Clinical trials of amodiaquine in onchocerciasis

Twenty onchocerciasis patients from the rain-forest zone of Western Nigeria were treated with amodiaquine in total dosages ranging from 22 to 68 mg/kg of body weight given over 2-9 days. There was no activity against either the microfilariae or adult forms of Onchocerca volvulus. It is concluded that the drug, which was poorly tolerated by 12 patients, is ineffective against human onchocerciasis.     

Chemotherapeutic studies on Litomosoides carinii infection of Mastomys natalensis. 3. The activity of drugs against adult parasites

Comparative studies of the chemotherapeutic activity of various filaricides were carried out and the results in Litomosoides carinii infections of Mastomys natalensis were analysed with special reference to macrofilaricidal activity. The administration of suramin in daily subcutaneous doses of 40 mg per kg of body weight for 5 consecutive days showed marked activity against macrofilariae and killed the adult worms within 6 weeks after the beginning of treatment. The microfilarial count of the circulating blood declined steadily to nearly 0 in more than 2 months after microfilarial production by female worms in the pleural cavities had ceased. Amodiaquine proved to be markedly effective against adult parasites, whereas stibophen, tartar emetic, and the free acid of stibocaptate gave inadequate results.     

Studies with the schistosomicide oxamniquine (UK-4271). I. Activity in rodents and in vitro

A single oral or intramuscular dose of oxamniquine (6-hydroxymethyl-2-isopropylaminomethyl-7-nitro-1,2,3,4-tetrahydroquinoline) had potent schistosomicidal action against Schistosoma mansoni in mice and hamsters. No convincing activity was demonstrated against Chinese S. japonicum in either host, or against Nigerian S. haematobium in hamsters, although the schistosomicide hycanthone also was inactive orally against the latter.Male S. mansoni were markedly more susceptible than females in vivo but not in vitro. Against a Puerto Rican strain in mice the oral ED₅₀ and ED₉₉ values were 20 and 44 mg./kg. respectively given as a single dose, and 28·5 and 57·5 mg./kg. respectively given as 5 consecutive daily doses of 5·7 and 11·5 mg./kg.; by the intramuscular route ED₅₀ and ED₉₉ values were 18 and 42 mg./kg. respectively as single doses, and 19·5 and 37 mg./kg. respectively given as 5 consecutive daily injections of 3·9 and 7·4 mg./kg. There were strain differences in reaction to the drug. When administered orally against an East African strain in mice, oxamniquine was 2–3 times more potent than hycanthone, 5–11 times more potent than niridazole and 8–11 times more potent than lucanthone. Oral potency against Puerto Rican S. mansoni in hamsters was similar to that in mice, but intramuscular activity was considerably greater, the single dose ED₅₀ and ED₉₉ being only 6·7 and 12 mg./kg. respectively.The acute LD₅₀ in mice was 1,300 mg./kg. (oral) or more than 2,000 mg./kg. (intramuscular), and by multiple dose regimens toxic symptoms were produced only by doses greatly in excess of the curative levels. Observations in other species and safety tests in man confirmed the suitability of the compound for clinical trial.     

Efficacy of co-administered diethylcarbamazine and albendazole against adult Wuchereria bancrofti

Although diethylcarbamazine (DEC) and albendazole are recommended to interrupt transmission of Wuchereria bancrofti, little is known about the macrofilaricidal effect of this drug combination. Forty-seven men with W. bancrofti infection were randomly assigned to receive a single dose of either DEC alone (6 mg/kg) (n=25) or a combination of DEC (6 mg/kg) and albendazole (400 mg) (n=22). Physical examinations for scrotal nodules (resulting from worm death) and ultrasound examinations (to detect living adult worms) were performed before treatment and 7, 14, 30, 45, 60, 90, 180, 270 and 360 days after treatment. Blood was examined for microfilariae before and 30 days and 360 days after treatment. Seven days post treatment, intrascrotal nodules were detected at the site of 21 (46.7%) adult worm nests in men who received DEC alone compared with 2 (6.1%) sites in men who received DEC and albendazole (P=0.002). One year after treatment, 10 (22.2%) original adult worm nests remained detectable by ultrasound among men who received DEC alone compared with 18/32 (56.3%) nests among men who received both drugs (P=0.016). Microfilaraemia prevalence and density decreased to a similar extent in both groups. Addition of albendazole appeared to decrease the macrofilaricidal effect of DEC against W. bancrofti, with no detectable enhancement in microfilarial suppression.     

