The bioavailability and nonlinear pharmacokinetics of MK-679 in humans

MK-679 (R(?)-3-((3-(2-(7-chloro-2-quinolinyl)ethenyl)phenyl)(3-(dimethylamino)-3-oxopropyl)thio)methyl)thio(propanoic acid) is a potent and specific LTD₄-receptor antagonist. The disposition of MK-679 was investigated in a three-way crossover study in 12 healthy males receiving single intravenous doses of 75, 250, and 500 mg of MK-679. A greater than proportional increase in the area under the plasma concentration—time curve of MK-679 was observed with increase in dose. The plasma concentration data for each subject fitted well to the differential equations for a two-compartment model with linear tissue distribution and Michaelis-Menten elimination from the central compartment, indicating that the elimination of MK-679 in humans is saturable. In a previous study, the disposition of MK-679 in humans was also dose-dependent when given together with its S(+)-isomer, L-668,018. Thus, the disposition of MK-679 in humans is dose-dependent regardless of the presence of its stereoisomer. Also, the bioavailability of MK-679 was determined in six healthy males receiving simultaneously an oral dose of 250 mg of MK-679 and intravenous infusion of 1 mg ¹⁴C-MK-679. Results of this study indicate that the oral bioavailability of MK-679 is nearly quantitative.     

