Pharmacokinetic and Adsorptive Analyses of Administration of Oral Voriconazole Suspension via Enteral Feeding Tube in Intensive Care Unit Patients

For intensive care unit (ICU) patients, injectable voriconazole (VRCZ) is difficult to use because the patients often develop acute kidney injury. Since many ICU patients have consciousness disturbance, oral ingestion of tablet formulation is also difficult, and administration of a suspension via enteral feeding tube is required when using VRCZ. In this study, we investigated the in vitro adsorption property of oral VRCZ to feeding tube and performed pharmacokinetic analysis of VRCZ prepared by powdering and simple suspension for ICU patients. VRCZ was tube-administered to five ICU patients at a loading dose of 300 mg and plasma VRCZ concentrations before and at 1, 2, 4, 8, 12 h after the first dose were measured using HPLC. Pharmacokinetic parameters were calculated by non-compartmental model analysis. The recovery rate of VRCZ after infusion of the suspension through feeding tube was 89.8 ± 8.3%, but the cumulative rates after the first and second re-infusion were 102.7 ± 20.7 and 99.3 ± 10.3%, respectively, suggesting almost no residual drug in the tube after re-infusion. Metabolic phenotype was extensive metabolizer (EM) in two patients and intermediate metabolizer (IM) in three patients. The values of total clearance (CL_tot/F) calculated by moment analysis were 0.51 and 0.55 L/h/kg in two EM patients, and 0.09, 0.29 and 0.31 L/h/kg in three IM patients. The CL_tot/F was apparently lower in IM patients compared to EM. In conclusion, powdered and suspended VRCZ administered via enteral feeding tube showed pharmacokinetics depending on CYP2C19 gene polymorphism, similar to that observed in usual oral administration.

Comparison of performance characteristics between high-performance liquid chromatography and latex agglutination turbidimetric immunoassay for therapeutic drug monitoring of zonisamide

Background

Recently, the Nanopia^® TDM Zonisamide reagent using the latex particle‐enhanced turbidimetric immunoassay (LTIA) method was developed. The aim of this study was to compare the differences in serum zonisamide (ZNS) concentrations quantified by the high‐performance liquid chromatography (HPLC) method and the LTIA method using a TBA‐25FR analyzer.

Methods

A total of 78 samples from 33 patients were quantified by both HPLC and LTIA methods. Deproteinization was used as pretreatment for the HPLC method. The ZNS concentrations quantified by two methods were compared.

Results

The HPLC method had intra‐ and inter‐day precision lower than 1.86% and 9.00%, and accuracy better than 2.44% and 6.33%, respectively. The LTIA method showed intra‐ and inter‐day precision lower than 2.50% and 5.20%, and accuracy better than 15.80% and 10.60%, respectively. The lower limits of quantification for the HPLC and LTIA methods were 1.0 and 5.0 µg/mL, respectively. The ZNS concentration quantified by the HPLC method correlated strongly with that by the LTIA method (r = 0.953, P < 0.001). A Bland‐Altman plot suggested no systematic error between ZNS concentrations quantified by HPLC and LTIA methods.

Conclusion

This study confirmed no differences between the concentrations quantified by the HPLC and LTIA methods at both high and low concentrations, demonstrating the confidence of measurement by the LTIA method.

Utilisation of the time constant calculated from heart rate recovery after exercise for evaluation of autonomic activity in horses

REASONS FOR PERFORMING STUDY

Heart rate (HR) recovery immediately after exercise is controlled by autonomic functions and the time constant (T) calculated from HR recovery is thought to be an index of parasympathetic activity in man.

OBJECTIVES

To investigate whether it is possible to evaluate autonomic function using the time constant in horses.

METHODS

Five Thoroughbred horses were subjected to a standard exercise test. Following pre-medication with saline, atropine and/or propranolol, the horses ran for 2.5 min at a speed of 8 m/sec at a 10% incline and T was calculated from HR after the exercise. Secondly, 7 Thoroughbred horses were then trained for 11 weeks and T and maximal oxygen uptake (VO2max) measured at intervals of 1 or 2 weeks. In 6 horses, T with atropine pre-medication was also measured before and after the whole training period. Furthermore, the HR variability at rest was evaluated by power spectral analysis at intervals of 3 or 4 weeks.