Studies on the experimental chemotherapy of Angiostrongylus malaysiensis infection in rats with mebendazole and levamisole

The effect of levamisole hydrochloride and mebendazole on Angiostrongylus malaysiensis infection in albino rats was studied. Animals at different stages of infection were treated with various oral doses of levamisole and mebendazole with the aim of finding an effective treatment regime. Levamisole was most effective for treating rats seven days after infection but its efficacy dropped as infection progressed. Mebendazole given at a dose of 1 mg/kg for five days was more effective against early larval stages (97 · 39% efficacy). At 5 mg/kg for five days mebendazole was more effective than levamisole against all stages of the infection.     

Assessment of the neurotoxicity of oral dihydroartemisinin in mice

High doses of the oil-soluble antimalarial artemisinin derivatives artemether and arteether, given by intramuscular injection to experimental mammals, produce an unusual pattern of selective damage to brainstem centres predominantly involved in auditory processing and vestibular reflexes. We have shown recently, in adult Swiss albino mice, that constant exposure either from depot intramuscular injection of oil-based artemisinin derivatives, or constant oral intake carries relatively greater neurotoxic potential than other methods of drug administration. Using the same model, oral dihydroartemisinin suspended in water was administered once or twice daily at different doses ranging from 50 to 300 mg/kg/day for 28 days. The neurotoxic potential of the oral dihydroartemisinin was assessed and compared to that of oral artemether and artesunate. Oral artemether, artesunate, and dihydroartemisinin had similar neurotoxic effects with no significant clinical or neuropathological evidence of toxicity at doses below 200 mg/kg/day. These data indicate that once and twice daily oral administration of artemether, artesunate and dihydroartemisinin is relatively safe when compared to intramuscular administration of the oil-based compounds.     

High-dose sodium stibogluconate treatment of cutaneous leishmaniasis in Kenya

Cutaneous leishmaniasis caused by Leishmania aethiopica usually responds poorly to conventional doses of pentavalent antimonial drugs. We treated three patients with cutaneous leishmaniasis acquired in Kenya, presumed or documented to be caused by L. aethiopica, with intravenous sodium stibogluconate, 18 to 20 mg Sb/kg body-weight twice daily for 30 days. All patients had a good response to treatment, with disappearance of parasites from skin smears and cultures after 14 to 27 days, clinical healing of the lesions, and no recurrence during a three to 18-month follow-up. Side effects of treatment were minor. We conclude that this high dose sodium stibogluconate regimen is safe and effective for treating cutaneous leishmaniasis caused by L. aethiopica in Kenya.     

Litomosoides carinii infection in cotton-rats: evolution of microfilaraemia before and after treatment with diethylcarbamazine and suramin

The activity of diethylcarbamazine (DEC) and suramin (S) on Litomosoides carinii filariasis was assessed by the study of microfilaraemia in 30 cotton-rats (Sigmodon hispidus). DEC (per os) and S (injected subcutaneously) were administered alone or in combination, at doses of 50 mg/kg/day for five consecutive days. 15 rats were treated at day 91 after infection and 15 others at day 184. The immediate but temporary efficacy observed with DEC was in contrast to the delayed and long-lasting effect of S. With combined therapy there was neither antagonism nor synergism. The demonstration of an apparently smaller reduction of parasitaemia in the rats treated with DEC before the plateau phase of the microfilaraemia was consistent with the lack of action of this drug on microfilariae outside the blood system.     

Methadone, pentobarbital, pimozide and ethanol-intake

For 28 days, water-deprived rats were given a daily, 1-hr opportunity to take a sweetened ethanol solution (ES) or water. Across days under this regimen, rats gained weight normally and increased intake of ES until they were taking considerable amounts. Across the next 13 days of the regimen, selected groups were given, before the opportunity to drink, one of five doses of methadone (from 0.5 to 8.0 mg/kg), pentobarbital (from 5 to 30 mg/kg), or their vehicles. Large doses of both agents increased intakes, with methadone (1 and 2 mg/kg) increasing only ES-intake. Subsequently, while the daily regimen continued, rats were given pimozide (0.2, 0.4, or 0.6 mg/kg) at either 1 or 4 hr before the opportunity to drink. Pimozide did not reduce ES-intake. Next, they were given a dose of pentobarbital (5.0 mg/kg) with challenge doses of naloxone (0.3, 1.0, 3.0 mg/kg). Naloxone dose-relatedly antagonized pentobarbital's potential to increase intakes.     