Profile of etodolac: Pharmacokinetic evaluation in special populations

The pharmacokinetics of etodolac, a new nonsteroidal anti-inflammatory drug, were compared in normal subjects, in patients with renal and hepatic disease, and in elderly patients. In 28 normal subjects, orally administered etodolac was rapidly absorbed. By 1.2 hours after ingestion of a 200 mg dose, the maximum serum concentration (C_max) averaged 15.9 g/ml, with more than 99% of the drug bound to serum protein. Clearance was primarily hepatic. The mean half-life (t_1/2) was 6 to 7 hours. There were no apparent differences in C_max, the time at which C_max occurred (t_max), area under the serum concentration/time curve (AUC_0–24), or t_1/2 between groups of young men (n=20), elderly men (n=24), and elderly men with osteoarthritis (n=20), after a single dose of etodolac or after 7 days of subchronic administration. Moreover there was no evidence of accumulation. There also were no differences in C_max, t_max, AUC_0–24 or t_1/2 between groups of normal subjects (n=10) and patients with mild-to-moderate renal impairment (n=10). Patients with end-stage renal disease who were receiving chronic hemodialysis had the same mean serum concentration of free drug as normal subjects, even though mean serum levels of protein-bound etodolac were slightly lower than those in the normal subjects. The only significant (p<0.05) difference between patients with stable hepatic cirrhosis and normal, age-matched subjects was a slightly shorter t_max in the cirrhotic subjects (1.1 vs. 1.4 hours). These findings suggest that no alteration of etodolac dosage would be necessary in these high-risk groups.Die pharmakokinetischen Parameter von Etodolac, einem neuen, nichtsteroidalen entzündungshemmenden Therapeutikum, wurden an gesunden Probanden, an Patienten mit Leber- und Nierenleiden und an Älteren Patienten untersucht. Orale Etodolac Gaben wurden von den 28 gesunden Probanden schnell resorbiert. Nach einer einmaligen Dosis von 200 mg betrug nach 1,2 Stunden die durchschnittliche maximum Serumkonzentration (C_max) 15,9 g/ml, wobei mehr als 99% des Medikaments an das Serumprotein gebunden war. Clearance erfolgte hauptsÄchlich über die Niere. Die mittlere Eliminationshalbwertszeit (t_1/2) variierte zwischen 6 und 7 Stunden. In Bezug auf C_max, dem Zeitpunkt an dem C_max auftrat (t_max), FlÄche unter der Serumkonzentrationskurve (AUC_0–24) und t_1/2 wurden keine offensichtliche Unterschiede festgestellt zwischen der Gruppe junger MÄnnern (n=20), Älterer MÄnner (n=24) und Älteren MÄnnern mit Osteoarthritis (n=20) nach einer einmaligen Etodolac-Gabe oder nach 7 tÄgiger subchronischer Dosierung. Es bestanden auch keine Anzeichen einer Kumulation. ZusÄtzlich wurden auch keine Unterschiede in C_max, t_max, AUC_0–24 und t_1/2 zwischen der Gruppe gesunder Probanden (n=10) und der Patientengruppe mit leichten bis mÄigen NierenfunktionsschÄden (n=10) beobachtet. Im mittleren Serumspiegel des nicht gebundenen Medikaments in Patienten im Endstadium der Nierenerkrankung, die mit Langzeitdialyse behandelt wurden, konnte kein Unterschied im Vergleich zu gesunden Probanden festgestellt werden, obwohl der mittlere Serumspiegel für proteingebundenes Etodolac in den Patienten etwas niedriger lag als in gesunden Probanden. Der einzige signifikante Unterschied (p<0.05) zwischen Patienten mit stabilisierter Leberzirrhose und gleichaltrigen Probanden war eine etwas kürzere t_max in den Zirrhosepatienten (1,1 versus 1,4 Stunden). Diese Ergebnisse beweisen, dakeine Notwendigkeit vorliegt, die Etodolac-Dosierung für diese Risikogruppen zu modifizieren.Se comparó la farmacocinética de etodolac, un fármaco antiinflamatorio no esteroide nuevo, en sujetos normales y en pacientes con enfermedad renal y hepática y en pacientes ancianos. Etodolac administrado por vía oral a 28 sujetos normales fue rápidamente absorbido. A las 1,2 horas siguientes a la administración de una dosis de 200 mg, la concentración sérica máxima (C_max) alcanzó un promedio de 15,9 g/ml, con más del 99% del fármaco unido a la proteína sérica. La eliminación fue principalmente hepática. La vida media (t_1/2) fue 6–7 horas. No se observaron diferencias en C_max, en el tiempo en el cual se produjo C_max, en el área bajo la curva de concentración sérica/tiempo (ABC_0–24) ni en t_1/2 entre los grupos de hombres jóvenes (n=20), de hombres ancianos (n=24) y de hombres ancianos con osteoartritis (n=20), después de la administración de una dosis Única o después de 7 días de administración subcrónica de etodolac. Además, no hubo evidencia de acumulación. Tampoco se registraron diferencias en C_max, t_max, ABC_0–24 o t_1/2 entre los grupos de sujetos normales (n=10) y los pacientes con insuficiencia renal leve a moderada (n=10). Los pacientes con nefropatía terminal que estaban recibiendo hemodiálisis crónica tuvieron las mismas concentraciones séricas medias de fármaco libre que los sujetos normales, a pesar de que las concentraciones séricas medias de etodolac unido a proteina fueron levemente inferiores que en los sujetos normales. La Única diferencia significativa (p<0,05) entre los pacientes con cirrosis hepática estable y los sujetos normales de edad similar fue t_max ligeramente inferior en los sujetos cirróticos (1,1 vs 1,4 horas). Estos hallazgos sugieren que no es necesario modificar la dosis de etodolac para su uso en estos grupos de alto riesgo.La pharmacocinétique de l'étodolac, un anti-inflammatoire non stéroÏdien, a été comparé chez des sujets normaux et des patients présentant des affections rénales et hépatiques, et chez des malades âgés. Chez 28 sujets normaux, la résorption d'étodolac administré par voie orale a été rapide. Dès 1,2 heure suivant l'absorption d'une dose de 200 mg, la moyenne des concentration sériques maximales (C_max) était de 15,9 g/ml, plus de 99% pour cent du médicament étant liés aux protéines sériques. La clairance se fait surtout par voie hépatique. La demivie moyenne (t_1/2) était de 6 à 7 heures. Il n'y avait aucune différence apparente en ce qui concerne C_max, le temps d'apparition de C_max (t_max), l'aire sous la courbe concentration sérique/temps (AUC_0–24) ni t_1/2 entre les groupes d'hommes jeunes (n=20), d'hommes âgés (n=24), et d'hommes âgés atteints d'arthrose (n=20) à la suite d'une dose unique d'étodolac ou après 7 jours d'administration subchronique. De plus, aucune accumulation n'a été constatée. D'autre part, aucune différence de C_max, t_max, AUC_0–24 ni t_1/2 n'a été notée entre les groupes de sujets normaux (n=10) et de malades présentent des altérations rénales légères ou modérées (n=10). Les malades en insuffisance rénale terminale soumis à l'hémodialyse chronique ont présenté une concentration sérique moyenne de médicament libre analogue à celle des sujets normaux, mais la moyenne des taux sériques d'étodolac lié aux protéines était légèrement inférieure à celle observée chez les sujets normaux. La seule différence significative (p<0.05) entre les malades présentant une cirrhose hépatique stable et des sujets normaux appariés quant à l'âge était représentée par un t_max légèrement plus court chez les cirrhotiques (1,1 contre 1,4 heure). Ces données permettent de penser qu'aucune modification posologique de l'étodolac ne serait nécessaire pour ces groupes à haut risque.La farmacocinetica dell'etodolac, un nuovo farmaco anti-infiammatorio non steroidale è stata messa a confronto in gruppi normali, in pazienti affetti da malattia rénale ed epatica ed in pazienti anziani. In 28 soggetti normali l'etodolac somministrato oralmente è stato rapidamente assorbito. Dopo 1.2 ore dall'ingestione di una dose di 200 mg la massima concentrazione di siero (Cmax) presentava un valore medio di 15,9 mg/ml, con più del 99% del farmaco legato alla proteina del siero. La clearance era soprattutto a livello epatico. L'emivita media (t1/2) era di 6–7 ore. Non vi sono state evidenti differenze medie nei valori di concentrazione massima (Cmax), tempo (Tmax) al quale si aveva la Cmax, nella curva dell'area sotto concentrazione di siero/tempo (AUCo-24) oppure nel valore dell'emivita media (t1/2) tra gruppi di uomini giovani (n=20), uomini anziani (n=24) e anziani con osteoartrite (n=20), dopo una dose singola di etodolac o dopo 7 giorni di somministrazione subcronica. Inoltre non vi sono stati segni di accumulo. Per di più non vi sono state differenze nei valori di Cmax, tmax, AUCo-24 o t1/2 tra gruppi di soggetti normali (n=10) e pazienti con alterazioni renali da leggere a moderate (n=10). I pazienti con malattia renale all'ultimo stadio che ricevevano emodialisi cronica presentavano la stessa concentrazione media di siero di farmaco libero dei soggetti normali, anche se i livelli medi di siero di etodolac legato alle proteine erano leggermente inferiori a quelli di soggetti normali. L'unica differenza significativa (p<0.05) tra pazienti con cirrosi epatica stabile e soggetti normali della stessa età era nei tmax leggermente più brevi nei soggetti cirrotici (1.1. contro 1.4 ore). Questi risultati suggeriscono che nessuna alterazione del dosaggio di etodolac sarebbe necessaria in questi gruppi ad alto rischio.     

