A mass balance study to evaluate the biotransformation and excretion of [14C]-triamcinolone acetonide following oral administration

The principle objective of this study was to characterize the absorption, metabolism, and disposition of orally administered [14C]-triamcinolone acetonide. Six healthy male subjects each received a single 100 microCi (approximately 800 micrograms) oral dose of [14C]-triamcinolone acetonide. Plasma, urine, and fecal samples were collected at selected times and analyzed for triamcinolone acetonide and [14C]-derived radioactivity. Plasma protein binding of triamcinolone acetonide was also determined. Metabolite profiling and identification were carried out in plasma and excreta. Principle metabolites were assessed for activity with in vitro anti-inflammatory models. [14C]-triamcinolone acetonide was found to be systemically absorbed following oral administration. The presystemic metabolism and clearance of triamcinolone acetonide were extensive, with only a small fraction of the total plasma radioactivity being made up of triamcinolone acetonide. Little to no parent compound was detected in the plasma 24 hours after administration. Most of the urinary and fecally [14C]-derived radioactivity was also excreted within 24 and 72 hours postdose, respectively. Mean plasma protein binding of triamcinolone acetonide was constant, predictable, and a relatively low 68% over a 24-fold range of plasma concentrations. Three principle metabolites of triamcinolone acetonide were profiled in plasma, urine, and feces. These metabolites were identified as 6 beta-hydroxy triamcinolone, 21-carboxylic acid triamcinolone acetonide, and 6 beta-hydroxy-21-oic triamcinolone acetonide. All three metabolites failed to show any concentration-dependent effects in anti-inflammatory models evaluating IL-5-sustained eosinophil viability and IgE-induced basophil histamine release.

Nasal mucosal inflammation has no effect on the absorption of intranasal triamcinolone acetonide

The potential for enhanced systemic absorption of intranasal triamcinolone acetonide was explored in patients with inflamed nasal mucosa. Twelve allergic rhinitis patients with documented nasal inflammation, and 12 healthy volunteers, each received a single, therapeutic, 400-micrograms dose of triamcinolone acetonide in each nostril. Blood was obtained at fixed time points after the dose, and plasma concentrations of triamcinolone acetonide were determined by radioimmunoassay. There were no statistically significant differences in any of the derived pharmacokinetic parameters (maximum plasma triamcinolone acetonide concentrations [Cmax], time to maximum plasma triamcinolone concentrations [Tmax], elimination half-life [t1/2], and area under the plasma concentration-time curve [AUC0-12] from 0 to 12 hours) between treatment groups. A once-a-day, chronic regimen (6 weeks) of triamcinolone acetonide was also administered to five patients with allergic rhinitis. Pharmacokinetic parameters were similar to the parameters derived from healthy volunteers after acute administration. There was no evidence of drug accumulation. The results of this study indicate that acute and chronic intranasal administration. The results of this study indicate that acute and chronic intranasal administration of therapeutic doses of triamcinolone acetonide to patients with inflamed nasal mucosa does not result in enhanced systemic drug absorption or accumulation.

A pharmacokinetic study to evaluate the absolute bioavailability of triamcinolone acetonide following inhalation administration

Triamcinolone acetonide is a glucocorticoid administered by oral inhalation in the management of asthma. With oral inhalation of glucocorticoids, systemic absorption can come from oropharyngeal, gastrointestinal, or airway deposition of the drug. The objectives of this study were to determine the absolute bioavailability of triamcinolone acetonide following inhalation administration and to delineate the airway contribution of triamcinolone acetonide absorption relative to the absolute bioavailability. All subjects received a 5-minute 400 mcg intravenous infusion of triamcinolone acetonide and a single 800 mcg dose of inhaled triamcinolone acetonide with and without oral charcoal administration in a randomized three-way crossover fashion. The oral charcoal allowed for isolating the pulmonary component of absorption by adsorbing the oropharyngeal and gastrointestinal deposited drug. The mean (+/- SD) absolute bioavailability value for inhaled triamcinolone acetonide was 25% (8.75%). Delineation of the airway contribution of triamcinolone acetonide absorption showed that 10.4% of an inhaled dose is absorbed as triamcinolone acetonide from the lungs. Mean (+/- SD) total body clearance was rapid at 0.57 (0.12) L/hr/kg. The mean (+/- SD) apparent volume of distribution following the intravenous dose was a low 1.96 (0.31) L/kg. No significant differences were noted in the apparent terminal elimination half-life of triamcinolone acetonide (approximately 2.4 hr) between treatments.