RESULTS

Time constant was increased by atropine and/or propranolol pre-medication, decreased with the progress of training and inversely correlated with VO2max during training (r = 0.43, P<0.005). Parasympathetic blockade significantly decreased T only after and not before, the training; however, T was lower in post training than in pretraining, irrespective of parasympathetic blockade. On the other hand, parasympathetic activity at rest was attenuated and sympathetic activity became predominant following the training.

CONCLUSION

Heart rate recovery is affected by sympathetic withdrawal and parasympathetic reactivation in horses and suggests that physical training hastened HR recovery by improving the parasympathetic function after exercise with aerobic capacity. However, the effects of other factors need to be considered because the training effect appeared on T even under parasympathetic blockade. The parasympathetic activity at rest is in contrast to that after exercise, suggesting that T does not reflect parasympathetic activity at rest.

POTENTIAL RELEVANCE

If demonstrated how HR recovery is controlled after exercise, its analysis will be important in the evaluation of physical fitness in horses.

Effect of uphill exercise on equine superficial digital flexor tendon forces at trot and canter

REASONS FOR PERFORMING STUDY

One cause of overstrain injury to the superficial digital flexor tendon (SDFT) in horses is the force loaded on the SDFT during repeated running. Therefore, decreasing this force may reduce SDFT injury. It has been reported that strain on the SDFT decreases with a toe-wedge shoe. Uphill courses are used for training of racehorses, and the angle of hoof-sole to the horizon during uphill running is similar to that of the toe-wedge shoe.

OBJECTIVES

To determine the effects of uphill exercise on the force on the SDFT during trotting and cantering.

METHODS

Arthroscopically implantable force probes (AIFP) were implanted into the SDFT of the left or right forelimb of 7 Thoroughbred horses and AIFP output recorded during trotting and cantering on a treadmill inclined at slopes of 0, 3 or 8%, and then 0% again. Superficial digital flexor tendon force was calculated as a relative value, with the amplitude of AIFP output voltage at initial 0% slope equal to 100.

RESULTS

Out of 14 sets of experiments, AIFP data were analysed successfully in 9 at the trot, in 3 at the canter in the trailing forelimb on a slope of 3 and 8%, and in 2 at the canter in the leading forelimb on a slope of 3%. Increasing the incline from 0-8% tended to decrease peak force in the SDFT at the trot, and in the trailing forelimb at the canter. However, force in the SDFT was unchanged in the leading forelimb at the canter on the 3% incline.

CONCLUSIONS

The force in the SDFT trotting or cantering uphill is unchanged or lower than that loaded at the same speed on a flat surface. Because at similar speeds the workload for uphill exercise is greater than on the flat, uphill running increases exercise intensity without increasing force in the SDFT.

POTENTIAL RELEVANCE

Uphill exercise may reduce the risk of SDFT injury as both running speed and SDFT force are decreased on an incline as compared to the flat, even when exercise intensity is the same. Further study is needed to confirm these findings at canter in a larger population of horses.

Effect of controlled exercise on middle gluteal muscle fibre composition in Thoroughbred foals

REASONS FOR PERFORMING STUDY

Most racehorses are trained regularly from about age 18 months; therefore, little information is available on the effect of training in Thoroughbred foals.

HYPOTHESIS

Well-controlled exercise could improve muscle potential ability for endurance running.

METHODS

Thoroughbred foals at age 2 months were separated into control and training (treadmill exercise) groups and samples obtained from the middle gluteal muscle at 2 and 12 months post partum. Muscle fibre compositions were determined by histochemical and electrophoretical techniques and succinic dehydrogenase (SDH) activity was analysed in each fibre type.

RESULTS

All fibre types were hypertrophied with growth and type I and IIA fibres were significantly larger in the training than the control group at age 12 months. A significant increase of SDH activity was found in type IIX muscle fibres in the training group.

