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Augusto Pocobelli,1 Chiara Komaiha,1 Luca De Carlo,1 Giulio Pocobelli,2 Nicoletta Boni,1 Rossella Anna Maria Colabelli Gisoldi1 1San Giovanni Addolorata Hospital, UOC Oftalmologia – Banca degli occhi, Rome, Italy; 2Department of Experimental Medicine and Surgery, University of Rome Tor Vergata, Ophthalmology Unit, Rome, ItalyCorrespondence: Chiara KomaihaSan Giovanni Addolorata Hospital, UOC Oftalmologia – Banca degli occhi, Via Santo Stefano Rotondo, 6, Rome 00184, ItalyTel +39-0677052950Email ckomaiha@hsangiovanni.roma.itBackground: NK is one of the most challenging ocular conditions to treat and it can represent a devastating complication of acoustic neuroma surgery due to the profound corneal anesthesia and concomitant exposure keratopathy caused by seventh nerve palsy. In such cases, cornea surgery should be considered with extreme caution due to the high risk of devastating complications. The purpose of the study is to report the efficacy of a novel human recombinant nerve growth factor (rhNGF)-based ophthalmic treatment in a functionally monocular patient with a recurrence of severe neurotrophic keratitis (NK) on a corneal graft.Case Presentation: A 24-year-old woman who underwent acoustic neuroma surgery was referred for the assessment of a lagophthalmos and a paracentral corneal ulcer refractory to medical treatment. The patient presented with a large descemetocele, diagnosed as stage 3 NK that required multilayer amniotic membrane transplantation (AMT) and a following optical penetrating keratoplasty (PK). The recurrence of NK on the graft was successfully treated with a cycle of rhNGF (cenegermin 20 μg/mL) eye drops. Due to the complications of a further NK recurrence after treatment discontinuation, a second AMT and PK approach was chosen. A second cycle of treatment with cenegermin was immediately initiated after PK to prevent further recurrences. No postoperative complications were observed and we report a stable situation at 1 year of follow-up.Conclusion: The case presented here is, to our knowledge, the first report of a treatment with cenegermin for a NK recurrence after PK and suggests that such early medical approach could be evaluated to prevent postoperative complications.Keywords: neurotrophic keratitis, nerve growth factor, acoustic neuroma, cornea transplant, cenegermin

Investigates the effect of the multiple administration of histamine antagonist tripelennamine (TP) on the disposition of antipyrine (AP) in camels. Plasma concentration of TP and AP; Pharmacokinetic parameters of AP; Drug-drug interactions.