A study comparing the clinical pharmacokinetics, pharmacodynamics, and tolerability of triamcinolone acetonide HFA-134a metered-dose inhaler and budesonide dry-powder inhaler following inhalation administration

The impending phaseout of chlorofluorocarbons as propellants in pressurized metered-dose inhalers used in the treatment of asthma has resulted in the development of alternative devices to deliver drug to the pulmonary airways. These alternative devices include metered-dose inhalers using environmentally friendly hydroflurocarbon propellants and breath-actuated dry-powder inhalers. The purpose of this study was to compare the single- and multiple-dose pharmacokinetics, pharmacodynamics, and tolerability of a newly developed hydroflurocarbon formulation of triamcinolone acetonide (Azmacort HFA 225 mcg Inhalation Aerosol) to that of the dry-powder formulation of budesonide (Pulmicort Turbuhaler 200 mcg). This three-way crossover study used 18 normal healthy subjects each receiving a 675 mcg dose of triamcinolone acetonide, 600 mcg dose of budesonide, or placebo twice a day for 5 days. Serial plasma samples were collected after the first and last dose of test medication for pharmacokinetic analysis. Pharmacodynamics were assessed by changes in hypothalamic-pituitary-adrenal axis function as measured by 8 a.m. serum cortisol, 24-hour overnight serum cortisol AUC(0-24), and 24-hour urinary-free cortisol after the last evening dose of test drug. Tolerability was assessed through physical examinations, vital signs, 12-lead ECG, routine clinical labs, and adverse events recording. Both compounds were systemically absorbed. However, no significant drug accumulation was noted with chronic dosing. Chronic dosing did result in a statistically significant 20% reduction in basal 24-hour serum cortisol AUC(0-24) for both compounds. There were no clinically significant abnormalities in physical examination, vital signs, 12-lead ECG, or routine clinical labs noted during the study. Overall, the study drugs were well tolerated, with adverse events characterized as mild to moderate in severity.

Pharmacokinetics and electrocardiographic effect of ebastine in young versus elderly healthy subjects

The objective of this study was to compare the single- and multiple-dose pharmacokinetics and electrocardiographic effect of a 10-mg oral dose of ebastine in elderly (ages, 65-85 years) and young (ages, 18-35 years) healthy volunteers. Thirty-seven subjects completed this randomized, double-blind, multiple-dose, placebo-controlled, parallel group study. The elderly group consisted of 18 subjects, with 13 subjects receiving 10 mg ebastine and 5 receiving matching placebo. The young group consisted of 19 subjects, with 13 subjects receiving 10 mg ebastine and 6 receiving matching placebo. On study days 1 and 3 through 10, each subject received a single 10-mg dose of ebastine or matching placebo in the morning with a standard breakfast. No drug was administered on study day 2 because of pharmacokinetic sampling. Blood samples were collected at selected times postdose on study days 1, 2, and 10. Plasma samples were analyzed for ebastine and its active metabolite, carebastine, using a validated high-performance liquid chromatography method. No plasma ebastine concentrations were detected, suggesting essentially complete metabolic conversion of ebastine to its metabolites. Analysis of variance showed no statistically significant differences between young and elderly single- and multiple-dose carebastine pharmacokinetics with respect to area under the plasma concentration-time curve, maximum concentration (Cmax ), terminal elimination rate constant, apparent oral clearance, or apparent volume of distribution. The mean time of maximum concentration value for young subjects was 1 hour longer than that for elderly subjects after single-dose administration but was comparable after multiple-dose administration. Within-group comparisons of both the young and elderly showed that pharmacokinetics between single dose and steady state were not statistically different. However, the mean steady-state carebastine Cmax values were approximately twofold greater than the mean Cmax values obtained after single-dose administration. A twofold increase in Cmax values between single-dose and steady-state administration is predicted for drugs such as carebastine, because its input interval is approximately equal to its elimination half-life. Twelve-lead electrocardiography was performed before dosing on day 1 and repeated 4 hours postdose on days 1, 5, and 10. Twenty-four hour Holter monitoring was also performed before and at the end of the study. No clinically relevant findings were found by electrocardiography or Holter monitoring between ebastine and placebo in the elderly and young subjects.