CONCLUSIONS

Training in young Thoroughbred horses can facilitate muscle fibre hypertrophy and increase the oxidative capacity of type IIX fibres, which could potentially enhance stamina at high speeds.

POTENTIAL RELEVANCE

To apply this result to practical training, further studies are needed to determine more effective and safe intensities of controlled exercise.

Effect of detraining on cardiorespiratory variables in young thoroughbred horses

REASONS FOR PERFORMING STUDY

Thoroughbred racehorses often experience interruptions to their training. Identifying the effects of these changes and how they alter athletic performance might provide an insight on to how to prevent these changes from occurring.

HYPOTHESIS

Training and detraining young Thoroughbreds alters their aerobic capacities with correlated changes in circulatory capacities; if horses remained spontaneously active in a pasture during their detraining period, their decreases in aerobic capacity during detraining would be reduced.

METHODS

We trained 6 Thoroughbred yearlings for 6 months using a conventional yearling race training programme. They were then detrained for 10 weeks with free range on pasture for 8 h/day and stall rest at night. Treadmill measurements of O2 transport variables were made before training (PRE), after training (TR) and after detraining (DT). A step-test protocol identified each horse's aerobic capacity (VO2max) and speed to attain it, and a steady-state run at VO2max was used to quantify 02 transport variables at each time period.

RESULTS

The mass-specific and whole-body VO2max, cardiac output (Q) and stroke volume (Vs) increased from PRE to TR. All mass-specific values decreased significantly from TR to DT; however, because body mass increased by 8.3% from TR to DT, none of the variables changed significantly from TR to DT on a whole-body basis.

CONCLUSIONS

Changes in aerobic capacity are highly correlated with changes in Vs and circulatory capacity during training and detraining. Exercise activity of trained young horses free at pasture for 8 h/day is sufficient to maintain VO2max, (Q and Vs during 10 weeks of DT.

POTENTIAL RELEVANCE

Aerobic and cardiovascular fitness may be maintained in young Thoroughbred horses during at least 10 weeks of detraining by maintaining modest spontaneous exercise activity.

Recruitment pattern of muscle fibre type during flat and sloped treadmill running in thoroughbred horses

REASONS FOR PERFORMING THE STUDY

There is little information about the muscle fibre recruitment pattern during sloped and flat track running in Thoroughbred horses.

OBJECTIVES

To examine the glycogen depletion pattern of each muscle fibre type during running on a flat and sloped treadmill.

METHODS

Thirteen Thoroughbred horses (3-9 years old) were used. They were initially subjected to incremental exercise tests on a treadmill at 10 and 0% inclines in each horse to determine running speed at 90 and 60% VO2max. Needle biopsy samples were obtained from the middle gluteal muscle immediately after the running at 90% VO2max for 4 min and 60% VO2max for 12 min on 10% and 0% inclines treadmill. Four muscle fibre types (Types I, IIA, IIA/IIX, and IIX) were immunohistochemically identified, and optical density of Periodic Acid Schiff staining (OD-PAS) in each fibre type and the glycogen content of the muscle sample were determined by quantitative histochemical and biochemical procedures.

RESULTS

The changes in OD-PAS showed that the recruitment of all fibre types were identical after each exercise bout, i.e., 4 min running at 90% VO2max (8.4-9.4 m/sec on 10%, 13.9-14.1 m/sec on 0%), and 12 min running at 60% VO2max (5.4-6.0 m/sec on 10%, 7.9-11.2 m/sec on 0%). No significant differences were found in the recruitment patterns of each muscle fibre type between 10 and 0% inclined exercise bouts at the same exercise intensity.

CONCLUSIONS

The recruitment pattern of muscle fibre type is mainly determined by exercise intensity (%VO2max) and duration, but not by running speed.

POTENTIAL RELEVANCE

The results of this study indicate the possibility that up-hill running results in the same training effect as faster running on a flat track.