The pharmacokinetics of tripelennamine (T) was compared in horses (n=6) and camels (n=5) following intravenous (i.v.) administration of a dose of 0.5 mg/kg body weight. Furthermore, the metabolism and urinary detection time was studied in camels. The data obtained (median and range in brackets) in camels and horses, respectively, were as follows: the terminal elimination half-lives were 2.39 (1.91–6.54) and 2.08 (1.31–5.65) h, total body clearances were 0.97 (0.82–1.42) and 0.84 (0.64–1.17) L/h/kg. The volumes of distribution at steady state were 2.87 (1.59–6.67) and 1.69 (1.18–3.50) L/kg, the volumes of the central compartment of the two compartment pharmacokinetic model were 1.75 (0.68–2.27) and 1.06 (0.91–2.20) L/kg. There was no significant difference (Mann–Whitney) in any parameter between camels and horses. The extent of protein binding (mean±SEM) 73.6±8.5 and 83.4±3.6% for horses and camels, respectively, was not significantly statistically different (t-test). Three metabolites of T were identified in urine samples of camels. The first one resulted from N-depyridination of T, with a molecular ion of m/z 178, and was exclusively eliminated in conjugate form. This metabolite was not detected after 6 h of T administration. The second metabolite, resulted from pyridine ring hydroxylation, had a molecular ion of m/z 271, and was also exclusively eliminated in conjugate form. This metabolite could be detected in urine sample for up to 12 h after T administration. The third metabolite has a suspected molecular ion of m/z 285, was eliminated exclusively in conjugate form and could be detected for up to 24 h following T administration. T itself could be detected for up to 27 h after i.v. administration, with about 90% of eliminated T being in the conjugated form. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to evaluate the role of a polyethylene glycol 400 - propylene glycol - hydroxypropyl guar - hyaluronic acid eye drops in relieving the symptoms of dry eye syndrome after anti-VEGF intravitreal injection., Methods: In this randomized, parallel-group study, patients were randomized to receive standard therapy alone or study eye drops plus standard therapy. Patients enrolled were older than 50 with exudative age-related macular degeneration, who have never had intravitreal injections, and without severe dry eye condition or severe ocular or systemic conditions. Patients had baseline preoperative evaluation (V0), and successively after 15 (V1) and 30 (V2) days. At VO and V1 T-BUT, Schirmer's test, fluorescein staining, DEQ5 and OSDI questionnaires were performed and at V2 (30) the OSDI questionnaire was administered., Results: 80 patients were included in the study, of them 40 received standard therapy plus study eye drops. DEQ5 questionnaire showed an increase in the control group between the values at V0 and V1, while in the study group a decrease was observed. No changes in T-BUT, Schirmer, and fluorescein staining values between V0 and V1 were observed in both groups. OSDI data in the control group showed no statistically significant differences, while in the study group they showed a statistically significant difference., Conclusions: In our study patients undergoing for the first time intravitreal treatment presented dry eye symptoms in the postoperative period: in this group of patients the use of a tears substitute reduces postoperative ocular discomfort., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Purpose: The primary objective of this study is to evaluate the efficacy and safety profile of PreserFlo MicroShunt implantation in the medium- to long-term follow-up of patients with open-angle glaucoma. The secondary objective is to analyze laser flare meter (LFM) values before and after PreserFlo MicroShunt implantation., Methods: This prospective, observational, longitudinal single-center study included a total of 62 eyes from 54 patients. A subgroup of 27 eyes (26 patients) reached the 12-month follow-up. Success was defined based on three criteria: criterion A: IOP ≤21 mmHg and ≥20% reduction; criterion B: IOP ≤15 mmHg and ≥25% reduction; and criterion C: IOP ≤12 mmHg and ≥30% reduction. Success was further categorized as complete if achieved without IOP-lowering medications and qualified if achieved with medication administration. Other aspects evaluated included the number of IOP-lowering medications (baseline and postoperative), development of postoperative complications, 5-FU injections or implant revision, and LFM values., Results: The 12-month follow-up group (27 patients) was composed by 50% males and had a mean age of 75.54 ± 9.98 years. Success rates at 12 months were as follows: 78% for criterion A, 56% for criterion B, and 26% for criterion C. Complete success, as defined by criterion A, was achieved by 67% of the patients, 29% achieved qualified success, and one eye (4%) experienced failure. IOP decreased from 25.26 ± 1.67 mmHg at baseline to 14.81 ± 0.74 mmHg at 12 months. The number of medications decreased from 3.67 ± 1.30 at baseline to 0.48 ± 0.75 at 12 months. Reported complications were choroidal detachment (11%), hyphema (5%), and athalamia (flat anterior chamber) (2%) 13 eyes (48%) received 5-FU injections, while 7 eyes (26%) underwent implant revision. No significant increase in LFM values was observed. Eyes with a regular postoperative course and IOP ≤15 mmHg showed significantly lower LFM values than patients with unfavorable outcomes (IOP >15 mmHg, development of complications, 5-FU injection, or implant revision)., Conclusions: PreserFlo MicroShunt showed a significant reduction in IOP and a decrease in the number of IOP-lowering medications. Complications occurred at a modest frequency. The implant provides a minimally invasive approach with no significant increases in LFM values postoperatively. Higher LFM values correlate with unfavorable postoperative outcomes., Competing Interests: The authors declare that there are no conflicts of interest., (Copyright © 2024 Carlo Cagini et al.)

In the developing human brain, only 53 stochastically expressed clustered protocadherin (cPcdh) isoforms enable neurites from individual neurons to recognize and self-avoid while simultaneously maintaining contact with neurites from other neurons. Cell assays have demonstrated that self-recognition occurs only when all cPcdh isoforms perfectly match across the cell boundary, with a single mismatch in the cPcdh expression profile interfering with recognition. It remains unclear, however, how a single mismatched isoform between neighboring cells is sufficient to block erroneous recognitions. Using systematic cell aggregation experiments, we show that abolishing cPcdh interactions on the same membrane ( cis ) results in a complete loss of specific combinatorial binding between cells ( trans ). Our computer simulations demonstrate that the organization of cPcdh in linear array oligomers, composed of cis and trans interactions, enhances self-recognition by increasing the concentration and stability of cPcdh trans complexes between the homotypic membranes. Importantly, we show that the presence of mismatched isoforms between cells drastically diminishes the concentration and stability of the trans complexes. Overall, we provide an explanation for the role of the cPcdh assembly arrangements in neuronal self/non-self-discrimination underlying neuronal self-avoidance., Competing Interests: Competing interests statement:The authors declare no competing interest.

