Anthelmintic efficacy of trichlorfon and blood parameters of young lambs infected with Haemonchus contortus.

In this study we evaluated the efficacy of trichlorfon against Haemonchus contortus, monitoring its influence on blood parameters and plasma enzymes of lambs with haemonchosis. A lamb group was orally treated with trichlorfon at 100 mg kg-1 while the other group was untreated. Split-plot design analysis was performed with the lamb groups defined as plots while the subplots were the four periods (weeks) of collection. The trichlorfon treatment promoted a significant and effective reduction of fecal egg counts after one week, with efficacies > 99%. After 21 days of treatment, detected blood parameters and serum levels of plasma enzymes were normal. Additionally, serum albumin and urea concentrations increased to normal values, which were not observed in untreated lambs. The treatment with this organophosphate, using a correct oral administration, may represent an effective therapeutic alternative for sheep infected with multi resistant strain of H. contortus.

Effects of Hydrogen Peroxide and Metrifonate on Monogenean ligictaluridus floridanus on Catfish ( Ictalurus punctatus , Rafinesque) Gills.

Hydrogen peroxide (H2O2) and metrifonate (Mtf) are common products used in ectoparasite infestations on fish cultures. The therapeutic efficacy of H2O2 and Mtf on a common monogenean parasite, Ligictaluridus floridanus, was evaluated in channel catfish ( Ictalurus punctatus ). In vitro trials were conducted using excised fish gills naturally infected with L. floridanus, which were immersed in H2O2 (150, 300, and 570 mg L(-1)) and Mtf (0.25, 0.5, and 0.75 mg L(-1)) solutions. The efficacy of the treatments was based on the survival time of the parasites, observed microscopically. In addition, an in vivo trial using catfish juveniles, naturally infected with L. floridanus, was also performed. One group received immersion baths of 570 mg L(-1) H2O2 (3%) during 4 min; the Mtf (90%) group received 0.5 mg L(-1) Mtf for 10 min. Treatments were done on days 3, 7, and 11 of the experiment. Results indicate that baths with Mtf do not significantly reduce the mean intensity of the parasite per gill arch, nor do they reduce the in vitro survival time of parasites during treatment; H2O2 baths at 570 mg L(-1) during 4 min were effective (P < 0.05) against adult and juvenile stages of L. floridanus. This study supports the use of H2O2 as an effective antiparasitic agent against I. punctatus .

Drugs for treating urinary schistosomiasis.

BACKGROUND: Urinary schistosomiasis is caused by an intravascular infection with parasitic Schistosoma haematobium worms. The adult worms typically migrate to the venous plexus of the human bladder and excrete eggs which the infected person passes in their urine. Chronic infection can cause substantial morbidity and long-term complications as the eggs become trapped in human tissues causing inflammation and fibrosis. We summarised evidence of drugs active against the infection. This is new edition of a review first published in 1997. OBJECTIVES: To evaluate the efficacy and safety of drugs for treating urinary schistosomiasis. SEARCH METHODS: We searched the Cochrane Infectious Diseases Group Specialized Register, MEDLINE, CENTRAL, EMBASE and LILACS and reference lists of articles up to 23 May 2014. SELECTION CRITERIA: Randomized controlled trials (RCTs) of antischistosomal drugs and drug combinations compared to placebo, no intervention, or each other. DATA COLLECTION AND ANALYSIS: Two researchers independently screened the records, extracted the data and assessed risk of bias. The primary efficacy outcomes were parasitological failure (defined as the continued presence of S. haematobium eggs in the urine at time points greater than one month after treatment), and percent reduction of egg counts from baseline. We presented dichotomous data as risk ratios (RR), and continuous data as mean difference (MD), alongside their 95% confidence intervals (CIs). Where appropriate we combined trials in meta analyses or tables. We assessed the quality of evidence using the GRADE approach. MAIN RESULTS: We included 30 RCTs enrolling 8165 participants in this review. Twenty-four trials were conducted in children in sub-Saharan Africa, and 21 trials were over 20 years old. Many studies were assessed as being at unclear risk of bias due to inadequate descriptions of study methods. PraziquantelOn average, a single 40 mg/kg dose of praziquantel reduced the proportion of people still excreting eggs in their urine by around 60% compared to placebo at one to two months after treatment (treatment failure: RR 0.42, 95% CI 0.29 to 0.59, 864 participants, seven trials, high quality evidence). The proportion of people cured with praziquantel varied substantially between trials, from 22.5% to 83.3%, but was higher than 60% in five of the seven trials. At one to two months following praziquantel treatment at 40 mg/kg, the mean number of schistosome eggs in the urine was reduced by over 95% in five out of six trials (678 participants, six trials, high quality evidence).Splitting praziquantel 40 mg/kg into two doses over 12 hours probably has no benefits over a single dose, and in a single trial of 220 participants the split dose caused more vomiting (RR 0.5, 95% CI 0.29 to 0.86) and dizziness (RR 0.39, 95% CI 0.16 to 0.94). MetrifonateA single dose of metrifonate 10 mg/kg reduced egg excretion (210 participants, one trial, at eight months), but was only marginally better than placebo at achieving cure at one month (RR 0.83, 95% CI 0.74 to 0.94, 142 participants, one trial). In a single trial comparing one, two and three doses, the absolute number of participants cured improved from 47% after one dose to 81% after three doses (93 participants, one trial, low quality evidence).Two small trials compared 40 mg/kg single dose praziquantel with two or three doses of 10 mg/kg metrifonate and found no clear evidence of differences in cure (metrifonate 2 x 10 mg/kg at one month: RR 1.03, 95% CI 0.8 to 1.34, 72 participants, one trial; metrifonate 3 x 10 mg/kg at three months: RR 0.33, 95% CI 0.07 to 1.57, 100 participants, one trial. In one trial both drugs performed badly and in one trial both performed well. Other drugsThree trials have evaluated the antimalarial artesunate; with inconsistent results. Substantial antischistosomal effects were only seen in one of the three trials, which was at unclear risk of bias due to poor reporting of the trial methods. Similarly, another anti-malarial mefloquine has been evaluated in two small trials with inconsistent effects.Adverse events were described as mild for all evaluated drugs, but adverse event monitoring and reporting was generally of low quality. AUTHORS' CONCLUSIONS: Praziquantel 40 mg/kg is the most studied drug for treating urinary schistosomiasis, and has the strongest evidence base.Potential strategies to improve future treatments for schistosomiasis include the combination of praziquantel with metrifonate, or with antimalarial drugs with antischistosomal properties such as artesunate and mefloquine. Evaluation of these combinations requires rigorous, adequately powered trials using standardized outcome measures.