Recruitment pattern of muscle fibre type during high intensity exercise (60–100% VO2max) in Thoroughbred horses

To consider the optimal training programme for Thoroughbred horses, we examined the recruitment pattern of muscle fibres including hybrid muscle fibres in well-trained Thoroughbred horses. The horses performed exercise at three different intensities and durations; i.e., 100% VO2max for 4 min, 80% and 60% VO2max for 8 min on a treadmill with 10% incline. Muscle samples were obtained from the middle gluteal muscle before, during (4 min at 80% and 60% VO2max), and after exercise. Four muscle fibre types (types I, IIA, IIA/IIX, and IIX) were immunohistochemically identified, and optical density of periodic acid Schiff staining (OD-PAS) in each fibre type, and the glycogen content of the muscle sample, were determined by quantitative histochemical and biochemical procedures. The changes in OD-PAS showed that the recruitment of all fibre types were identical at the final time stage of each exercise bout, i.e., 4 min running at 100% VO2max, and 8 min running at 80% and 60% VO2max. The changes in OD-PAS of type IIA/IIX fibre were very similar to those of type IIX fibre. The recruitment of these fibres were obviously more facilitated by 4 min running at 100% VO2max than by 4 min running at 80% or 60% VO2max. Short duration with high intensity exercise, such as 4 min running at 100% VO2max or 8 min running at 80% or 60% VO2max, is effective to stimulate type IIX fibre and IIA/IIX fibres that have the fastest speed of contraction.

Effect of high intensity training on anaerobic capacity of middle gluteal muscle in Thoroughbred horses

We hypothesize that high intensity training for Thoroughbred horses that have been subjected to conventional training could further improve the metabolic properties of the middle gluteal muscle. Nine well-trained horses were subjected to high intensity (80-100% Vdot;O(2)max, 5 minx2) training for 12 weeks. Biopsy samples were obtained from the muscle before and after 4 and 12 weeks of training. Three of the 9 horses did not complete the training programme. In the remaining 6 horses, activities of succinic dehydrogenase (SDH), phosphofructokinase (PFK) and 3-hydroxy acyl CoA dehydrogenase (HAD), and the composition of myosin heavy chain isoforms were analyzed by biochemical techniques. After 12 weeks of training, a significant increase was found in PFK activity but not in the SDH and HAD activities. There were no significant changes in the composition of myosin heavy chain isoforms. The high intensity training in this study was effective at increasing glycolytic enzyme activity, indicating the possibility to improve anaerobic capacity, which potentially could contribute greatly to performance in Thoroughbred horses. This study also highlighted a fact that high intensity training should be given with the great care to prevent the skeletal muscle injuries.

Biomechanical implications of uphill training on the aetiology of tendinitis

It has been reported that a small decrease in the strain in the superficial digital flexor tendon (SDFT) occurs if the toe is raised during walking. Although walking on a slope appears similar to raising the toe, it is unclear whether uphill exercise decreases the strain in the SDFT. Because the force or strain on tendons is one of the important factors leading to tendon stress injury, we hypothesised that reducing the force in the SDFT during exercise may prevent tendinitis. The purpose of this study was to determine the effects of treadmill inclination on the force in the SDFT in the walking horse. 'Arthroscopically implantable force probes' (AIFP) were implanted into the SDFT of the forelimb of 4 horses. The AIFP output was recorded during walking on a treadmill inclined at 0%, 3%, 8% and then 0% again. When the inclination increased from 0 to 8%, the first peak of force in the SDFT decreased significantly, the second increased significantly, but the maximal force and the area under the force-time curve did not change. In conclusion, uphill walking on an inclined treadmill did not decrease the maximal force in the SDFT or the area under the force-time curve, however, the patterns of force were altered. Future research should focus on the force distributions of tendons and ligaments at faster gaits, because the effects of a change in hoof angle and slope may be greater at faster gaits.

