Effect of parasitism on the pharmacokinetic disposition of ivermectin in lambs.

The aim of this study was to investigate the effect of parasitism on plasma availability and pharmacokinetic behaviour of ivermectin (IVM) in lambs. Fourteen greyface Suffolk lambs (26.8 +/- 2.2 kg body weight) were selected for this study. Seven pairs of lambs were allocated into two groups in order to obtain an approximately even distribution. Group I (non-parasitized) was pre-treated by three repeated administrations of 5 mg/kg of fenbendazole (Panacur), in order to maintain a parasite-free condition. The lambs in group II (parasitized) did not receive any anthelmintic treatment and the natural infection was sustained by an oral inoculation of infective stages of nematode parasites. After the 85-day pre-treatment period both groups of animals were treated with IVM (200 microg/kg, Ivomec) by subcutaneous injection in the shoulder area. Both groups of animals were maintained under similar conditions of feeding and management. Blood samples were collected by jugular puncture at different times between 0.5 h and 25 days post-treatment. After plasma extraction and derivatization, samples were analysed by high-performance liquid chromatography with fluorescence detection. A computerized kinetic analysis was performed and data were compared using the unpaired Student's t-test. The parent molecule was detected in plasma between 30 min and either 12 (parasitized) or 20 (no parasitized) days post-IVM treatment. The area under the curve values of the parasitized group (75.2 +/- 15.5 ng x d/ml) were significantly lower that those observed in the parasite-free group (134.3 +/- 15.7 ng x d/ml). The mean residence time (MRT) of the parasitized group (2.93 +/- 0.16 days) was significantly lower than the MRT of healthy group (3.93 +/- 0.29 days). The results of this study have shown that a change in body condition followed by a parasitic infection is associated with significant changes in plasma disposition of IVM when it is administered subcutaneously to parasitized lambs. Therefore, variations in the condition induced by parasitism should be considered when these anthelmintics are used for treating parasitized animals.

Plasma profiles of ivermectin in horses following oral or intramuscular administration.

A study was undertaken in order to evaluate and compare ivermectin's (IVM) plasma disposition kinetic parameters after oral or intramuscular (IM) administration in horses. Ten clinically healthy adult horses, weighing 380-496 kg body weight (BW), were allocated to two experimental groups of five horses. Group I, was treated with an oral paste formulation of IVM at the manufacturer's recommended dose of 0.2 mg/kg BW. Group II, was treated IM with an injectable 1% formulation of IVM at a dose of 0.2 mg/kg BW. Blood samples were collected by jugular puncture at different times between 0.5 h and 75 days post-treatment. After plasma extraction and derivatization, samples were analysed by high-performance liquid chromatography with fluorescence detection. A computerized kinetic analysis was performed, and data were compared using the Wilcoxon signed rank test. The parent molecule was detected in plasma between 30 min and either 20 (oral) or 40 (IM) days post-treatment. Significant differences were found for the time corresponding to peak plasma concentrations (tmax) and for absorption half-life. Peak plasma concentrations (Cmax) of 51.3 +/- 16.1 ng/ml (mean +/- SD) were obtained after oral administration and of 31.4 +/- 6.0 ng/ml for the IM route. The values for area under concentration-time curve were 137.1 +/- 35.9 ng day/ml for the group treated orally, and 303.2 +/- 4.3 ng day/ml for the IM treated group. The mean plasma residence times were 4.2 +/- 0.4 and 8.9 +/- 0.7 days for oral and IM-treated groups, respectively. The results of this study show that the route of administration considerably affects the disposition of IVM. A significant difference in bioavailabilty and half-life of elimination of IVM was observed after IM administration compared with oral administration. A close relationship between pharmacokinetic profiles and the clinical efficacy of IVM was established.

Pharmacokinetics of doramectin and ivermectin after oral administration in horses.

A study was undertaken in order to compare plasma disposition kinetic parameters of doramectin (DRM) and ivermectin (IVM) in horses after oral administration. Ten crossbreed adult horses, clinically healthy, weighing 380-470 kg body weight (bw) were selected for study. Faecal examinations were performed to determine faecal parasite egg counts. Horses were allocated to two groups of five animals to provide an even distribution considering the variables sex, body weight and faecal egg count. Group I, were treated with an oral paste formulation of IVM at 0.2 mg/kg b/w and Group II, were treated with an oral dose of 0.2 mg/kg bw of DRM prepared as paste from the injectable formulation for oral administration. Blood samples were collected by jugular puncture between 0 h and 75 days post-treatment. Plasma was separated and later solid phase extraction and derivatization samples were analysed by high performance liquid chromatography (HPLC); a computerised kinetic analysis was carried out. Data were compared using the Mann-Whitney U-test. The mean plasma concentrations of DRM and IVM after oral administration in horses were detected until 30 and 20 days, respectively. Both drugs showed similar patterns of absorption and no significant differences were found for peak concentration, the time to peak concentration, or for absorptive half-life. The terminal elimination half-life was significantly (P<0.05) longer in the DRM treated group than for the IVM treated group. The differences observed in the elimination half-life explain the longer mean residence time and high values of area under the concentration time curve for the group treated with DRM, which are 30% higher than those of the IVM group. Considering its pharmacokinetics, tolerance and anthelmintic efficacy, the oral administration of DRM, could be an alternative to IVM for the control of parasitic diseases of horses.