Comparative efficacy of trichlorphon and trichlorphon/ivermectin combination treatment against anthelmintic-resistant cattle nematodes in Argentina.

Twenty-four Holando Argentino male calves were treated orally with 50 mg/kg body weight trichlorphon (TCF); 0.2 mg/kg body weight subcutaneous ivermectin (IVM); a combination of TCF+IVM at the same doses and administration routes; or remained untreated (control group). All calves were necropsied at day 14 post treatment for counting and identification of worms from abomasum, small and large intestines and lungs to determine the absolute efficacy (controlled efficacy test) for each treatment. Using the faecal egg count reduction test, the efficacy was 63.7 % for TCF, 72.3 % for IVM and 99.2 % for TCF+IVM. The absolute efficacy of IVM and IVM+TCF was 100 % against Haemonchus placei, Trichostrongylus axei and Ostertagia ostertagi (p < 0.05). TCF showed a similar level of efficacy except against O. ostertagi (84.7 %). Efficacy of the treatments against Cooperia oncophora/pectinata/mcmasteri was 80.4 % for IVM, 95.7 % for TCF and 99.6 % for TCF+IVM; against Trichostrongylus colubriformis was 79 % for IVM, 86.2 % for TCF and 94.1 % for TCF+IVM; against Nematodirus helvetianus was 0 % for IVM, 100 % for TCF and 93.8 % for TCF+IVM. The efficacies of TCF, IVM and TCF+IVM were 100 % against Oesophagostomum radiatum and Trichuris spp. The efficacy of TCF against Dictyocaulus viviparus was 52 % and 100 % for IVM and IVM+TCF, respectively. This is the first report of Trichostrongylus colubriformis and Nematodirus helvetianus resistant to ivermectin treatment in cattle of Argentina. The TCF+IVM combination could be an alternative for the control and treatment of nematode infections including IVM-resistant strains.

The efficacy of trichlorphon and naphthalophos against multiple anthelmintic-resistant nematodes of naturally infected sheep in Argentina.