Evaluation of STS-557 as an oral contraceptive in male rat

To examine the nature and site of post-testicular antifertility action of STS-557 (17 alpha-cyanomethyl-17 beta-hydroxy-estra-4,9-dien-3-one), male rats were given the steroid orally daily for 60 days. In doses of 1 and 5 mg per animal per day it had no effect on fertility at the end of 3 weeks of treatment. When the treatment was extended for 60 days, spermatogenic arrest and loss of libido were evident in animals treated with 5 mg dose; animals receiving 1 mg dose of steroid showed no decrease of spermatogenesis or sexual activity and their fertility remained unaffected. In 35-day-old growing rats the steroid produced inconsistent effects on spermatogenesis after a 15-day treatment period at 1 and 5 mg doses. Both in adult and in growing rats the steroid caused a significant reduction in the weights and secretory function of the epididymis and other accessory sex organs; a dose-dependent response was seen in all the sex organs. Evaluation in castrated rat model revealed that STS-557 is a weak anti-androgen. Although this steroid is a potent inhibitor of spermatogenesis, its inhibitory effect on Leydig cell function is a contraindication for its use as a male oral contraceptive.     

Chemotherapeutic studies on Litomosoides carinii infection of Mastomys natalensis. 1. The filaricidal action of 2,6-bis-benzimidazoles

The antifilarial action of 2-[2-(4-hydroxyphenyl)-6-benzimidazolyl]-6-(1-methyl-4-piperazyl) benzimidazole (HOE 33258) was investigated in Mastomys natalensis infected with Litomosoides carinii. The subcutaneous administration of HOE 33258 in a single daily dose for 5 consecutive days, or at other intervals, produced, depending on the dosage, a rapid reduction in the number of microfilariae in the circulating blood. The reduction amounted to more than 90% within 7-14 days after the treatment was started or at the end of the dosage schedule. The small, slow increase in the microfilarial count during a period of 6-7 weeks after treatment ended reached not more than half the number present before treatment. HOE 33258 showed marked activity on the reproductive system of mature female worms, although only few macrofilariae were killed by the drug. The results also demonstrated the usefulness of L. carinii infection of M. natalensis as a model for the evaluation of the filaricidal activity of drugs.     

Survival of Loa loa following transplantation from drills (Mandrillus leucophaeus) into jirds (Meriones unguiculatus): parasitology and pathology

Two drills infected with Loa loa maintained a microfilaraemia for four and a half years ranging from less than 1 mf/100 μl to 1150 mf/100 μl. No significant tissue reactions to the adult worms were seen at autopsy. Adult worms were transplanted into the peritoneal cavities of naive jirds when a persistent microfilaraemia first developed by 17 days. Retransplantation of adult worms into naive jirds produced a microfilaraemia and microfilariae in the peritoneal cavities of three out of five animals. These three animals were all negative for circulating parasites by eight and a half months. The tissue reactions to the worms in the jirds are described, including a granulomatous response surrounding adults and a myositis involving microfilariae.     

Iron,Oxidative Stress and Gestational Diabetes

Both iron deficiency and hyperglycemia are highly prevalent globally for pregnant women. Iron supplementation is recommended during pregnancy to control iron deficiency. The purposes of the review are to assess the oxidative effects of iron supplementation and the potential relationship between iron nutrition and gestational diabetes. High doses of iron (~relative to 60 mg or more daily for adult humans) can induce lipid peroxidation in vitro and in animal studies. Pharmaceutical doses of iron supplements (e.g., 10× RDA or more for oral supplements or direct iron supplementation via injection or addition to the cell culture medium) for a short or long duration will induce DNA damage. Higher heme-iron intake or iron status measured by various biomarkers, especially serum ferritin, might contribute to greater risk of gestational diabetes, which may be mediated by iron oxidative stress though lipid oxidation and/or DNA damage. However, information is lacking about the effect of low dose iron supplementation (≤60 mg daily) on lipid peroxidation, DNA damage and gestational diabetes. Randomized trials of low-dose iron supplementation (≤60 mg daily) for pregnant women are warranted to test the relationship between iron oxidative stress and insulin resistance/gestational diabetes, especially for iron-replete women.     