RENAL TRANSPLANTATION – AN EARLY EXPERIENCE

Renal transplant (RT) is now a therapy of choice for end stage renal disease (ESRD). The Nephrology Unit, Asvini started functioning in Dec 90 and to date 1298 sittings of hemodialysis have been given to 45 patients. Of these, 35 were in ESRD and 11 patients underwent renal transplantation at this hospital during the period Jan 91 – Dec 93. One patient expired after 18 months of transplantation due to infection. Early experience in screening patients for RT, use of immunosuppression, management of rejection episodes and protocol are presented with special emphasis on its relevance to the Armed Forces.KEY WORDS: Transplantation, Renal Failure, Immunosuppression, Rejection     

Pharmacokinetics of Nisoldipine Coat--Core Formulation in Subjects with Liver Cirrhosis

The pharmacokinetics of a controlled-release formulation (coat--core) of the calcium channel blocker nisoldipine was investigated in eight subjects with biopsy-proved liver cirrhosis and eight healthy subjects. In Stage I, subjects received a single 10-mg dose to determine if this dose would be safely tolerated in the subjects with cirrhosis. Because all subjects in both groups tolerated the dose without difficulty, all were continued to Stage II. In Stage II, subjects received a once-daily dose of 10-mg coat-core tablets for 7 days. Serial plasma samples were assayed for nisoldipine in both stages. The C(max) and AUC of nisoldipine were approximately fourfold to fivefold higher (p < 0.01) in subjects with cirrhosis as compared to healthy subjects; however, there was overlap in the range of pharmacokinetic parameters between the two groups. The accumulation factor following multiple dosing was similar in both groups. Results suggest that nisoldipine dose should be optimized by monitoring of a pharmacodynamic end point, such as effect on blood pressure. It is likely that dose requirements for patients with liver disease will be lower.     

HIV AND TUBERCULOSIS CO-INFECTION IN A REFERRAL CHEST HOSPITAL

Serving personnel of Armed Forces admitted with tuberculosis between Apr 1996–1999 were evaluated for co-infection of tuberculosis and HIV. Sixty (1.06%) of tuberculosis patients were found to be HIV positive. Initial test was done by spot kits and subsequently confirmed by ELISA on two different samples. Majority of the cases were in sexually active age group 48 (80%). Alcohol and smoking was associated in 80% cases. Thirty six (60%) were sputum smear positive for AFB. Twenty eight (46.7%) gave history of exposure to sex workers. Family members were not available for study. Sero prevalence of HIV in association with tuberculosis is less in Armed Forces compared to civil population.KEY WORDS: HIV, Seroprevalence, Tuberculosis     

Muramyl dipeptide: Not just another brick in the wall

The robust expression of microbial pattern recognition receptors such as TLR4 and Nod2 in intestinal stem cells reflects an active communication dynamic between the host and the gut microbiota. A new study reveals that muramyl dipeptide, the bacterial cell wall peptidoglycan motif, activates Nod2 within crypt base columnar Lgr5-positive stem cells and promotes their survival. Apart from the immediate relevance to the growth of organoids for in vitro experiments, the study raises new questions about the molecular mechanisms whereby gut microbes influence intestinal physiology.     