Diagnosis of Chlamydia pneumoniae in community-acquired pneumonia in children in Chile.

UNLABELLED: The incidence of Chlamydia pneumoniae in community-acquired pneumonia in children was studied prospectively in 112 children aged 1 mo to 14 y. Diagnosis of C. pneumoniae was performed by polymerase chain reaction (PCR) on nasopharyngeal aspirates and serology by the microimmunofluorescence test on a single serum specimen. Three (2.7%) cases of pneumonia due to this agent were diagnosed by both PCR and serology. C. pneumoniae was not found in any of 62 children below 5 y of age. In the age group 5-8 y, only 1/30 (3%) was found positive, and in the age group 9-14 y, C. pneumoniae was diagnosed in 2/20 (10%) children. CONCLUSION: Although the number of enrolled patients is small, and the diagnostic techniques used may have some limitations, the results of this study suggest that C. pneumoniae.plays a minor role in the aetiology of pneumonia in children less than 9 y of age in our country. However, it should be considered as a potential agent in pneumonia in older children.

Randomized trial of salbutamol via metered-dose inhaler with spacer versus nebulizer for acute wheezing in children less than 2 years of age.

The aim of this study was to compare the efficacy of salbutamol delivered via a metered-dose inhaler with a spacer and facial mask (MDI-S) vs. a nebulizer (NEB) for the treatment of acute exacerbations of wheezing in children. In a single-blind, prospective, randomized clinical trial, 123 outpatients (1-24 months of age), presenting with "moderate to severe" wheezing, were seen in the emergency department. Children were randomly assigned to one of two salbutamol treatment groups. In the first hour, the MDI-S group received 2 puffs (100 microg/puff) every 10 min for 5 doses, and the NEB group received 0.25 mg/kg every 13 min for 3 doses. If the clinical score was >5 at the end of the first hour, the patients received another hour of the same treatment and also betamethasone (0.5 mg/kg intramuscular). On enrollment and after the first and the second hour of treatment each child had a validated clinical score assigned by a blinded investigator. There were no differences at the time of admission to the emergency department between groups in clinical score or demographic data. Success (clinical score 0.05). We conclude that in this study population, children less than 2 years of age with moderate-severe exacerbations of wheezing responded faster to salbutamol delivered by MDI with a spacer and facial mask than to salbutamol delivered by nebulizer.

Comparison of the pharmacokinetics of moxidectin (Equest) and ivermectin (Eqvalan) in horses.

A study was undertaken in order to evaluate and compare plasma disposition kinetic parameters of moxidectin and ivermectin after oral administration of their commercially available preparations in horses. Ten clinically healthy adult horses, weighing 390-446 kg body weight (b.w.), were allocated to two experimental groups of five horses. Group I was treated with an oral gel formulation of moxidectin (MXD) at the manufacturers recommended therapeutic dose of 0.4 mg/kg bw. Group II was treated with an oral paste formulation of ivermectin (IVM) at the manufacturers recommended dose of 0.2 mg/kg b.w. Blood samples were collected by jugular puncture at different times between 0.5 h and 75 days post-treatment. After plasma extraction and derivatization, samples were analysed by HPLC with fluorescence detection. Computerized kinetic analysis was carried out. The parent molecules were detected in plasma between 30 min and either 30 (IVM) or 75 (MXD) days post-treatment. Both drugs showed similar patterns of absorption and no significant difference was found for the time corresponding to peak plasma concentrations or for absorption half-life. Peak plasma concentrations (Cmax) of 70.3+/-10.7 ng/mL (mean +/- SD) were obtained for MXD and 44.0+/-23.1 ng/mL for IVM. Moreover, the values for area under concentration-time curve (AUC) were 363.6+/-66.0 ng x d/mL for the MXD treated group, and 132.7+/-47.3 ng x d/mL for the IVM treated group. The mean plasma residence times (MRT) were 18.4+/-4.4 and 4.8+/-0.6 days for MXD and IVM treated groups, respectively. The results showed a more prolonged residence of MXD in horses as demonstrated by a four-fold longer MRT than for IVM. The longer residence and the higher concentrations found for MXD in comparison to IVM could possibly explain a more prolonged anthelmintic effect. It is concluded that in horses the commercial preparation of MXD presents a pharmacokinetic profile which differs significantly from that found for a commercial preparation of IVM. To some extent these results likely reflect differences in formulation and doses.