The pharmacokinetics and pharmacodynamics of desmopressin: effect on plasma factor VIII:C and von Willebrand factor

The relationship between plasma concentrations of desmopressin and clotting factors Factor VIII:C (FVIII:C) and von Willebrand Factor (vWF) were explored after a single 15-minute intravenous infusion of desmopressin (0.3 microg/kg) to 28 healthy male subjects. Individual plasma desmopressin-vWF and desmopressin-FVIII:C concentration/response-time data were fitted to a pharmacodynamic sigmoid E ( max ) model linked to a two-compartment open pharmacokinetic model (Ke0 link). The model demonstrated that the onset rate of pharmacodynamic activity for FVIII:C and vWF was relatively rapid following intravenous administration. However, the offset rate of pharmacodynamic activity was rate-limited by the elimination rate of desmopressin. Mean maximum pharmacodynamic activity for both factors was estimated to be three- to four-times higher than baseline activity, and the mean desmopressin concentrations that produce half-maximal effects were approximately 250 to 300 pg/mL. Interindividual variation in pharmacodynamic-parameter estimates were of the magnitude that suggests a wide range of pharmacodynamic responses are possible for a fixed desmopressin dose.

Measurement of low picomolar levels of triamcinolone acetonide in human bronchoalveolar lavage fluid by gas chromatography-electron-capture negative-ion mass spectrometry

The intense inherent electron-capture properties of the C21 acetate derivative of triamcinolone acetonide (TAA) under methane chemical ionization mass spectrometric conditions were exploited for the development of a highly sensitive and selective gas chromatography-mass spectrometric (GC-MS) technique for measurement of levels of TAA in human bronchoalveolar lavage (BAL) fluid. After the addition of 3.0 ng of a heptadeuterated analog of TAA and varying concentrations of TAA to 2-ml aliquots of BAL fluid, the deuterium and protium forms of the steroid were extracted with diethyl ether, converted to the C21 acetate derivative, and purified via adsorptive chromatography prior to GC-MS analysis. Standard curves obtained from 2-ml aliquots of BAL fluid were linear over a wide range of concentrations of TAA from 0.0 to 24,600 pg/2-ml aliquots of BAL fluid. Levels as low as 6.0 pg/ml (13.8 pmol x L(-1)) in BAL fluid can be reliably determined in 2-ml aliquots of the biological fluid with <10% error. These findings suggest that the assay method exploiting the intense electron-capture properties of TAA is highly suitable for determination of the deposition pattern and in vivo kinetics of TAA in human airways following inhalation of the steroid.

Delivery of toll-like receptor agonists by complement C3-targeted liposomes activates immune cells and reduces tumour growth

Activation of antigen presenting cells (APCs) is necessary for immune recognition and elimination of cancer. Our lab has developed a liposome nanoparticle that binds to complement C3 proteins present in serum. These C3-liposomes are specifically internalised by APCs and other myeloid cells, which express complement C3-binding receptors. Known immune stimulating compounds, toll-like receptor (TLR) agonists, were encapsulated within the C3-liposomes, including monophosphoryl lipid A (MPLA), R848, and CpG 1826, specific for TLR4, TLR7/8, and TLR9 respectively. When recognised by their respective TLRs within the myeloid cells, these compounds trigger signal cascades that ultimately lead to increased expression of inflammatory cytokines and activation markers (CD80, CD83, CD86 and CD40). RT-PCR analysis of murine bone marrow cells treated with C3-liposomes revealed a significant increase in gene expression of pro-inflammatory cytokines and factors (IL-1β, IL-6, IL-12, TNF-α, IRF7, and IP-10). Furthermore, treatment of 4T1 tumour-bearing mice with C3-liposomes containing TLR agonists resulted in reduced tumour growth, compared to PBS treated mice. Collectively, these results demonstrate that C3-liposome delivery of TLR agonists activates APCs and induces tumour-specific adaptive immune responses, leading to reduced tumour growth in a breast cancer model.

Managerial perceptions of the incentives inherent in National Health Service capital charging

Capital charging was introduced into the National Health Service (NHS) in 1991 in order to stop capital being treated as a 'free' good and to encourage managers to use their assets more efficiently. This article seeks to examine the extent to which managerial thinking has been influenced. It uses as evidence interviews with NHS managers conducted in Scotland in 1994. The following uses of capital charges data are explored: capital programme; disposal programme; maintenance programme; contract pricing; and budgetary devolution. New capital programmes required more justification and capital charges were seen as relevant to estate rationalization. Less effect was found with regard to the maintenance programme, though this may have been due to a downgrading of the estates function in most Trusts. Although the capital charge costs included in contract prices affect the competitive position of providers, there was criticism of the lack of development of the purchasing function. Budgetary devolution was proceeding relatively slowly but, among those Trusts which had devolved capital charges, evidence was found that some clinicians were becoming aware of the full costs of equipment use. This article concludes, with cautious optimism, that capital charges are beginning to influence decisions and that, despite some incentives being dysfunctional, they will lead to a better managed NHS.