Chloroethenes are globally prevalent groundwater contaminants. Since 2014, TCE has been shown to be degradable in an aerobic metabolic process where it is used as sole energy source and growth substrate by a mixed bacteria culture (SF culture). In 2019, the SF culture was shown to be successfully used in bioaugmentation approaches under field-relevant conditions. In this study, a combined bio-/electro-approach to stimulate the TCE degradation by the SF culture was investigated in laboratory experiments. Column experiments were set up to compare a bioaugmentation approach with an electrochemical biostimulated bioaugmentation approach. Low strength direct current increased the amount of degraded TCE to about 150 % of the control. Through lowering the inflow concentration of oxygen, the effect of the electro-biostimulation in a low oxygen setting confirmed the potential of the bio-electro process for treatment of oxygen-deprived, TCE-contaminated sites., (© 2023. The Author(s).)

Crystal structures of many cell-cell adhesion receptors reveal the formation of linear "molecular zippers" comprising an ordered one-dimensional array of proteins that form both intercellular ( trans ) and intracellular ( cis ) interactions. The clustered protocadherins (cPcdhs) provide an exemplar of this phenomenon and use it as a basis of barcoding of vertebrate neurons. Here, we report both Metropolis and kinetic Monte Carlo simulations of cPcdh zipper formation using simplified models of cPcdhs that nevertheless capture essential features of their three-dimensional structure. The simulations reveal that the formation of long zippers is an implicit feature of cPcdh structure and is driven by their cis and trans interactions that have been quantitatively characterized in previous work. Moreover, in agreement with cryo-electron tomography studies, the zippers are found to organize into two-dimensional arrays even in the absence of attractive interactions between individual zippers. Our results suggest that the formation of ordered two-dimensional arrays of linear zippers of adhesion proteins is a common feature of cell-cell interfaces. From the perspective of simulations, they demonstrate the importance of a realistic depiction of adhesion protein structure and interactions if important biological phenomena are to be properly captured.

Purpose: To study the features of corneal confocal microscopy of eyes with Fuchs' endothelial corneal dystrophy (FECD) after successful Descemet stripping automated endothelial keratoplasty (DSAEK) versus Descemet membrane endothelial keratoplasty (DMEK)., Methods: Thirty-two eyes affected by FECD with corneal oedema requiring a corneal graft were treated with DSAEK (15 eyes) or DMEK (17 eyes). All patients underwent in vivo corneal confocal microscopy (IVCCM) at 6 months postoperatively. We evaluated preoperative and postoperative corrected distance visual acuity (CDVA) and the correlation with IVCCM characteristics., Results: Using IVCCM, Z-scan curve analysis showed similar subepithelial reflectivity peaks between the two groups (DSAEK 1256 SU ± 514 vs DMEK 1118 SU ± 408, p  = 0.411), while the interface reflectivity was significantly higher in the DMEK group (1511 SU ± 357) than in the DSAEK group (1029 SU ± 413, p  = 0.002)., Conclusion: Comparing the corneal confocal microscopic characteristics after DMEK with those after DSAEK and their correlation with visual outcome at 6 months, we hypothesized that the presence of a third reflectivity peak in the Z-scan curves of DSAEK patients could justify the poorer visual outcome with this endothelial surgery than with DMEK.

Although there is increasing concern about both the prevalence of, and harms associated with the abuse of older adults, progress in the development of interventions to prevent its occurrence has been slow. This paper reports the findings of a systematic review of the published literature that identified studies in which the outcomes of preventative interventions are described. A total of eight different intervention trials, published since 2004, are described across the primary, secondary and tertiary levels of prevention and in terms of the types of risk factor that they target. The current evidence to support the effectiveness of these interventions is not only limited by the small number of outcome studies but also the poor quality of evaluation designs and the focus of many interventions on single risk factors. It is concluded that work is needed to strengthen the evidence base that supports the delivery of interventions to prevent elder abuse., (© 2016 John Wiley & Sons Ltd.)