Infection of Aedes aegypti with Brugia pahangi administered by enema: results of quantitative infection and loss of infective larvae during blood feeding

A technique for infecting mosquitoes with known numbers of Brugia pahangi microfilariae by enema is described. Virtually all mosquitoes receiving three microfilariae or more by this route contained infective larvae 10 days later. Within a range of 1 to 40 microfilariae, numbers of infective larvae recovered (Y) were related to the numbers of microfilariae administered (X) by the equation log₁₀Y = 0.04 + 0.84log₁₀X. Mosquitoes feeding on sugar for up to 20 days did not lose a significant number of infective larvae. A blood meal 10 days after infection reduced the proportion of females still infected, as well as the number of worms remaining in those still infected. A second blood meal on day 17 after infection only reduced the proportion of mosquitoes still infected. Adults reared on a low larval diet were less susceptible to infection, and a refractory mosquito strain did not support the development of third-stage larvae. Filarial worms had no effect on mosquito mortality until more than 30 microfilariae were administered.     

Comparative study of the effects of artemether and artesunate on juvenile and adult Schistosoma mansoni in experimentally infected mice

Artemether and artesunate, derivatives of the antimalarial artemisinin, also exhibit antischistosomal properties. There is a need to assess comparatively the activity of both compounds against different developmental stages of schistosome parasites. Since artemisinin derivatives will be increasingly used to treat malaria, it is important to study the effects of 7-day monotherapy regimens on schistosome infections. We carried out experiments with mice, infected with juvenile or adult Schistosoma mansoni, and treated with artemether or artesunate at various doses and regimens including those currently used for monotherapy of malaria. Three doses of artemether, at concentrations of 150 or 300 mg/kg, administered to mice with juvenile S. mansoni resulted in worm reductions of 88-97%, which were significantly higher than the 67-77% obtained with artesunate (P < 0.05). Total concentrations of 600 or 800 mg/kg artemether, administered over 2 or 4 consecutive days to mice with adult S. mansoni, reduced the worm burden significantly by 46-51% (P < 0.05). The reduction of the worm burden observed with artesunate was considerably lower, 24-33%, and not significant when compared with untreated control mice. Seven-day monotherapy regimens of artemether or artesunate given at different concentrations to mice with adult S. mansoni showed total worm reductions of 53-61% or 34-49%, respectively. We conclude that artemether and artesunate are efficacious antischistosomal agents, with artemether displaying consistently higher activities. Our findings may contribute to the current strategic discussions on the effect and use of artemisinin derivatives against schistosomes when they are used in malaria chemotherapy in areas of co-endemicity of both parasites.     

Single dose vaccination with AS03-adjuvanted H5N1 vaccines in a randomized trial induces strong and broad immune responsiveness to booster vaccination in adults

Priming a population with a pre-pandemic vaccine is being considered to maximize the response upon subsequent vaccination with a true pandemic vaccine more closely matched to the causative pandemic strain. The present study explored this prime-boost concept by evaluating different primary schedules with the pre-pandemic A/Vietnam/1194/2004(NIBRG-14) vaccine, containing 3.75 μg of HA, followed by a 6-month booster with a vaccine formulated with 3.75 μg HA of either the same strain or with A/Indonesia/05/2005(IBCDC-RG2), a heterologous strain from a different clade. In this multicentre, open, randomized study (NCT00430521) we measured immune responses in four groups (N = 48–60) of adults aged 18–60 years who received a single booster administration of either A/Indonesia/05/2005 or A/Vietnam/1194/2004 vaccine 6 months after a 1- or 2-dose (given 21 days apart) primary vaccination with A/Vietnam/1194/2004. All prime-boost schedules assessed induced early (7 days post-booster) humoral responses that met regulatory acceptance criteria. Two doses of A/Vietnam/1194/2004 given 6 months apart achieved equivalent homologous seroprotection after the second vaccination (89.6%), when compared to two doses given 21 days apart (92.7–93.2%). Remarkably, two doses of A/Vietnam/1194/2004 given 6 months apart induced a higher cross-reactive seroprotection against A/Indonesia/05/2005 (83.3%) when compared to two doses given 21 days apart (41.5–54.5%). A 6-month A/Indonesia/05/2005 booster dose after one primary dose of A/Vietnam/1194/2004 vaccine induced 92.5% seroprotection against A/Indonesia/05/2005 and 98.1% against A/Vietnam/1194/2004. Since a single booster 6 months after one primary dose of AS03-adjuvanted vaccine induces strong and rapid seroprotective immune response against both homologous and heterologous H5N1 strains, these results might have important implications for public health strategy aiming to organize vaccination campaigns with pre-pandemic vaccines.     

