinary tract disorders. Its antioxidants have the capacity to destroy free radicals that damage cells and increase risk of inflammatory conditions such as metabolic syndrome, cancer, and cardiovascular disease.

AIM OF THE STUDY

This review synthesizes findings from animal studies and clinical trials to assess effectiveness of hibiscus for treating biomarkers of metabolic syndrome including hyperglycemia, hypertriglyceridemia, low high-density lipoprotein, obesity, and hypertension.

MATERIALS AND METHODS

We searched for 12 edible species of hibiscus in the Google Scholar database. Each scientific name of these species, their common names and their edible plant parts were searched in conjunction with fourteen key words associated with metabolic syndrome. A total of 68 articles met all inclusion criteria for this review, including 18 that tested human subjects, 48 that tested other animals, one that tested humans and other animals, and one that did not specify.

RESULTS

Hibiscus often improved blood glucose, total cholesterol, high-density lipoprotein cholesterol, triglycerides, blood pressure, weight, lipid absorption and oxidation of fatty acids within vital organs around the abdominal cavity. Higher doses led to greater benefits in some cases, especially for body mass of animals, but lower doses were often equally effective. Hibiscus was often equally or more effective than pharmaceuticals in improving some biomarkers of metabolic syndrome, especially blood glucose and insulin sensitivity.

CONCLUSION

Hibiscus shows great promise for improving biomarkers of metabolic syndrome, but there are limitations that need to be addressed by future work, including increasing the number and size of human clinical trials, expanding human trials to include people from a greater diversity of ethnicities, taking into account the health and physical activity of human participants, investigating the influence of growing conditions and extraction/preparation techniques on nutrients in hibiscus, comparing the efficacy of several plant parts and plant products of hibiscus to a reference control group within the same experiment, incorporating rigorous statistical analysis of treatments and investigating the influence of dosage.

Pharmacokinetics and Pharmacological Properties of Chloroquine and Hydroxychloroquine in the Context of COVID-19 Infection

Chloroquine and hydroxychloroquine are quinoline derivatives used to treat malaria. To date, these medications are not approved for the treatment of viral infections, and there are no well‐controlled, prospective, randomized clinical studies or evidence to support their use in patients with coronavirus disease 2019 (COVID‐19). Nevertheless, chloroquine and hydroxychloroquine are being studied alone or in combination with other agents to assess their effectiveness in the treatment or prophylaxis for COVID‐19. The effective use of any medication involves an understanding of its pharmacokinetics, safety, and mechanism of action. This work provides basic clinical pharmacology information relevant for planning and initiating COVID‐19 clinical studies with chloroquine or hydroxychloroquine, summarizes safety data from healthy volunteer studies, and summarizes safety data from phase II and phase II/III clinical studies in patients with uncomplicated malaria, including a phase II/III study in pediatric patients following administration of azithromycin and chloroquine in combination. In addition, this work presents data describing the proposed mechanisms of action against the severe acute respiratory distress syndrome coronavirus–2 and summarizes clinical efficacy to date.

Pharmacokinetic Herb-Drug Interaction between Hibiscus sabdariffa Calyces Aqueous Extract and Captopril in Rats