Electrostatically actuated torsional micromirrors are key elements in Micro-Opto-Electro- Mechanical-Systems. When forced by means of in-plane comb-fingers, the dynamics of the main torsional response is known to be strongly non-linear and governed by parametric resonance. Here, in order to also trace unstable branches of the mirror response, we implement a simplified continuation method with arc-length control and propose an innovative technique based on Finite Elements and the concepts of material derivative in order to compute the electrostatic stiffness; i.e., the derivative of the torque with respect to the torsional angle, as required by the continuation approach.

Unlabelled: The impact of arrhythmias on the evaluation of perfusion data from myocardial gated SPECT has been assessed by comparing arrhythmic patients with nonarrhythmic patients or by simulating rhythm disturbances. Whether gating-related artifacts may have a clinically relevant influence on the evaluation of perfusion in atrial fibrillation (AF) patients is still uncertain. Recently, collection of nongated and gated datasets during the same SPECT acquisition has become possible. The aim of this study was to examine the difference in myocardial perfusion between simultaneously acquired gated and nongated SPECT data in AF patients., Methods: In 44 consecutive AF patients who underwent myocardial perfusion SPECT for standard clinical indications, both a gated and a nongated study were simultaneously acquired. Perfusion was estimated in a masked manner on a 20-segment model using an established scoring scheme., Results: Agreement was good between the gated and nongated perfusion scores on a segment basis; the agreement for resting scores was the highest, with those for stress and difference scores being lower (Spearman rho = 0.82, 0.74, and 0.55, respectively). On a patient basis, a similar trend was seen in summed resting scores (rho = 0.911), summed stress scores (rho = 0.779), and summed difference scores (rho = 0.596). When summed stress and summed difference data were grouped by severity class (normal, mild abnormality, moderate abnormality, and severe abnormality), agreement decreased from rho = 0.818, kappa = 0.639, for summed stress score to rho = 0.549, kappa = 0.367, for summed difference score. The severity class of inducible ischemia changed in 17 patients (39%) if a (summed) gated image was used instead of a standard nongated perfusion image., Conclusion: AF may have a clinically relevant impact on summed gated perfusion images, compared with images simultaneously obtained without gating in the same patients. Therefore, acquisition of a nongated SPECT study is mandatory for accurate assessment of myocardial perfusion in AF patients.

The success of external cardioversion (ECV) of atrial fibrillation depends on generating sufficient transmyocardial current for defibrillation with minimal myocardial injury. Thoracic electrical impedance plays an important role in the relation between the delivered energy and transmyocardial current. This study assessed the determinants of thoracic electrical impedance in ECV of atrial fibrillation. ECV of atrial fibrillation was performed in 80 consecutive patients (mean age 73 +/- 9 years; men 69%; body mass index 26.0 +/- 3.6 kg/m(2)) within 12 months, using biphasic shocks (Multipulse Biowave) delivered through adhesive pads in an anteroposterior position. Thoracic electrical impedance was measured using the first shock. The mean thoracic electrical impedance was 57.7 +/- 12.3 Omega (energy 71 +/- 43 J, current intensity 33 +/- 12 A). Sinus rhythm was immediately restored in 75 patients (94%). Thoracic electrical impedance was greater (60.9 +/- 11.8 vs 51.7 +/- 11.0 Omega, p = 0.001) in patients requiring >1 shock (65%). At multivariate linear regression analysis (R = 0.761, p <0.001), female gender (+9.7 +/- 2.0 Omega, p <0.001), body mass index (+1.5 +/- 0.3 for a 1 kg/m(2) increase, p <0.001), hemoglobin concentration (+1.9 +/- 0.6 for a 1 g/dl increase, p = 0.004), and the presence of chronic heart failure (-5.3 +/- 2.0 Omega, p = 0.009) were independent predictors of thoracic electrical impedance. In conclusion, to increase ECV efficacy and minimize complications, the delivered energy should be adjusted in accordance with the clinical variables that independently affect thoracic electrical impedance and, hence, transmyocardial current.

The pharmacokinetics of caffeine were determined in 10 camels after an intravenous dose of 2.35 mg kg(-1). The data obtained (median and range) were as follows. The elimination half-life (t(1/2)) was 31.4 (21.2 to 58.9) hours, the steady state volume of distribution (V(SS)) was 0.62 (0.51 to 0.74) litre kg(-1)and the total body clearance (Cl(T)) was 14.7 (8.70 to 19.7) ml kg(-1)per hour. Renal clearance estimated in two camels was 0.62 and 0.34 ml kg(-1)per hour. In vitro plasma protein binding (mean +/-SEM, n = 10) to a concentration of 2 and 8 microg ml(-1)was 36.0 +/- 0.24 and 39.2 +/- 0.36 per cent respectively. Theophylline and theobromine were identified as caffeine metabolites in serum and urine. The terminal elimination half-life of the former, estimated in two camels, was 70. 4 and 124.4 hours. Caffeine could be detected in the urine for 14 days.