An anthelmintic efficacy trial was conducted in sheep harbouring anthelmintic-resistant worms in Argentina. Seventy lambs were selected from a flock that had been grazed on pastures infected with trichostrongyles previously shown to be resistant to the main anthelmintic groups. Lambs were allocated to comparable groups of ten animals each and treated with trichlorphon (50 mg/kg body weight (b.w.) orally); naphthalophos (50 mg/kg b.w. orally); ivermectin (0.2 mg/kg b.w. subcutaneously); fenbendazole (5 mg/kg b.w. orally); levamisole (8 mg/kg b.w. subcutaneously) and closantel (10 mg/kg b.w. orally). There was also an untreated group. The dose selection was based on manufacturer's recommendations.Faecal samples were collected 0 and 10 days post treatment to estimate efficacy (faecal egg count reduction). Six animals from each group were necropsied at day 10 for enumeration/identification of worms from the abomasum, small and large intestines to determine the absolute efficacy of each agent (controlled efficacy test). Trichlorphon and naphthalophos were effective (> 99 %) against Haemonchus contortus (p < 0.05).Naphthalophos also showed efficacy against Trichostrongylus axei (99.3 %), Teladorsagia circumcincta (97.8 %), Trichostrongylus colubriformis (99.2 %), Cooperia punctata/curticei/pectinata (90.4 %), Nematodirus spathiger (89.2 %) and Oesophagostomum venulosum/columbianum (93.7 %). Fenbendazole and levamisole showed efficacy (> 95 %) against all nematodes except T. colubriformis. The efficacy of ivermectin was low against H. contortus (23 %) and Cooperia spp. (46.3 %). Closantel showed low efficacy against T. axei (64.4 %), H. contortus (80.6 %) and T. colubriformis (59.5 %).When anthelmintic resistance is widespread, trichlorphon treatment is appropriate if H. contortus is present; however, naphthalophos represents an effective therapeutic alternative for incorporation into worm control programmes.

Anthelmintics for people with neurocysticercosis.

BACKGROUND: Neurocysticercosis is an infection of the brain by the larval stage of the pork tapeworm. In endemic areas it is a common cause of epilepsy. Anthelmintics (albendazole or praziquantel) may be given to kill the parasites. However, there are potential adverse effects, and the parasites may eventually die without treatment. OBJECTIVES: To assess the effectiveness and safety of anthelmintics for people with neurocysticercosis. SEARCH STRATEGY: In May 2009 we searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (The Cochrane Library 2009, Issue 2), MEDLINE, EMBASE, LILACS, and the mRCT. SELECTION CRITERIA: Randomized controlled trials comparing anthelmintics with placebo, no anthelmintic, or other anthelmintic regimen for people with neurocysticercosis. DATA COLLECTION AND ANALYSIS: Two authors independently selected trials, extracted data, and assessed each trial's risk of bias. We calculated risk ratios (RR) for dichotomous variables, with 95% confidence intervals (CI). We pooled data from trials with similar interventions and outcomes. MAIN RESULTS: For viable lesions in children, there were no trials. For viable lesions in adults, no difference was detected for albendazole compared with no treatment for recurrence of seizures (116 participants, one trial); but fewer participants with albendazole had lesions at follow up (RR 0.56, 95% CI 0.45 to 0.70; 192 participants, two trials).For non-viable lesions in children, seizures recurrence was less common with albendazole compared with no treatment (RR 0.49, 95% CI 0.32 to 0.75; 329 participants, four trials). There was no difference detected in the persistence of lesions at follow up (570 participants, six trials). For non-viable lesions in adults, there were no trials.In trials including viable, non-viable or mixed lesions (in both children and adults), headaches were more common with albendazole alone (RR 9.49, 95% CI 1.40 to 64.45; 106 participants, two trials), but no difference was detected in one trial giving albendazole with corticosteroids (116 participants, one trial). AUTHORS' CONCLUSIONS: In patients with viable lesions, evidence from trials of adults suggests albendazole may reduce the number of lesions. In trials of non-viable lesions, seizure recurrence was substantially lower with albendazole, which is counter-intuitive. It may be that steroids influence headache during treatment, but further research is needed to test this.

Anthelmintics for people with neurocysticercosis.