Hibiscus sabdariffa L. (Malvaceae) is a traditional medicinal herb widely consumed as a beverage (“hibiscus tea”), and its global popularity is expanding due to health benefits such as blood pressure and cholesterol control. Previous studies showed that Hibiscus sabdariffa is coadministered with antihypertensives and antihyperlipidemics, thus predisposing herb-drug interactions. We investigated the pharmacokinetic interaction between H. sabdariffa L. aqueous extract and captopril, a frequently prescribed antihypertensive. In this study, chemical profile of H. sabdariffa L. aqueous extract was identified using HPLC system equipped with a DAD detector at 360 nm and 520 nm. The male Sprague Dawley rats were divided into two groups of six rats. Group I received a single dose of captopril suspension (4.5 mg/200 g body weight (BW) orally (p.o.)) while group II received H. sabdariffa L. aqueous extract (60 mg/200 g BW; p.o.) daily for two weeks prior to the same captopril dose. Multiple blood samples were collected at predetermined times after captopril administration and the plasma concentration was analyzed using ultrahigh-pressure liquid chromatography-tandem mass spectrometry. Chemical profiling of the H. sabdariffa L. aqueous extract showed that the extract contains chlorogenic acid, myricetin 3-arabinogalactoside, 5-O-caffeoylshikimic acid, quercetin 3-rutinoside, delphinidin 3-sambubioside, and cyanidin 3-sambubioside. Ingestion of the extract significantly reduced the captopril area under the curve (AUC)_0−t (0.1745 (0.1254–0.2429)), AUC0_−∞ (0.1734 (0.1232–0.2442))], and peak plasma concentration (0.2119 (0.1337–0.3359)) (geometric mean ratio of the coadministration group to the captopril group (90% CI)). The geometric mean ratios were falling outside the 90% CI of 0.8–1.25 bioequivalent range. Conversely, H. sabdariffa L. extract increased the apparent total body clearance (Cl/F, 0.0257 ± 0.0115 vs. 0.1418 ± 0.0338 mL/h·kg) and the apparent volume of distribution (Vd/F, 0.0541 ± 0.0226 vs. 0.3205 ± 0.0790 mL/kg). This study indicated that coadministration of H. sabdariffa L. aqueous extract could change the pharmacokinetic profile of captopril; therefore, its coadministration should be avoided.

Herb-drug interactions: a mechanistic approach

In India, traditional herbal medicines have been an essential part of therapy for the last centuries. However, a large portion of the general populace is using these therapies in combination with allopathy lacking a proper understanding of possible interactions (synergistic or antagonistic) between the herbal product and the allopathic drug. This is based on the assumption that herbal drugs are relatively safe, i.e. without side effects. We have established a comprehensive understanding of the possible herb-drug interactions and identified interaction patterns between the most common herbs and drugs currently in use in the Indian market. For this purpose, we listed common interactors (herbs and allopathic drugs) using available scientific literature. Drugs were then categorized into therapeutic classes and aligned to produce a recognizable pattern present only if interactions were observed between a drug class and herb in the scientific literature. Interestingly, the top three categories (with highest interactors), antibiotics, oral hypoglycemics, and anticonvulsants, displayed synergistic interactions only. Another major interactor category was CYP450 enzymes, a natural component of our metabolism. Both activation and inhibition of CYP450 enzymes were observed. As many allopathic drugs are known CYP substrates, inhibitors or inducers, ingestion of an interacting herb could result in interaction with the co-administered drug. This information is largely unavailable for the Indian population and should be studied in greater detail to avoid such interactions. Although this information is not absolute, the systematic literature review proves the existence of herb-drug interactions in the literature and studies where no interaction was detected are equally important.

Effects of Hibiscus Sabdariffa Calyces Aqueous Extract on the Antihypertensive Potency of Captopril in the Two-Kidney-One-Clip Rat Hypertension Model

Hibiscus sabdariffa aqueous extract (HS) is often used as complementary therapy for hypertension. However, some studies have shown that coadministration with a conventional antihypertensive drug can affect drug potency. We compared the effects of HS plus captopril (CAP) coadministration to HS and CAP administration alone on blood pressure and renin-angiotensin-aldosterone system (RAAS) biomarkers in the rat two-kidney-one-clip (2K1C) model of hypertension. Male Sprague Dawley rats were randomly divided into seven groups (n=6/group), a normal control (SHAM) group, and six 2K1C groups. In 2K1C animals, hypertension was induced using a stainless microclip (inner diameter of 0.20 mm). Four weeks after 2K1C surgery, blood pressure was significantly higher than in the SHAM group. Then, model rats were randomly divided into negative control (2K1C, no treatment), positive control (4.5 mg captopril/200 g body weight [BW] orally [p.o.]), HS alone (30 mg/200 g BW; p.o.), and 3 co-treatment groups receiving HS (15, 30, or 60 mg/200 g BW; p.o.) plus 4.5 mg/200 g BW captopril. The treatments were performed for two weeks. Blood pressure was significantly reduced by all the drug treatments to near the level of SHAM controls. Plasma renin level, serum angiotensin converting enzyme (ACE) activity, and plasma angiotensin II level were also significantly elevated in the 2K1C group compared to the SHAM group. Both serum ACE activity and plasma angiotensin II level were significantly reduced to near SHAM group levels by all the drug treatments. Hibiscus sabdariffa aqueous extract alone can reduce blood pressure. This extract appears could be used as a supplement with captopril but may not provide any additional benefit.