The pharmacokinetics of theophylline were determined after an intravenous (i.v.) dose of 2.36 mg/kg in six camels and 4.72 mg/kg body weight in three camels. The data obtained (median and range) for the low and high dose, respectively, were as follows: the distribution half-lives (t1/2 alpha) were 1.37 (0.64-3.25) and 2.66 (0.83-3.5) h, the elimination half-lives (t1/2 beta) were 11.8 (8.25-14.9) and 10.4 (10.0-13.5) h, the steady state volumes of distribution (Vss) were 0.88 (0.62-1.54) and 0.76 (0.63-0.76) L/kg, volumes of the central compartment (Vc) were 0.41 (0.35-0.63) and 0.51 (0.36-0.52) L/kg, total body clearances (Clt) were 62.3 (39.4-97.0) and 50.2 (47.7-67.4) mL/h.kg body weight and renal clearance (Vr) for the low dose was 0.6 (0.42-0.96) mL/h.kg body weight. There was no significant difference in the pharmacokinetic parameters between the two doses. Theophylline protein binding at a concentration of 5 micrograms/mL was 32.2 +/- 3.3%. Caffeine was identified as a theophylline metabolite but its concentration in serum and urine was small. Based on the pharmacokinetic values obtained in this study, a dosage of 7.5 mg/kg body weight administered by i.v. injection at 12 h intervals can be recommended. This dosing regimen should achieve an average steady state serum concentration of 10 micrograms/mL with peak serum concentration not exceeding 15 micrograms/mL.

The pharmacokinetics of promethazine were determined in seven camels (Camelus dromedarius) after an intravenous dose of 0.5 mg kg body weight.-1 The data obtained (median and range) were as follows: the elimination half-life (t1/2 beta) was 5.62 (2.84-6.51) h; the steady state volume of distribution (Vdss) was 8.90 (7.10-12.00) L kg-1, total body clearance (CT) was 24.5 (17.22-33.65) ml kg-1 min-1 and renal clearance (Clr) was 4.81 (1.97-5.48) ml kg-1 min-1., (Copyright 1999 W.B. Saunders Company Ltd.)

Objective: To document tolfenamic acid disposition variables, identify its major phase-1 metabolite and fragmentation pattern, and establish detection time in urine after single IV bolus administration to make recommendations on avoiding violative residues in racing camels., Animals: 7 healthy camels (6 males, 1 female), 8 to 11 years old and weighing from 300 to 480 kg., Procedure: Blood samples were collected at 0, 5, 10, 15, 30, 45, and 60 minutes and at 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 8, 12, 13, 14, 15, and 16 hours after IV administration of tolfenamic acid (2.0 mg/kg of body weight). Urine samples were collected daily for 14 days after drug administration. Serum tolfenamic acid concentration was measured; limit of quantification was 50 ng/ml. A metabolite of tolfenamic acid in urine was isolated and identified, and its major fragmentation pattern was verified. Screening for tolfenamic acid and its metabolite in urine was performed., Results: Mean +/- SEM tolfenamic acid elimination half-life was 5.76+/-0.26 hours. Total body clearance was 0.109+/-0.011 L/kg/h, and steady-state volume of distribution was 0.68+/-0.06 L/kg. Detection time for tolfenamic acid and its hydroxylated metabolite in urine after IV administration of a dose of 2.0 mg/kg was 5 and 7 days, respectively., Conclusions: Camels eliminate tolfenamic acid mainly via metabolism more slowly than do cattle. The extrapolated dose regimen from cattle to camels appears inappropriate. Veterinarians are advised not to use tolfenamic acid in camels for at least 8 days prior to racing.