BACKGROUND: Neurocysticercosis is an infection of the brain by the larval stage of the pork tapeworm. In endemic areas it is a common cause of epilepsy. Anthelmintics (albendazole or praziquantel) may be given to kill the parasites. However, there are potential adverse effects, and the parasites may eventually die without treatment. OBJECTIVES: To assess the effectiveness and safety of anthelmintics for people with neurocysticercosis. SEARCH STRATEGY: In May 2009 we searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (The Cochrane Library 2008, Issue 3), MEDLINE, EMBASE, LILACS, and the mRCT. SELECTION CRITERIA: Randomized controlled trials comparing anthelmintics with placebo, no anthelmintic, or other anthelmintic regimen for people with neurocysticercosis. DATA COLLECTION AND ANALYSIS: Two authors independently selected trials, extracted data, and assessed each trial's risk of bias. We calculated risk ratios (RR) for dichotomous variables, with 95% confidence intervals (CI). We pooled data from trials with similar interventions and outcomes. MAIN RESULTS: For viable lesions in children, there were no trials. For viable lesions in adults, no difference was detected for albendazole compared with no treatment for recurrence of seizures (116 participants, one trial); but fewer participants with albendazole had lesions at follow up (RR 0.56, 95% CI 0.45 to 0.70; 192 participants, two trials).For non-viable lesions in children, seizures recurrence was less common with albendazole compared with no treatment (RR 0.49, 95% CI 0.32 to 0.75; 329 participants, four trials). There was no difference detected in the persistence of lesions at follow up (570 participants, six trials). For non-viable lesions in adults, there were no trials.In trials including viable, non-viable or mixed lesions (in both children and adults), headaches were more common with albendazole alone (RR 9.49, 95% CI 1.40 to 64.45; 106 participants, two trials), but no difference was detected in one trial giving albendazole with corticosteroids (116 participants, one trial). AUTHORS' CONCLUSIONS: In patients with viable lesions, evidence from trials of adults suggests albendazole may reduce the number of lesions. In trials of non-viable lesions, seizure recurrence was substantially lower with albendazole, which is counter-intuitive. It may be that steroids influence headache during treatment, but further research is needed to test this.

Anthelmintic efficacy of oral trichlorfon solution against ivermectin resistant nematode strains in cattle.

Infected calves from two different rural estates in Brazil were studied to assess the anthelmintic efficacy of oral trichlorfon against naturally occurring ivermectin resistant parasitic nematode strains. In experiment I, infected animals were from a region where ivermectin resistant populations of Haemoncus placei, Cooperia punctata, Cooperia spatulata and Trichuris discolor have recently been identified. Six calves with natural gastrointestinal nematode infections were treated with 48.5mg/kg aqueous trichlorfon administered orally and six calves acted as a non-treated control group. In experiment II 24 naturally infected calves were selected to enter one of four treatment groups, six animals each received: 48.5mg/kg oral trichlorfon; 200 microg/kg subcutaneous 1% ivermectin; 630 microg/kg subcutaneous 3.15% ivermectin; or no treatment (control group). Gastrointestinal helminths were counted and identified post-mortem at 7 days (trichlorfon and 1% ivermectin treated and untreated animals) or 14 days (3.15% ivermectin treated and untreated animals) after administration of the test agents. Experiment I identified a high level efficacy for oral trichlorfon against four helminth species that have previously been shown to be ivermectin resistant in this geographical region: percentage efficacy was 99.82% against adult H. placei, 99.18% against C. punctata, 99.33% against C. spatulata, 81.06% against T. axei, 98.46% against Oesophagostomum radiatum and 100% against T. discolor. Trichlorfon also showed activity against the ivermectin (1% and 3.15%) resistant helminth species identified in experiment II, attaining efficacy levels of 99.17% against H. placei, 98.46% against C. punctata and 100.00% against T. discolor. These findings indicate that oral trichlorfon is an effective treatment option in the management of cattle infected with ivermectin resistant helminths.

In vitro reactivation of trichlorfon-inhibited butyrylcholinesterase using HI-6, obidoxime, pralidoxime and K048.

Trichlorfon is a specific inhibitor of cholinesterases. It was typically used as an insecticide; however, trichlorfon was described as useful for symptomatic treatment of Alzheimer's disease some years ago. The presented study is aimed at reactivation of trichlorfon-inhibited butyrylcholinesterase since this enzyme play an important role in Alzheimer's disease as deputy for acetylcholinesterase and furthermore it could be applied as a scavenger in case of overdosing. We used in vitro reactivation test for considering only reactivation efficacy of butyrylcholinesterase that is inhibited by trichlorfon and not reactivation of butyrylcholinesterase inhibited by trichlorfon metabolic products. Four reactivators were used: HI-6, pralidoxime, obidoxime, and K048. Although all of the reactivators seem to be effective at 1 mM concentration, a lower concentration was not able ensure sufficient reactivation. There was also an observed lowering of reactivation efficacy when butyrylcholinesterase was exposed to trichlorfon for a longer time interval.

Drugs for treating urinary schistosomiasis.