Bush mint (Hyptis suaveolens) and spreading hogweed (Boerhavia diffusa) medicinal plant extracts differentially affect activities of CYP1A2, CYP2D6 and CYP3A4 enzymes

ETHNO-PHARMACOLOGICAL RELEVANCE

Hyptis suaveolens (L) Poit and Boerhavia diffusa Linn are medicinal herbal plants commonly found in the tropics and sub-tropics. They are used to treat various conditions among them boils, dyslipidaemia, eczema, malaria, jaundice and gonorrhoea. Thus, the herbal medicinal extracts are now found as part of some commercial herbal formulations. There has not been adequate characterization of these medicinal herbs on their effects on drug metabolising enzymes.

AIM OF THE STUDY

To investigate the effects of extracts of Hyptis suaveolens (HS) and Boerhavia diffusa (BD) on activity of drug metabolising enzymes, CYP1A2, CYP2D6 and CYP3A4, as well predict their potential for herb-drug interaction. A secondary aim was to identify constituent compounds such as polyphenolics, in the crude extract preparations of Hyptis suaveolens and Boerhavia diffusa and measure them for activity.

MATERIALS AND METHODS

CYP450 inhibition assays using recombinant CYP450 (rCYP) and fluorescence screening employing individual isozymes (CYP1A2, CYP2D6 and CYP3A4) were used to determine reversible- and time-dependent inhibition (TDI) profiles of extracts of Hyptis suaveolens and Boerhavia diffusa. Inhibition kinetic parameters, K_i and K_inact were also estimated. UPLC-MS employing a Synapt G2 (ESI negative) coupled to a PDA detector was used to identify polyphenolic compounds in crude extracts of Hyptis suaveolens and Boerhavia diffusa.

RESULTS

The inhibitory potency of Hyptis suaveolens and Boerhavia diffusa extracts varied among the different enzymes, with CYP1A2 (3.68 ± 0.10µg/mL) being the least inhibited by HS compared to CYP2D6 (1.39 ± 0.01µg/mL) and CYP3A4 (2.36 ± 0.57µg/mL). BD was most potent on CYP3A4 (7.36 ± 0.94µg/mL) compared to both CYP2D6 (17.79 ± 1.02µg/mL) and CYP1A2 (9.48 ± 0.78µg/mL). Extracts of Hyptis suaveolens and Boerhavia diffusa exhibited TDIs on all CYPs. The most prominent phenolic candidates identified in both medicinal herbs using UPLC-MS analysis included caffeic acid, rutin, quercetin, citric acid, ferulic acid and gluconic acid. These phenolic compounds are thought to potentially give HS and BD their therapeutic effects and inhibitory characteristics affecting CYP450 activities. In vivo predictions showed the potential for HS and BD extracts to cause significant interactions if co-administered with other medications.

CONCLUSIONS

The study reveals that crude aqueous extracts of HS and BD potentially inhibit drug metabolising isozymes CYP1A2, CYP2D6 and CYP3A4 in a reversible and time-dependent manner. Thus care should be taken when these extracts are co-administered with drugs that are substrates of CYP1A2, CYP2D6 and CYP3A4.

Effect of Khat (Catha edulis) Use on the Bioavailability, Plasma Levels and Antimalarial Activity of Chloroquine

OBJECTIVES

This study aimed to evaluate the effect of khat (Catha edulis) on chloroquine (CQ) bioavailability in healthy Yemeni adults and its effect on CQ plasma levels and parasite clearance among malaria patients.

METHODS

This study took place between January and April 2007 in Bajil and Sana'a, Yemen. Two CQ doses (600 mg each) were given to 15 healthy males on separate occasions; the first dose was followed by a khat-chewing session (phase one) while controls abstained from khat-chewing for the second (phase two). Additionally, 103 patients with Plasmodium falciparum-induced malaria, including both regular khat chewers (n = 57) and non-khat chewers (n = 46), were treated with CQ (25 mg/kg) over three days. Pharmacokinetic parameters were analysed among both controls and malaria patients. Parasite clearance was also investigated for the latter group.