Safety and pharmacokinetics of multiple doses of aclidinium bromide administered twice daily in healthy volunteers

Chronic obstructive pulmonary disease (COPD) is characterized by progressive airway obstruction and increased cholinergic tone. The Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines recommend long-acting anticholinergics for COPD maintenance treatment. Aclidinium bromide is a novel, long-acting muscarinic antagonist developed for the treatment of COPD. A Phase I, randomized, single-blind, multiple-dose clinical trial was conducted to assess the safety and pharmacokinetics (PK) of multiple doses of twice-daily (BID) aclidinium in healthy subjects. Thirty healthy male and female subjects received aclidinium 200 μg, 400 μg, 800 μg, or placebo twice daily for 7 days. Subjects were randomized to 1 of 3 cohorts and 10 subjects in each cohort were randomized (8:2) to either aclidinium or placebo groups. Safety was assessed via adverse events (AEs), laboratory evaluations, vital signs, and ECGs. Plasma samples were obtained at multiple time points throughout the study and analyzed for aclidinium and its inactive acid and alcohol metabolites using a fully validated method of liquid chromatography coupled with tandem mass spectrometry. A total of 9 treatment-emergent AEs were reported (1, placebo; 3, aclidinium 400 μg; 5, aclidinium 800 μg), all of which were mild in severity. No serious AEs were reported. There were no clinically meaningful changes in laboratory parameters or vital signs. PK parameters on Day 7 following BID dosing of aclidinium showed that steady state was achieved for aclidinium and its metabolites. On Days 1 and 7, maximum plasma concentrations (C_max) of aclidinium were generally observed at the first PK time point (5 min postdose) and rapidly declined, with plasma concentrations generally less than 10% of C_max by 6 h postdose in all aclidinium groups. Mean effective t_½ after the evening dose on Day 7 ranged from 4.6 to 7.0 h for aclidinium 400 μg and 800 μg, similar to the terminal t_½ observed on Day 1 (4.5–5.9 h). Exposure for aclidinium and both metabolites increased with increasing dose, with the increase in exposure being less than dose proportional between the 400 μg and 800 μg doses. Overall, all doses of aclidinium were safe and well tolerated throughout the study. Pharmacokinetic steady state was reached for aclidinium and both metabolites within the 7-day treatment period for all doses tested. Aclidinium bromide exhibited time-independent PK following dosing to steady state, indicating that similar concentration versus time profiles will occur after repeated administration at the same dose and frequency.     

Contribution of a Mesocorticolimbic Subcircuit to Drug Context-Induced Reinstatement of Cocaine-Seeking Behavior in Rats

Cocaine-seeking behavior triggered by drug-paired environmental context exposure is dependent on orbitofrontal cortex (OFC)–basolateral amygdala (BLA) interactions. Here, we present evidence supporting the hypothesis that dopaminergic input from the ventral tegmental area (VTA) to the OFC critically regulates these interactions. In experiment 1, we employed site-specific pharmacological manipulations to show that dopamine D1-like receptor stimulation in the OFC is required for drug context-induced reinstatement of cocaine-seeking behavior following extinction training in an alternate context. Intra-OFC pretreatment with the dopamine D1-like receptor antagonist, {"type":"entrez-protein","attrs":{"text":"SCH23390","term_id":"1052733334","term_text":"SCH23390"}}SCH23390, dose-dependently attenuated cocaine-seeking behavior in an anatomically selective manner, without altering motor performance. Furthermore, the effects of {"type":"entrez-protein","attrs":{"text":"SCH23390","term_id":"1052733334","term_text":"SCH23390"}}SCH23390 could be surmounted by co-administration of a sub-threshold dose of the D1-like receptor agonist, {"type":"entrez-protein","attrs":{"text":"SKF81297","term_id":"1156277425","term_text":"SKF81297"}}SKF81297. In experiment 2, we examined effects of D1-like receptor antagonism in the OFC on OFC-BLA interactions using a functional disconnection manipulation. Unilateral {"type":"entrez-protein","attrs":{"text":"SCH23390","term_id":"1052733334","term_text":"SCH23390"}}SCH23390 administration into the OFC plus GABA agonist-induced neural inactivation of the contralateral or ipsilateral BLA disrupted drug context-induced cocaine-seeking behavior relative to vehicle, while independent unilateral manipulations of these brain regions were without effect. Finally, in experiment 3, we used fluorescent retrograde tracers to demonstrate that the VTA, but not the substantia nigra, sends dense intra- and interhemispheric projections to the OFC, which in turn has reciprocal bi-hemispheric connections with the BLA. These findings support that dopaminergic input from the VTA, via dopamine D1-like receptor stimulation in the OFC, is required for OFC–BLA functional interactions. Thus, a VTA–OFC–BLA neural circuit promotes drug context-induced motivated behavior.