BACKGROUND: Urinary schistosomiasis causes long-term ill-health. This review examines the various treatment options and newer drugs. OBJECTIVES: To evaluate antischistosomal drugs, used alone or in combination, for treating urinary schistosomiasis. SEARCH STRATEGY: In August 2007, we searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (The Cochrane Library 2007, Issue 3), MEDLINE, EMBASE, LILACS, mRCT, and reference lists of articles. We also contacted experts in schistosomiasis research. SELECTION CRITERIA: Randomized and quasi-randomized controlled trials of praziquantel, metrifonate, artemisinin derivatives, or albendazole, alone or in combination, versus placebo, different doses, or other antischistosomal drugs for treating urinary schistosomiasis. DATA COLLECTION AND ANALYSIS: One author extracted data, and assessed eligibility and methodological quality, which were cross-checked by a second person. Dichotomous outcomes were combined using risk ratio (RR), and continuous data were combined using weighted mean difference (WMD); both presented with 95% confidence intervals (CI). MAIN RESULTS: Twenty-four trials (6315 participants) met the inclusion criteria. Compared with placebo, participants receiving metrifonate had fewer parasitological failures at follow up at one to three months (1 trial) and three to 12 months (3 trials). Egg reduction rate was over 90%, and no adverse events were reported (1 trial). One metrifonate dose was inferior to three doses given fortnightly (both used 10 mg/kg). Praziquantel (standard single 40 mg/kg oral dose) was more effective than placebo at reducing parasitological failure at one to three months' follow up and three to 12 months. Egg reduction rates were improved with praziquantel (over 95% versus 5.3% to 64% with placebo). Mild to moderate adverse events were recorded in two trials. A comparison of metrifonate (10 mg/kg x 3, once every 4 months for one year) with praziquantel (standard dose) showed little difference in parasitological failure. For praziquantel, there was no significant difference in effect between 20 mg/kg x 2, 30 mg/kg x 1, and 20 mg/kg x 1, and the standard dose for all outcomes. One small trial of artesunate showed no obvious benefit compared with placebo, and the artesunate-praziquantel combination was similar to praziquantel alone. AUTHORS' CONCLUSIONS: Praziquantel and metrifonate are effective treatments for urinary schistosomiasis and have few adverse events. Metrifonate requires multiple administrations and is therefore operationally less convenient in community-based control programmes. Evidence on the artemisinin derivatives is currently inconclusive, and further research is warranted on combination therapies. We suggest metrifonate be reconsidered for the WHO Model List of Essential Medicines.

WITHDRAWN: Drugs for treating neurocysticercosis (tapeworm infection of the brain).

BACKGROUND: Anthelminthic drugs may shrink brain cysts in neurocysticercosis, but can also cause severe adverse effects. OBJECTIVES: The objective of this review was to assess the effects of drug treatment in human neurocysticercosis in relation to survival, cyst persistence, subsequent seizures and hydrocephalus. SEARCH STRATEGY: We searched the Cochrane Infectious Diseases Group specialized trials register (September 2002), The Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 3, 2002), MEDLINE (1966 to September 2002), EMBASE (1980 to August 2002), LILACS (September 2002). We contacted researchers and experts in the field, and pharmaceutical companies. SELECTION CRITERIA: Randomised or quasi-randomised trials comparing a cysticidal drug with a placebo or a control group receiving symptomatic therapy, in patients with neurocystercosis. DATA COLLECTION AND ANALYSIS: Assessment of trial quality and data extraction was done independently by two reviewers. MAIN RESULTS: Four studies involving 305 people met the inclusion criteria. None reported on withdrawal of anticonvulsant therapy, headache relief, disability or death as outcomes. A difference just approaching significance was detected between cysticidal therapy and placebo in relation to cyst persistence up to six months (relative risk 0.83, 95% confidence interval 0.70 to 0.99). Two trials reported on seizures after one to two years follow-up and found no difference (relative risk 0.95, 95% 0.59 to 1.51). There was no difference detected for hydrocephalus (relative risk 2.19, 95% confidence interval 0.29 to 16.55). AUTHORS' CONCLUSIONS: There is insufficient evidence to assess whether cysticidal therapy in neurocysticerosis is associated with beneficial effects.

Impact of the botanical insecticide Neem Azal on survival and reproduction of the biting louse Damalinia limbata on angora goats.

Secondary metabolites present in the neem tree (Azadirachta indica A. Juss, Meliaceae), exhibit a wide range of biological activities in insects. However, few studies have been undertaken to assess the potential of neem products as insecticides for the control of ectoparasites of domestic animals. This study was undertaken to estimate the efficacy of Neem Azal, an azadirachtin-rich extract of neem seeds, in controlling Damalinia limbata (Phthiraptera) louse infestation of angora goats. The study was conducted on a fibre animal farm situated in Central Italy. Groups of 11-12 goats were treated with Neem Azal at an azadirachtin concentration of 650ppm or 125ppm, with Neguvon or were left untreated. Their louse burden was assessed fortnightly to monthly for 22 weeks. A reduction in louse densities of 76-96% was observed from week 2 to week 18 after treatment with the neem solution containing azadirachtin at a concentration of 650ppm. At the lower test concentration (125ppm) a reduction of 60-92% could be recorded from week 2 to week 14. Neem Azal was found to reduce the survival of both adult and nymph stages of D. limbata and to interfere with oviposition and oogenesis of female lice. A decrease in oviposition was observed in neem exposed female lice and the examination of their ovaries revealed morphological alterations in both vitellogenic and previtellogenic ovarioles at the follicular and germinal level. Since neem compounds target different life stages and physiological processes of D. limbata, the development of insecticide resistance by biting lice exposed to neem-based insecticides appears unlikely. For this reason and for its prolonged activity, which in principle allows angora goats to be protected for a large part of the mohair production cycle, neem-based insecticides may have a potential interest for mohair producing breeders.