Relation between pulse oximetry and clinical score in children with acute wheezing less than 24 months of age.

The aim of this study was to determine the relation between transcutaneous hemoglobin oxygen saturation, measured by pulse oximetry (SpO2), and clinical score values in 138 infants (mean+/-SD, 6.6+/-5.5 months of age) with acute wheezing episodes presenting in a primary care outpatient setting. A single investigator evaluated the severity of the acute wheezing episodes by assigning a clinical score and was unaware of the SpO2 values. Another investigator measured SpO2 values on all subjects. The mean (+/-SD) SpO2 value was 98.2+/-1.1% for children with clinical scores of 2-5 (n = 32); 95.4+/-1.5% for those with scores of 6-7 (n = 82), and 92.9+/-2% for children with scores of 8-10 (n = 24), (P < 0.001 by Bonferroni's multiple comparison, when all two-way comparisons were done for each pair of results). The clinical score showed a good correlation with SpO2 (r = -0.76; 95% CI, -0.83 to -0.68). We conclude that if pulse oximetry is not available, it is advisable to include oxygen in the therapy of wheezy infants with clinical scores values >8.

Effects of winter supplementation and antiparasite treatment on the productive performance of milk herd in the central-south region of Chile.

During the winter of 1994, a survey of productive and reproductive parameters was undertaken in the south-central part of Chile (8th Region) on 71 cows provided by four small farms with low production (< 3000 l/year). A low food intake was recorded (8.6 +/- 0.2-12.4 +/- 0.2 kg DM/day) and, as a result, the cows calved with poor body condition score (1.9 +/- 0.04 points on the scale of one-to-five, had milk production between 10.5 +/- 0.4 and 12.8 +/- 0.6 l/day, had a delayed start of ovulatory activity (78.2 +/- 4.6 days) and an interval between calving and conception of 120.3 +/- 4.6 days. In addition, low levels of packed cell volume (PCV) and hemoglobin (HEM) were found, which were considered to be a combined effect of low feed ingestion and parastic infection by Fasciola hepatica. To improve the productive and reproductive parameters, treatments were undertaken in three of the four small farms; a parasiticide treatment was used against the F. hepatica at the beginning of the winter and the availability of forage was increased via the use of supplementary green oats. Spring crops were also cultivated: corn for silage and oats with peas to make hay. The antiparasite treatment and supplementation of forage was associated with better body condition score at calving, improved hematological parameters, increased milk production (17%), reduced number of days to conception (120 vs. 91) and increased conception rate at first service (36 vs. 60%). In the fourth small farm where no interventions were undertaken, the parameters obtained during 1994 remained unchanged.

[Frequency of human trichinosis in Concepción and Arauco, Chile: study in autopsied persons at the Concepción Medico-Legal Service. June 1996-March 1997]. / Frecuencia de triquinosis humana en Concepción y Arauco, Chile: estudio en personas autopsiadas en el Servicio Médico Legal de Concepción. Junio 1996-Marzo 1997.

The frequency of trichinosis was determined in 300 dead persons, residents in the provinces of Concepción and Arauco, and requiring necropsy at the Servicio Medico Legal of Concepción. Diaphragm muscle samples were taken from June 1996 to March 1997. The diagnosis was made by trichinoscopy and artificial digestion techniques. Five samples (1.67%) were positive. There was not differences between sexes. Positive cases were found mainly among 30 to 49 years old people belonging to middle-lower class. Both diagnostic techniques showed different sensitivity as a consequence of the parasitic load and on the contrary, the artificial digestion was less sensitive when the cyts were fully calcified.

[Gastrointestinal parasitism in the common partridge (Nothoprocta perdicaria) in the Nuble Zone, Chile]. / Parasitismo gastrointestinal en la perdiz común (Nothoprocta perdicaria) en la zona de Nuble, Chile.

A study on gastrointestinal parasitism in wild chilean partridges (Nothoprocta perdicaria) in the Nuble province (Chile) determined that 75% of birds were infected. The species Capillaria caudinflata, Subulura suctoria, Aploparaksis tinamoui and oocysts of Eimeria sp. were observed.

Treatment of Fasciola hepatica infection in horses with triclabendazole.

Thirteen thoroughbred foals with an adult infection and a presumed immature infection with Fasciola hepatica were treated with 12 mg triclabendazole/kg bodyweight. The absence of eggs from samples of faeces examined at intervals up to 110 days after treatment showed that all the animals were cured. In a second trial the same dose of triclabendazole cured 11 of 12 foals whereas nitroxynil at 7 mg/kg cured only six of 12 foals. No side effects were observed after treatment.