RESULTS

The mean area under the concentration-time curve (AUC) was 2,108.9 versus 2,797.4 ng/hour/mL, mean peak plasma concentration (Cmax) was 415.6 versus 508.7 ng/mL and mean time to reach Cmax was 3.8 versus 3.6 hours for controls in phase one versus phase two, respectively; both AUC and Cmax levels were significantly reduced by khat-chewing (P <0.050). For khat- versus non-khat-chewing malaria patients, mean plasma CQ concentrations were 266.4 ng/mL versus 427.5 ng/mL (P <0.001). Furthermore, CQ was effective in 71.7% and 75.4% of non-khat and khat-chewing malaria patients, respectively (P = 0.823).

CONCLUSION

Khat-chewing was found to significantly reduce plasma CQ levels among healthy volunteers and malaria patients. While receiving CQ treatment, patients should be advised not to chew khat.

Interactions between herbs and conventional drugs: overview of the clinical data

This article provides an overview of the clinical evidence of interactions between herbal and conventional medicines. Herbs involved in drug interactions--or that have been evaluated in pharmacokinetic trials--are discussed in this review. While many of the interactions reported are of limited clinical significance and many herbal products (e.g. black cohosh, saw palmetto, echinacea, hawthorn and valerian) seem to expose patients to minor risk under conventional pharmacotherapy, a few herbs, notably St. John's wort, may provoke adverse events sufficiently serious to endanger the patients' health. Healthcare professionals should remain vigilant for potential interactions between herbal medicines and prescribed drugs, especially when drugs with a narrow therapeutic index are used.

In vitro vasorelaxation mechanisms of bioactive compounds extracted from Hibiscus sabdariffa on rat thoracic aorta

BACKGROUND

In this study, we suggested characterizing the vasodilator effects and the phytochemical characteristics of a plant with food usage also used in traditional treatment of arterial high blood pressure in Senegal.

METHODS

Vascular effects of crude extract of dried and powdered calyces of Hibiscus sabdariffa were evaluated on isolated thoracic aorta of male Wistar rats on organ chambers. The crude extract was also enriched by liquid-liquid extraction. The various cyclohexane, dichloromethane, ethyl acetate, butanol extracts obtained as well as the residual marc were subjected to Sephadex LH-20 column chromatography. The different methanolic eluate fractions were then analyzed by Thin Layer (TLC) and High Performance Liquid Chromatography (HPLC) and their vascular effects also evaluated.

RESULTS

The H. Sabdariffa crude extract induced mainly endothelium-dependent relaxant effects. The endothelium-dependent relaxations result from NOS activation and those who not dependent to endothelium from activation of smooth muscle potassium channels. The phytochemical analysis revealed the presence of phenolic acids in the ethyl acetate extract and anthocyans in the butanolic extract. The biological efficiency of the various studied extracts, in term of vasorelaxant capacity, showed that: Butanol extract > Crude extract > Residual marc > Ethyl acetate extract. These results suggest that the strong activity of the butanolic extract is essentially due to the presence of anthocyans found in its fractions 43-67.

CONCLUSION

These results demonstrate the vasodilator potential of hibiscus sabdariffa and contribute to his valuation as therapeutic alternative.

The potential inhibitory effect of antiparasitic drugs and natural products on P-glycoprotein mediated efflux

The potential inhibitory effect on P-glycoprotein (Pgp) by antiparasitic drugs and natural compounds was investigated. Compounds were screened for Pgp interaction based on inhibition of Pgp mediated [3H]-taxol transport in Caco-2 cells. Bidirectional transport of selected inhibitors was further evaluated to identify potential Pgp substrates using the Caco-2 cells. Of 21 antiparasitics tested, 14 were found to inhibit Pgp mediated [3H]-taxol with K(iapp) values in the range 4-2000 microM. The antimalarial quinine was the most potent inhibitor with a K(iapp) of 4 microM. Of the 12 natural compounds tested, 3 inhibited [3H]-taxol transport with K(iapp) values in the range 50-400 microM. Quinine, amodiaquine, chloroquine, flavone, genistein, praziquantel, quercetin and thiabendazole were further investigated in bidirectional transport assays to determine whether they were substrates for Pgp. Transport of quinine in the secretory direction exceeded that in the absorptive direction and was saturable, suggesting quinine being a Pgp substrate. The rest of the compounds inhibiting Pgp showed no evidence of being Pgp substrates. In conclusion, we have demonstrated that a substantial number of antiparasitic and natural compounds, in a range of concentrations, are capable of inhibiting Pgp mediated [3H]-taxol efflux in Caco-2 cells, without being substrates and this may have implications for drug interactions with Pgp.