Metrifonate for Alzheimer's disease.

BACKGROUND: Metrifonate is a long-acting irreversible cholinesterase inhibitor, originally used to treat schistosomiasis. Its potential to enhance central nervous system cholinergic neurotransmission led to clinical trials for the treatment of people with Alzheimer's disease (AD). Although low incidence of serious side effects occurred during short-term use as an antihelmintic, in studies of the treatment of AD extending over 6 months, 20 patients experienced respiratory paralysis and problems with neuromuscular transmission. These findings have led to a halt to trials of metrifonate for AD and Bayer, the pharmaceutical company, has withdrawn its FDA application. OBJECTIVES: 1) To establish the efficacy of metrifonate for patients with Alzheimer's disease, in terms of cognition, global impression, functional activity, non cognitive symptoms, rate of institutionalization and mortality.2) Assess the safety and tolerability of metrifonate. SEARCH STRATEGY: The Cochrane Dementia and Cognitive Improvement Group's Specialized Register was searched on 5 December 2005 using the term metrifonat*. This Register is regularly updated with records from all major health care databases (MEDLINE, EMBASE, CINAHL, PsycINFO) and many trials databases. One of the authors (LS), as member of the Metrifonate Study Group has had the opportunity to contact other metrifonate trialists to obtain data from potentially non published data of metrifonate clinical trials. SELECTION CRITERIA: All unconfounded, randomized double-blind clinical controlled trials comparing metrifonate to placebo in people with AD. DATA COLLECTION AND ANALYSIS: Data were extracted by the two reviewers, cross-checked, and pooled when appropriate and possible. MAIN RESULTS: Most studies assessed changes in cognitive function, global function, activities of daily living, behavioural problems, severity of disease and adverse events. Occasionally the results were not reported in sufficient detail to allow extraction of data for the meta-analyses. The treatment regimens were varied: loading doses were used in some trials. The range of maintenance doses and studies were not pooled unless the treatment regimens were considered comparable. The lengths of treatment varied from 6 to 26 weeks and studies were not pooled unless the treatment duration was similar. The results are derived from the ITT populations. Metrifonate at various doses, fixed and loading doses, was associated with significant cognitive improvement compared to placebo, except for weekly doses where there was no difference from placebo: MMSE (metrifonate 60-80 mg/day with initial loading at 26 weeks; metrifonate 50 mg/day fixed dose with no initial loading at 26 weeks MD 1.85, 95% CI 1.06 to 2.64, p<0.00001); ADAS-Cog (metrifonate 60-80 mg/day with initial loading at 26 weeks MD -3.24, 95% CI -4.40 to -2.08, p<0.00001)In most trials, there was improvement in clinical global impression: CIBIC-Plus (metrifonate 30-55 mg/day, approximately 0.65 mg/kg body weight, with initial loading at 26 weeks MD -0.25, 95% CI -0.41 to -0.09 p=0.002; metrifonate 50 mg/day fixed dose with no initial loading at 26 weeks MD -0.20, 95% CI -0.39 to -0.01, p=0.04). There were generally-significant drug-placebo differences in activities of daily living but this often depended on sample size and the characteristics of the instrument used: DAD (metrifonate 30-55 mg/day, 0.65 mg/kg body weight, with initial loading at 26 weeks MD 2.72, 95% CI 0.66 to 4.77, p=0.01; metrifonate 50 mg/day fixed dose with no initial loading at 26 weeks MD 4.07, 95% CI 0.29 to 7.85, p=0.03)Also there were differences associated with metrifonate compared with placebo for different doses of metrifonate in scores on a behavioural symptom scale, caregiver burden scale, and severity of disease scale. Adverse events occurring more often with metrifonate included abdominal pain, bloating, bradycardia, diarrhoea, leg cramps, nausea and rhinitis and were described as mostly mild and transient, but occasionally moderately severe, and infrequently severe and serious. Analysis of the number of patients suffering at least one mild, moderate, severe or serious adverse event before the end of treatment showed that there was usually no difference between placebo and metrifonate. AUTHORS' CONCLUSIONS: Metrifonate given once per day appears to be related to clinical response in cognition, global improvement, and activities of daily living in patients with mild to moderate Alzheimer's disease. Tolerability is good with adverse events as expected from a cholinesterase inhibitor, but with a low incidence of neuromuscular dysfunction and respiratory failure, too low to be detected in this review. It has been withdrawn from further development.