The pharmacokinetics of flunixin were determined after an intravenous dose of 1.1 mg/kg body weight in six camels and 2.2 mg/kg body weight in four camels. The data obtained (mean +/- SEM) for the low and high dose, respectively, were as follows: The elimination half-lives (t1/2 beta) were 3.76 +/- 0.24 and 4.08 +/- 0.49 h, the steady state volumes of distribution (Vdss) were 320.61 +/- 38.53 and 348.84 +/- 35.36 mL/kg body weight, total body clearances (ClT) were 88.96 +/- 6.63 and 84.86 +/- 4.95 mL/h/kg body weight and renal clearances (Clr) were 0.52 +/- 0.09 and 0.62 +/- 0.18 mL/h/kg body weight. A hydroxylated metabolite of flunixin was identified by gas chromatography/mass spectrometry (GC/MS) under electron and chemical ionization and its major fragmentation pattern was verified by tandem mass spectrometry (GC/MS/MS) using neutral loss, daughter and parent scan modes. The detection times for flunixin and its hydroxylated metabolite in urine after an intravenous (i.v.) dose of 2.2 mg/kg body weight were 96 and 48 h, respectively.

A flunixin metabolite, a hydroxylated product, has been identified in camel urine and plasma samples using gas chromatography-mass spectrometry (GC-MS) and GC-MS-MS in the electron impact and chemical ionization modes. Its major fragmentation pattern has been verified by GC-MS-MS in daughter ion and parent ion scan modes. The method could detect flunixin and its metabolite in camel urine after a single intravenous dose of 2.2 mg of flunixin/kg body weight for 96 and 48 h, respectively, which increases the reliability of antidoping control analysis.

The activity of hepatic mixed function oxidases was compared in horses and camels (Camelus dromedarius) by studying the pharmacokinetics of antipyrine in seven camels and five horses following intravenous administration of a single dose of antipyrine (25 mg/kg). The data obtained (mean +/- SEM and median in brackets) in camels and horses, respectively, were as follows: the elimination half-lives were 3.25 +/- 0.23 (3.19) and 3.09 +/- 0.25 (2.90) hr; the apparent volumes of distribution (area method) were 0.691 +/- 0.045 (0.648) and 0.642 +/- 0.034 (0.676) l/kg; the volumes of distribution at steady state were 0.659 +/- 0.040 (0.607) and 0.620 +/- 0.030 (0.653) l/kg; the volume of the central compartment of the two-compartment pharmacokinetic model were 0.386 +/- 0.0523 (0.349) and 0.298 +/- 0.05 (0.308) l/kg; total body clearances were 0.148 +/- 0.008 (0.158) and 0.145 +/- 0.007 (0.147) l/kg/hr; the areas under the curves to infinity were 171.0 +/- 9 (165) and 175 +/- 8.0 (170) micrograms.ml.hr. There was no statistical significance in any parameter between camels and horses which suggests that the activity of hepatic mixed function oxidases is similar in horses and camels.

Objective: To document disposition variables of phenylbutazone and its metabolite, oxyphenbutazone, in camels (Camelus dromedarius) after single i.v. bolus administration of phenylbutazone, with a view to making recommendation on avoiding violative residues in racing camels., Animals: 6 healthy camels (4 males, 2 females), 5 to 7 years old, and weighing from 350 to 450 kg., Procedure: Blood samples were collected to 0, 5, 10, 15, 45, and 60 minutes and at 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 8, 12, 24, 26, 28, 30, 40, 48, 50, 53, and 60 hours after i.v. administration of 4.5 mg of phenylbutazone per kg of body weight. Urine was obtained in fractions during the entire blood sample collection period. Serum and urine phenylbutazone concentrations were measured by high-performance liquid chromatography; assay sensitivity was 100 ng/ml. Serum oxyphenbutazone concentration was measured by gas chromatography/mass spectrometry; assay sensitivity was 10 ng/ml., Results: Disposition of phenylbutazone was best described by a two-compartment open model. Mean +/- SEM elimination half-life was 13.44 +/- 0.44 hours. Total body clearance was 12.63 +/- 1.64 mg/kg/h. Renal clearance was between 0.3 and 0.4% of total body clearance. The elimination half-life of oxyphenbutazone was 23.9 +/- 2.09 hours., Conclusions: The elimination half-life and total body clearance of phenylbutazone in camels are intermediate between reported values in horses and cattle. Extrapolation of a dosage regimen from either species to camels is, therefore, not appropriate. Elimination of phenylbutazone in camels is mainly via metabolism. Owing to the long half-life of phenylbutazone and of oxyphenbutazone, and to the zero drug concentration regulation adopted by the racing commissioner in the United Arab Emirates, practicing veterinarians would be advised not to use phenylbutazone in camels for at least 7 days prior to racing.