Visceral leishmaniasis unresponsive to antimonial drugs. III. Successful treatment using a combination of sodium stibogluconate plus allopurinol

Five patients with long-standing visceral leishmaniasis who were unresponsive to sodium stibogluconate, 20 mg antimony/kg body-weight once or twice daily, were treated for 14 to 54 days with a combination of sodium stibogluconate at the same dose plus allopurinol at a dose of 20 mg/kg body-weight per day in three divided doses. This combination was safe and effective. Negative splenic aspirate smears were obtained from all patients within 19 days, and none has relapsed in at least 12 months of follow-up.     

Pharmacology and toxicology of an oral tablet whole cells inactivated cholera vaccine in Sprague Dawley rats

Here we further investigate the pharmacological and toxicological properties of a cholera vaccine based on inactivated whole cells presented in either enteric coated (COA) or uncoated (U/C) tablet formulation from Vibrio cholerae C7258 strain. Tablets were dispersed in 2 mL drinking water and administered orally to Sprague Dawley rats distributed in five groups (I COA7, II U/C7 immunized at 0, 7, 69 days and III COA14, IV U/C14 immunized at 0, 14, 69 days and V control group). Serum vibriocidal antibody response was measured after the administration of two doses with an interval of 7-14 days. To further investigate the toxicological aspects a third dose was applied 10 weeks after the initial one. Animals were observed daily and water and food consumption was measured every other day. Periodic blood extractions were performed for hematology, biochemistry, and the titer of serum vibriocidal antibodies was determined. Anatomopathological analysis was performed at days 3 or 14 after the third dose. Results from clinical observations, as well as from water and food consumption and body weigh indicated no toxicity of the vaccine product. Meanwhile, no biological differences were found among different groups in hematological, hemo-chemistry, and anatomopathological studies. Moreover, enteric coated and uncoated tablets against human cholera were found to induce an immune response in rats.     

Single-dose treatment of falciparum malaria with mefloquine: field studies with different doses in semi-immune adults and children in Burma

Different doses of mefloquine (20 and 30 mg/kg of body weight in children, and 750 and 1000 mg in adults) were tested in controlled clinical trials in 89 children and 60 adults who were semi-immune carriers of Plasmodium falciparum. There was no significant difference in the efficacy of the two doses, either in the children or in the adults. An RI-type resistance was found in 1 adult, when recrudescence occurred on day 7, and in 4 children, who showed recrudescence on day 14. In all 5 patients, spontaneous disappearance of parasites was observed at further parasitological checks, thus indicating that mefloquine has a prolonged action. One patient who vomited after taking the drug was successfully retreated with mefloquine on day 14.     

Study of live typhoid vaccine in chimpanzees

Streptomycin-dependent Salmonella typhi containing O and H antigens was administered as a live oral antityphoid vaccine to chimpanzees. Five animals served as controls; 5 others received the vaccine 4 times at 3-day intervals; 4 further animals were given 4 doses of vaccine at 3-day intervals together with streptomycin; and 1 animal received the 4 doses of vaccine and a daily dose of streptomycin. The individual vaccine doses varied between 36×10⁹ and 82×10⁹ organisms, totalling about 258×10⁹ Salm. typhi per animal. The chimpanzees were challenged with 26×10⁹ cells of the virulent Salm. typhi Ty2 strain 10 days after immunization and followed up bacteriologically, serologically and clinically. It was observed that after this very heavy challenge the immunized animals that had received streptomycin with the vaccine were protected to some degree against the infection and showed fewer symptoms. The animal that received vaccine and streptomycin daily did not develop the disease.