Self-medication practices in Khartoum State, Sudan

OBJECTIVE

The aim of this study was to estimate the prevalence of self-medication with proprietary medicines and herbs in Khartoum State, Sudan, and to evaluate factors associated with self-medication.

METHODS

A pre-piloted questionnaire was used to collect data from a sample of 1,200 individuals, selected from all three cities of Khartoum State using a multistage stratified clustered sampling.

RESULTS

The response rate was 83.3%. Medicines, including herbs, were used by 81.8% of the respondents without a medical consultation within 2 months prior to the study period. Proprietary medicines alone were used by 28.3% (CI: 25.6-31.2), herbs alone by 20.7% (CI: 18.3-23.4), while 32.8% (CI: 29.9-35.8) had used both. Self-medication with proprietary medicines was least common with the middle-aged (OR: 0.12; 0.09-0.17), the elderly (OR: 0.29; 0.20-0.42) and low level of education [illiterate (OR: 0.26, 0.18-0.37) and primary/intermediate school (OR: 0.07, 0.04-0.11)]. It was most associated with low (OR: 5.3; 3.8-7.4) and middle income (OR: 4.3; 3.1-5.9), but no gender difference was found (P>0.05). Self-medication behaviour with herbs was most associated with middle-age (OR: 1.7; 1.3-2.2), female gender (OR: 2.2 (1.7-2.8) and lowest income earners (OR: 2.5; 1.9-3.5).

CONCLUSIONS

The prevalence of self-medication with medicines including herbs in urban areas of Khartoum State is high. Self-medication behaviour varies significantly with a number of socio-economic characteristics. Our findings have major public health policy implications for countries like Sudan.

Effects of water extract ofHibiscus sabdariffa, Linn (Malvaceae) ‘Roselle’ on excretion of a diclofenac formulation

The effect of beverages prepared from the dried calyx of the flowers of Hibiscus sabdariffa on the excretion of diclofenac was investigated using a controlled study in healthy human volunteers. A high pressure liquid chromatographic method was used to analyse the 8 h urine samples collected after the administration of diclofenac with 300 mL (equivalent to 8.18 mg anthocyanins) of the beverage administered daily for 3 days. An unpaired two-tailed t-test was used to analyse for significant difference observed in the amount of diclofenac excreted before and after administration of the beverage. There was a reduction in the amount of diclofenac excreted and the wide variability observed in the control with the water beverage of Hibiscus sabdariffa (p < 0.05). There is an increasing need to counsel patients against the use of plant beverages with drugs.

Protection from anthrax toxin-mediated killing of macrophages by the combined effects of furin inhibitors and chloroquine

Cell surface proteolytic processing of anthrax protective antigen by furin or other furin-related proteases is required for its oligomerization, endocytosis, and function as a translocon for anthrax lethal and edema factors. Countering toxin lethality is essential to developing effective chemotherapies for anthrax infections that have proceeded beyond the stage at which antibiotics are effective. The primary target for toxin is the macrophage, which can be killed by lethal factor via both necrotic and apoptotic pathways. Here we show that three high-affinity inhibitors of furin efficiently blocked killing of murine J774A.1 macrophages by recombinant protective antigen plus lethal factor: RRD-eglin and RRDG-eglin, developed by engineering the protein protease inhibitor eglin c, and the peptide boronic acid inhibitor acetyl-Arg-Glu-Lys-boroArg pinanediol. Inhibition of killing was dose dependent and correlated with prevention of protective antigen processing. Previous studies have shown that weak bases, such as chloroquine, which neutralize acidic compartments, also interfere with toxin-dependent killing. Here we show that combining furin inhibitors and chloroquine strongly augments the inhibition of toxin-dependent killing, suggesting that combined use of antifurin drugs and chloroquine might provide enhanced therapeutic benefits. Reversible furin inhibitors protected against anthrax toxin killing for at least 5 h, but by 8 h, toxin-dependent killing resumed even though furin inhibitors were still active. An irreversible chloromethylketone inhibitor did not exhibit this loss of protection.

