L Lu un ng g d de ep po os si it ti io on n o of f b bu ud de es so on ni id de e f fr ro om m T Tu ur rb bu uh ha al le er r¤ ¤ i is s t tw wi ic ce e t th ha atABSTRACT: The pulmonary and systemic availability of budesonide after inhalation from a dry powder inhaler, Turbuhaler®, and from a pressurized metered-dose inhaler (P-MDI) were compared in healthy volunteers. Two different methods were used to assess pulmonary availability: 1) calculated from the systemic availability corrected for an oral availability of 13% (n=24); and 2) after blocking of gastrointestinal absorption by administration of a charcoal suspension (n=13). An intravenous infusion of budesonide was used as a reference.The systemic availability of budesonide, calculated as a geometric mean and expressed as percentage of the metered dose, was 38% for Turbuhaler® and 26% for P-MDI. The pulmonary availability, calculated using the first method, was 32% and 15% for Turbuhaler® and P-MDI, respectively; and, using the second method, 32% and 18%, respectively.The results of the present study indicate that administration of budesonide via Turbuhaler® gives rise to a lung deposition which is approximately twice that of a P-MDI, with less variability, but that systemic availability is only increased by approximately 50%. Thus, the present data suggest that by administrating budesonide via Turbuhaler®, instead of a P-MDI, the same degree of asthma control can be achieved with a lower dose, which, in turn, reduces the risk of undesired systemic effects.

This overview summarises available pharmacokinetic data on budesonide capsules (Entocort EC), approved for the treatment of mild-to-moderate active Crohn's disease involving the ileum and/or ascending colon and for prolongation of symptom control. Budesonide is a locally-acting glucocorticosteroid with an extensive, primarily hepatic, metabolism after oral administration. It is rapidly absorbed and biotransformed by cytochrome P450 (CYP) 3A to metabolites with negligible glucocorticoid activity. Entocort EC, a pH- and time-dependent oral formulation of budesonide, was developed to optimise drug delivery to the ileum and throughout the colon. Pharmaco-scintigraphic studies have confirmed that the Entocort EC formulation delays budesonide absorption and prolongs the rate of elimination but maintains complete absorption. This improves the delivery of budesonide to the intestinal lumen relative to a plain formulation. A low systemic availability of 9-21% indicates extensive first-pass elimination. Food appears to have little impact on the absorption of budesonide from Entocort EC capsules and the pharmacokinetics are dose-proportional between 3 and 15 mg. On average, systemic availability was 2.5-fold higher in patients with cirrhosis compared with healthy controls; however, mild liver impairment had little effect on systemic exposure. Pharmacokinetics appear unaffected by gender and age, although this has not been tested in younger children. Renal impairment is not expected to have an impact on the kinetics of Entocort EC. Budesonide is unlikely to inhibit the metabolism of other drugs, including CYP3A4 substrates, mainly because of the very low plasma concentrations obtained with the compound even after high doses of Entocort trade mark EC capsules. Strong CYP3A4 inhibitors, such as ketoconazole, will inhibit the metabolism of budesonide, resulting in several-fold increases in the area under the concentration-time curve of budesonide. Also, grapefruit juice intake may increase systemic availability of budesonide, probably by inhibition of intestinal CYP3A4 activity. Unlike prednisolone, oral contraceptives do not alter plasma budesonide concentrations. An increased pH obtained by gastric acid inhibitory drugs, such as omeprazole, does not affect the pharmacokinetics of budesonide. In summary, budesonide capsules (Entocort EC) possess many pharmacological features that make the formulation well adapted for a targeted treatment of inflammatory disorders, such as Crohn's disease involving the ileum and ascending colon.

Aims To determine the basal pharmacokinetics, lung uptake and plasma cortisol suppression for two commonly prescribed inhaled corticosteroids. Methods Twenty-one subjects (13 healthy and 8 mild asthmatic patients) received uticasone propionate via a chloro¯uorocarbon-propelled pressurized metered-dose inhaler (pMDI) (healthy subjects only) and Diskus 1 and budesonide via Turbuhaler 1 , 1000 mg twice daily for 7 days. Intravenous doses (200 mg) of both compounds were used as references. Plasma concentrations of¯uticasone and budesonide were determined during 48 h by liquid chromatography plus tandem mass spectrometry (LC-MS-MS). Plasma concentrations of cortisol were determined by LC-MS every second hour for 24 h at baseline, and following each treatment. Results The volume of distribution was found to be larger and the elimination half-life and mean absorption time longer for¯uticasone than for budesonide. The systemic availability of budesonide via Turbuhaler (39%) was signi®cantly higher than that of uticasone via Diskus (13%) (ratio 3.0 [2.5, 3.6] with 95% con®dence interval [CI]), and via pMDI (21%) (ratio 1.8 [1.3, 2.3]). In addition, at steady state the systemic availability of¯uticasone via pMDI was signi®cantly higher than via Diskus (ratio 1.6 [1.1, 2.2]). The lung deposition of budesonide via Turbuhaler was 2.2-fold [1.7, 2.9] higher than that of¯uticasone pMDI and 3.4-fold [2.8, 4.0] higher than that of uticasone Diskus. In addition, the lung deposition of¯uticasone via pMDI was 1.5-fold [1.1, 2.9] higher than that via the Diskus inhaler. Plasma cortisol (24 h) was signi®cantly reduced vs baseline for all three treatments. The cortisol concentration vs baseline was 12% for¯uticasone pMDI, which was signi®cantly lower (ratio 0.32 [0.24, 0.42]) than that for¯uticasone Diskus (39%), and for budesonide Turbuhaler (46%) (ratio 0.27 [0.21, 0.37]). The plasma cortisol concentration did not differ signi®cantly between treatments with¯uticasone Diskus and budesonide Turbuhaler (ratio 0.87 [0.65; 1.15]). Conclusions Budesonide and¯uticasone differ in their pharmacokinetic properties in that although clearance is the same, the rate of uptake and elimination is slower for uticasone. Despite a signi®cantly higher pulmonary availability of budesonide via Turbuhaler, the plasma cortisol suppression is less than that of¯uticasone via pMDI and similar to that of¯uticasone via Diskus. There is no indication of any difference between healthy subjects and mild asthmatic patients in the pharmacokinetics and plasma cortisol suppression of¯uticasone and budesonide.

Aims The present study was undertaken to see whether the difference in plasma cortisol suppression between single and repeated dosing of fluticasone propionate (FP) can be explained by systemic accumulation. Methods Twelve healthy subjects (six women) were given, in a crossover fashion, a single dose inhalation (1000 mg ) of FP via DiskhalerA and repeated inhalations (1000 mg twice daily) every 12 h during 7 days. There was a washout period of 2 weeks between the treatments. An intravenous dose of 20 mg FP was given as a reference. Plasma concentrations of FP for each treatment were determined by liquid chromatography plus tandem mass spectrometry. Plasma cortisol after the inhaled doses was determined using an immunoassay and was compared with baseline values. Results The average plasma concentration of FP was about 1.7 times higher after multiple inhalations than after a single dose. Systemic availability, mainly attributable to pulmonary deposition, was 15.6 [13.6-18.0]% of the nominal dose. Daytime plasma cortisol suppression vs baseline was 47 [20-65]% and 95 [93-97]% for the single and repeated doses, respectively. Conclusions To conclude, a slow elimination of FP leads to accumulation during repeated dosing. This accumulation may explain the marked decrease in plasma cortisol seen during treatment with fluticasone propionate within the clinical dose range.