Bronchoalveolar lavage for the diagnosis and treatment of pneumonia associated with transport in Thoroughbred racehorses

To evaluate a hypothese that use of bronchoalveolar lavage (BAL) for early treatment of pneumonia would improve their prognosis by reducing bacterial numbers and excessive numbers of neutrophils in the lung, initial experiences with BAL in the diagnosis and treatment of pneumonia were performed in 36 racehorses that became ill within 24 hr of long distance travel (1,200-1,600 km, 26-32 hr) by road. Comparisons were made of the outcomes of the 36 horses and those of 42 horses (81.0% recovered, 50.0% returned to racing) treated for transport associated pneumonia without BAL. The total amount of BAL fluid injected during hospitalization varied from 700 to 3,700 ml and the duration of antibiotic treatments ranged from 5 to 40 days. Clinical symptoms after lavages showed good results with no side effects. None of the horses required thoracic drainage. Horses treated with BAL required shorter period of antibiotic therapy, a greater percentage recovered (100%, 36/36) and a greater percentage returned to racing (77.8%, 28/36). Eight (22.2%) never raced because of lameness or other considerations.

Evasion of host defenses by measles virus: wild-type measles virus infection interferes with induction of Alpha/Beta interferon production

Measles is a highly contagious disease currently responsible for over one million childhood deaths, particularly in the developing world. Since alpha/beta interferons (IFNs) are pivotal players both in nonspecific antiviral immunity and in specific cellular responses, their induction or suppression by measles virus (MV) could influence the outcome of a viral infection. In this study we compare the IFN induction and sensitivity of laboratory-passaged attenuated MV strains Edmonston and Moraten with those of recent wild-type viruses isolated and passaged solely on human peripheral blood mononuclear cells (PBMC) or on the B958 marmoset B-cell line. We report that two PBMC-grown wild-type measles isolates and two B958-grown strains of MV induce 10- to 80-fold-lower production of IFN by phytohemagglutinin-stimulated peripheral blood lymphocytes (PBL) compared to Edmonston and Moraten strains of measles. Preinfection of PBL with these non-IFN-inducing MV isolates prevents Edmonston-induced but not double-stranded-RNA-induced IFN production. This suggests that the wild-type viruses can actively inhibit Edmonston-induced IFN synthesis and that this is not occurring by double-stranded RNA. Furthermore, the wild-type MV is more sensitive than Edmonston MV to the effect of IFN. MV is thus able to suppress the synthesis of the earliest mediator of antiviral immunity, IFN-alpha/beta. This could have important implications in the virulence and spread of MV.

CD40 ligand-mediated interactions are involved in the generation of memory CD8(+) cytotoxic T lymphocytes (CTL) but are not required for the maintenance of CTL memory following virus infection

CD8(+) cytotoxic T lymphocytes (CTL) play a key role in the control of many virus infections, and the need for vaccines to elicit strong CD8(+) T-cell responses in order to provide optimal protection in such infections is increasingly apparent. However, the mechanisms involved in the induction and maintenance of CD8(+) CTL memory are currently poorly understood. In this study, we investigated the involvement of CD40 ligand (CD40L)-mediated interactions in these processes by analyzing the memory CTL response of CD40L-deficient mice following infection with lymphocytic choriomeningitis virus (LCMV). The maintenance of memory CD8(+) CTL precursors (CTLp) at stable frequencies over time was not impaired in CD40L-deficient mice. By contrast, the initial generation of memory CTLp was affected. CD40L-deficient mice produced lower levels of CD8(+) CTLp during the primary immune response to LCMV than did wild-type controls, despite the fact that the LCMV-specific effector CTL response of CD40L-deficient mice was indistinguishable from that of control animals. The differentiation of naïve CD8(+) T cells into effector and memory CTL thus involves pathways that can be discriminated from each other by their requirement for CD40L-mediated interactions. Expression of CD40L by CTLp themselves was not an essential step during their expansion and differentiation from naïve CD8(+) cells into memory CTLp; instead, the reduction in memory CTLp generation in CD40L-deficient mice was likely a consequence of defects in the CD4(+) T-cell response mounted by these animals. These results thus suggest a previously unappreciated role for CD40L in the generation of CD8(+) memory CTLp, the probable nature of which is discussed.