Bradycardia associated with meningioma in a dog

Clinical signs of bradycardia and syncope, associated with intracranial meningioma, were observed in a 4-year-old female Irish Setter. Electrocardiographic abnormalities confirming bradycardia and suggestive of sinoatrial arrest were demonstrated. Return to a normal heart rate and sinus rhythm after administration of atropine IV indicated that increased vagal tone was responsible for the observed abnormalities. Neither glycopyrrolate nor propantheline bromide therapy was successful in controlling bradycardia and syncope. Necropsy findings included the demonstration of a 3 X 2 X 2-cm mass on the ventral aspect of the right half of the brain. This mass covered half of the mammillary body and extended as a thick reddish brown membrane extending over the piriform lobe of the cerebrum, optic chiasm, and longitudinal fissure. Histologically, the mass was identified as a meningotheliomatous meningioma.

Steady-state dose proportionality of a once-a-day sustained-release diltiazem hydrochloride formulation in healthy subjects

In this open-label, randomized, cross-over study, 12 healthy subjects received four doses of a new sustained-release formulation of diltiazem hydrochloride for six consecutive days. Blood samples were drawn on days 5 and 6 for determination of plasma diltiazem and desacetyldiltiazem levels. The peak concentrations after 120, 240, 360, and 480 mg of diltiazem were 48.1, 112.6, 180.9, and 276.8 ng/ml, respectively, while the mean minimum concentrations were 6.3, 14.6, 24.9, and 44.6 ng/ml. The areas under the concentration-time curves were 702, 1,642, 2,622, and 4,004 ng.hr/ml. Prolonged, continuous absorption of diltiazem was noted over the 24-hour dosing period. The dose-adjusted mean steady-state plasma diltiazem levels after the four doses were significantly different, consistent with diltiazem's nonlinear absorption, but the plasma profiles were similar, indicating that the diltiazem release rate was not dose-dependent. Therapeutic plasma diltiazem levels (greater than or equal to 40 ng/ml) were maintained for 24 hours after the three larger doses. The changes in the pharmacokinetics of desacetyldiltiazem over the four diltiazem doses were similar to those of diltiazem. The number of adverse treatment experiences tended to increase with the higher doses, but none were severe. The results indicate that, according to their pharmacokinetic profiles, doses of 240 mg to 480 mg of diltiazem are suitable for once-daily administration.

Multicenter evaluation of the efficacy and safety of sustained-release diltiazem hydrochloride for the treatment of hypertension

In a double-blind study, patients with mild-to-moderate hypertension were randomly assigned to receive placebo or increasing daily doses of a new sustained-release formulation of diltiazem: 180 mg, 360 mg, and 540 mg, each once daily for two weeks. The numbers of evaluable patients were 26 in the placebo group and 81 in the diltiazem group at week 2, 24 and 75 at week 4, and 23 and 65 at week 6. Changes from baseline in mean supine trough (before drug administration) systolic/diastolic blood pressures were +1.3/-2.7 mmHg after placebo and -4.7/-6.1 mmHg after diltiazem at week 2; -0.1/-1.7 mmHg after placebo and -7.2/-9.3 mmHg after diltiazem at week 4; and +0.4/-1.7 mmHg after placebo and -6.7/-10.2 mmHg after diltiazem at week 6. The changes were significantly greater after diltiazem than placebo. Increasing the daily dose of diltiazem from 360 mg to 540 mg produced more than proportional increases in mean plasma diltiazem concentrations but only minimal further reductions in blood pressure. Similar rates of adverse experiences were reported by the diltiazem-treated and placebo patients. Treatment was withdrawn in two diltiazem-treated patients because of abnormal electrocardiographic (ECG) changes that were considered to be related to the drug: elevated ST segment in one and first-degree atrioventricular block in the other. No other treatment-related ECG changes were noted. It is concluded that this new once-daily formulation of diltiazem is safe and effective in the treatment of mild-to-moderate hypertension.