Biowaiver monographs for immediate release solid oral dosage forms based on biopharmaceutics classification system (BCS) literature data: chloroquine phosphate, chloroquine sulfate, and chloroquine hydrochloride

Literature data on the properties of chloroquine phosphate, chloroquine sulfate, and chloroquine hydrochloride related to the Biopharmaceutics Classification System (BCS) are reviewed. The available information indicates that these chloroquine salts can be classified as highly soluble and highly permeable, i.e., BCS class I. The qualitative composition of immediate release (IR) tablets containing these Active Pharmaceutical Ingredients (APIs) with a Marketing Authorization (MA) in Belgium (BE), Germany (DE), Finland (FI), and The Netherlands (NL) is provided. In view of these MA's and the critical therapeutic indication of chloroquine, it is assumed that the registration authorities had evidence that these formulations are bioequivalent to the innovator. It is concluded that IR tablets formulated with these excipients are candidates for a biowaiver.

Phytochemical, pharmacological and toxicological aspects ofHibiscus sabdariffa L.: a review

This article reviews the reported phytochemical, pharmacological and toxicological properties of Hibiscus sabdariffa L. (English: roselle, red sorrel; Arabic: karkade), the calyces of which are used in many parts of the world to make cold and hot drinks. Nutritionally, these contain ascorbic acid (vitamin C). In folk medicine, the calyx extracts are used for the treatment of several complaints, including high blood pressure, liver diseases and fever. The pharmacological actions of the calyx extracts include strong in vitro and in vivo antioxidant activity. In rats and rabbits, the extract showed antihypercholesterolaemic, antinociceptive and antipyretic, but not antiinflammatory activities. In rat and man a strong antihypertensive action has been demonstrated. The effects of the calyx extracts on smooth muscles in vitro are variable, but they mostly inhibit the tone of the isolated muscles. In healthy men, consumption of H. sabdariffa has resulted in significant decreases in the urinary concentrations of creatinine, uric acid, citrate, tartrate, calcium, sodium, potassium and phosphate, but not oxalate. Oil extracted from the plant's seeds has been shown to have an inhibitory effect on some bacteria and fungi in vitro. The plant extracts are characterized by a very low degree of toxicity. The LD50 of H. sabdariffa calyx extract in rats was found to be above 5000 mg/kg. A single report has suggested that excessive doses for relatively long periods could have a deleterious effect on the testes of rats. In view of its reported nutritional and pharmacological properties and relative safety, H. sabdariffa and compounds isolated from it (for example, anthocyanins and Hibiscus protocatechuic acid) could be a source of therapeutically useful products.

Effect of grapefruit juice on plasma chloroquine kinetics in mice

1. It is known that grapefruit juice (GFJ) may interact with drugs concomitantly administered by inhibiting first-pass metabolism during the intestinal absorption phase. However, its interaction with chloroquine has not been studied previously. 2. Grapefruit juice (4 mL/kg) was given orally to mice 1 h prior to oral administration of chloroquine (100 mg/kg) and the concentration of the latter drug was measured fluorometrically in the plasma 0, 0.5, 0.75, 1, 2, 3, 4, 6, 8, 12, 18 and 24 h after its administration. 3. The mean (+/-SEM) of area under the curve values after administration of water +/- control) and GFJ were 5.34 +/- 0.38 and 7.01 +/- 0.66 mg.h/L, respectively. The corresponding mean C(max) values were 763.4 +/- 39.1 and 859.2 +/- 45.2 mg/L and the corresponding T(max) values (median) were 2.65 and 2.95 h. 4. The results suggest that GFJ coingestion increased the plasma concentration of chloroquine and altered some kinetic parameters of chloroquine. The clinical significance of this interaction in patients with malaria needs to be investigated.