Pharmacological and molecular enhancement of learning in aging and Alzheimer's disease.

When animals learn hippocampus-dependent associative and spatial tasks such as trace eyeblink conditioning and the water maze, CA1 hippocampal neurons become more excitable as a result of reductions in the post-burst, slow afterhyperpolarization. The calcium-activated potassium current that mediates this afterhyperpolarization is activated by the calcium influx that occurs when a series of action potentials fire and serves as a modulator of neuronal firing frequency. As a result, spike frequency accommodation is also reduced after learning. Neuronal calcium buffering processes change and/or voltage-dependent calcium currents increase during aging; leading to enhancements in the slow afterhyperpolarization, increased spike frequency accommodation and age-associated impairments in learning. We describe a series of studies done to characterize this learning-specific enhancement in intrinsic neuronal excitability and its converse in aging brain. We have also combined behavioral pharmacology and biophysics in experiments demonstrating that compounds that increase neuronal excitability in CA1 pyramidal neurons also enhance learning rate of hippocampus-dependent tasks, especially in aging animals. The studies reviewed here include those using nimodipine, an L-type calcium current blocker that tends to cross the blood-brain barrier; metrifonate, a cholinesterase inhibitor; CI1017, a muscarinic cholinergic agonist; and galantamine, a combined cholinesterase inhibitor and nicotinic agonist. Since aging is the chief risk factor for Alzheimer's disease, a disease that targets the hippocampus and associated brain regions and markedly impairs hippocampus-dependent learning, these compounds have potential use as treatments for this disease. Galantamine has been approved by the USDA for this purpose. Finally, we have extended our studies to the TG2576 transgenic mouse model of Alzheimer's disease (AD), that overproduces amyloid precursor protein (APP) and increases levels of toxic beta-amyloid in the brain. Not only do these mice show deficits in hippocampus-dependent learning as they age, but their hippocampal neurons show a reduced capacity to increase their levels of intrinsic excitability with reductions in the slow afterhyperpolarization after application of the muscarinic agonist carbachol. These TG2576 APP overproducing mice were crossed with BACE1 knockout mice, that do not produce beta-amyloid because cleavage of APP by the beta-site APP cleaving enzyme 1 (BACE1) is a critical step in its formation. Not only was hippocampus-dependent learning rescued in the bigenic TG2576-BACE1 mice, but the capacity of hippocampal neurons to show normal enhancements of intrinsic excitability was restored. The series of studies reviewed here support our hypothesis that enhancement in intrinsic excitability by reductions in calcium-activated potassium currents in hippocampal neurons is an important cellular mechanism for hippocampus-dependent learning.

Modulation of cholinergic transmission enhances excitability of hippocampal pyramidal neurons and ameliorates learning impairments in aging animals.

Four cholinesterase inhibitors have been approved by the US Food and Drug Administration for treating behavioral symptoms of Alzheimer's disease. Here we review our experiences with two cholinesterase inhibitors (metrifonate and galanthamine) and a muscarinic acetylcholine receptor agonist (CI-1017) in behavioral pharmacological and brain slice experiments in aging and young rabbits. Aging rabbits are impaired in their ability to acquire the hippocampus-dependent trace eyeblink conditioning task, as compared to young controls. A large proportion of aging animals cannot reach behavioral criterion in this task. Those that do learn, do so more slowly. In addition, the post-burst afterhyperpolarization and spike frequency accommodation is increased in hippocampal pyramidal neurons from aging animals, i.e., cellular excitability is reduced as compared to those from young animals. Metrifonate, galanthamine, and CI-1017 reduced the learning deficits observed in aging rabbits so that they learned almost as quickly as young controls. These cholinergic compounds also enhanced the postsynaptic excitability of hippocampal pyramidal neurons in vitro. Therefore, we propose that the amelioration of learning impairment with the cholinergic compounds may in part be due to the enhanced excitability of hippocampal pyramidal neurons. The potential relevance of our studies to further understanding the cellular and behavioral changes that occur with normal aging and Alzheimer's Disease is discussed.

Effect of a treatment with eprinomectin or trichlorfon on the yield and quality of milk produced by multiparous dairy cows.