Resistance of Plamodium falciparum to antimalarial drugs in Zaragoza (Antioquia, Colombia), 1998

Plasmodium falciparum sensitivity to chloroquine (CHL), amodiaquine (AMO) and sulfadoxine/pyrimethamine (SDX/PYR) was assessed in vivo and in vitro in a representative sample from the population of Zaragoza in El Bajo Cauca region (Antioquia-Colombia). There were 94 patients with P. falciparum evaluated. For the in vivo test the patients were followed by clinical examination and microscopy, during 7 days. The in vitro test was performed following the recommendations of the World Health Organization. The in vivo prevalence of resistance to CHL was 67%, to AMO 3% and to SDX/PYR 9%. The in vitro test showed sensitivity to all antimalarials evaluated. Concordance for CHL between the in vivo and in vitro tests was 33%. For AMO and SDX/PYR, the concordance was 100%. We conclude that a high percentage of patients are resistant to CHL (in vivo). A high rate of intestinal parasitism might explain in part, the differences observed between the in vivo and the in vitro results. Therefore, new policies and treatment regimens should be proposed for the treatment of the infection in the region. Nationwide studies assessing the degree of resistance are needed.

Knowledge and misconceptions about malaria among secondary school students and teachers in Kassala, eastern Sudan

This study reports the responses of high secondary school students and teachers to a questionnaire on their knowledge and misconceptions about malaria. Knowledge about symptoms and cause of malaria seems to be adequate. However, there were deficiencies regarding knowledge of the seriousness of malaria in primigravidas and children. There was an exaggerated belief that chloroquine may cause abortion. There were also important misconceptions regarding the causation of malaria by the plant Unkoleeb (sorghum saccharatum), the belief that the local beverage Aradaib (Tramindus indica) cures malaria, as well as beliefs that chloroquine injections are more effective than tablets, that intravenous fluids are essential for treatment of every attack, and that multi-vitamins may prevent the disease. The study throws light on areas where health education should be focused.

Clinical pharmacokinetics and metabolism of chloroquine. Focus on recent advancements

This paper presents the current state of knowledge on chloroquine disposition, with special emphasis on stereoselectivity and microsomal metabolism. In addition, the impact of the patient's physiopathological status and ethnic origin on chloroquine pharmacokinetics is discussed. In humans, chloroquine concentrations decline multiexponentially. The drug is extensively distributed, with a volume of distribution of 200 to 800 L/kg when calculated from plasma concentrations and 200 L/kg when estimated from whole blood data (concentrations being 5 to 10 times higher). Chloroquine is 60% bound to plasma proteins and equally cleared by the kidney and liver. Following administration chloroquine is rapidly dealkylated via cytochrome P450 enzymes (CYP) into the pharmacologically active desethylchloroquine and bisdesethylchloroquine. Desethylchloroquine and bisdesethylchloroquine concentrations reach 40 and 10% of chloroquine concentrations, respectively; both chloroquine and desethylchloroquine concentrations decline slowly, with elimination half-lives of 20 to 60 days. Both parent drug and metabolite can be detected in urine months after a single dose. In vitro and in vivo, chloroquine and desethylchloroquine competitively inhibit CYP2D1/6-mediated reactions. Limited in vitro studies and preliminary data from clinical experiments and observations point to CYP3A and CYP2D6 as the 2 major isoforms affected by or involved in chloroquine metabolism. In vitro efficacy studies did not detect any difference in potency between chloroquine enantiomers but, in vivo in rats, S(+)-chloroquine had a lower dose that elicited 50% of the maximal effect (ED950) than that of R(-)-chloroquine. Stereoselectivity in chloroquine body disposition could be responsible for this discrepancy. Chloroquine binding to plasma proteins is stereoselective, favouring S(+)-chloroquine (67% vs 35% for the R-enantiomer). Hence, unbound plasma concentrations are higher for R(-)-chloroquine. Following separate administration of the individual enantiomers, R(-)-chloroquine reached higher and more sustained blood concentrations. The shorter half-life of S(+)-chloroquine appears secondary to its faster clearance. Blood concentrations of the S(+)-forms of desethylchloroquine always exceeded those of the R(-)-forms, pointing to a preferential metabolism of S(+)-chloroquine.