The effects of a strategic antiparasitic treatment against Hypoderma species and other parasites on the milk yield, composition, and somatic cell counts of 742 multiparous dairy cattle were investigated on 79 farms in a Hypoderma species-endemic area in western Switzerland; 357 of the cows were treated with eprinomectin, 252 with trichlorfon, and 133 were left untreated. The treatments were given between October and early December 1998, on average 53 days before calving. Milk yield, fat, protein and somatic cell counts were measured once a month until the end of lactation. Eprinomectin and trichlorfon significantly increased milk yield during the first month after treatment compared with the control cows by 2.14 (P < 0.001) and 2.50 kg per day (P < 0.001), respectively. Initially, the difference between the eprinomectin- and trichlorfon-treated animals was not significant, but the effect of eprinomectin on milk yield was persistent, whereas the effect of trichlorfon decreased significantly by 0.12 kg per day per month (P < 0.05). The somatic cell counts increased significantly slower in the treated cows than in the control cows (P < 0.05). Milk composition was not affected by the treatments.

The effects of long-term treatment with metrifonate, a cholinesterase inhibitor, on cholinergic activity, amyloid pathology, and cognitive function in APP and PS1 doubly transgenic mice.

Recent studies in cell cultures have shown that modulating the cholinergic activity can influence the processing and metabolism of amyloid precursor protein (APP). To investigate whether acetylcholinesterase inhibitors (ChEIs) could decrease production of amyloid beta-peptide (A(beta)) and slow down the accumulation of A(beta) also in vivo, we chronically administered metrifonate (100 mg/kg, po), a second-generation ChEI, to 7-month-old doubly transgenic APP+PS1 mice and their nontransgenic littermate controls for 7 months. Behavioral studies, including open field test, T maze, and water maze, were conducted after 6 months treatment with metrifonate, and the mice were sacrificed at the age of 14 months for biochemical and histological analyses. The long-term treatment with metrifonate failed to inhibit the marked overproduction and deposition of A(beta) in the APP+PS1 mice; in contrast, it increased both A(beta)40 and A(beta)42 levels in the hippocampus. However, the A(beta)42 to 40 ratio was significantly reduced by the treatment. In addition, the number of amyloid plaques in the hippocampus did not differ between the treatment and the control groups. Tolerance to cholinesterase inhibition might be induced in the mouse brain because the inhibition rate of AChE was attenuated from about 80 to 50% during the experiment in both APP+PS1 and nontransgenic mice. The metrifonate treatment did not affect cognitive testing parameters but reduced swimming speed and locomotor activity in both genotypes. Our results do not support the idea that ChEIs would slow down the progression of amyloid pathology in Alzheimer's disease.

Efficacy of metrifonate in improving the psychiatric and behavioral disturbances of patients with Alzheimer's disease.

Neuropsychiatric and behavioral symptoms are frequent and problematic components of Alzheimer's disease (AD). In two previously reported studies, metrifonate was shown to benefit behavioral symptoms as assessed by the Neuropsychiatric Inventory (NPI). In this post hoc analysis, detailed studies were completed to determine the effects of metrifonate on individual symptoms. This study was a retrospective analysis of pooled NPI data from two double-blind, placebo-controlled, multicenter 26-week studies of metrifonate that had achieved similar levels of cholinesterase inhibition. Mild-to-moderate probable AD patients received placebo (n = 222) or metrifonate (n = 450) 30 to 60 mg by weight or a 50-mg fixed dose once daily. At 26 weeks, metrifonate-treated patients had significantly reduced NPI total scores (P = .001) and fewer neuropsychiatric symptoms when compared with placebo-treated patients, including hallucinations (P = .004), agitation/aggression (P = .006), depression/dysphoria (P = .011), apathy (P = .019), and aberrant motor behavior (P = .008). Metrifonate reduced or stabilized neuropsychiatric disturbances in 60% of symptomatic patients. Almost 40% of metrifonate-treated patients had a clinically relevant reduction (> or = 30% decrease in NPI score) in their neuropsychiatric disturbances (P = .002). High proportions of metrifonate-treated patients manifested clinically relevant reductions in anxiety (58%, P = .009), apathy (51%, P = .020), and depression/dysphoria (50%, P = .021) compared to placebo. The metrifonate-associated reductions in NPI scores were evident by week 12 and were maintained for the 26-week study period. There was an overall effect size of metrifonate of approximately 15% on total NPI scores when compared to placebo. Metrifonate significantly reduced many of the psychiatric and behavioral symptoms of AD. The observations suggest that enhancement of cholinergic functions in AD has beneficial effects on behavior.