Effect of rofecoxib on prednisolone and prednisone pharmacokinetics in healthy subjects

Randomized clinical trial comparing oral prednisone (50 mg) with placebo before laparoscopic cholecystectomy

BACKGROUND

Intravenous administration of dexamethasone 90 min before laparoscopic cholecystectomy improves surgical outcome but may be impractical. The objective of this study was to assess the clinical efficacy of oral self-administration of prednisone 2 h before ambulatory laparoscopic cholecystectomy.

METHODS

In a double-blind placebo-controlled study, 200 patients were randomized to oral administration of prednisone (50 mg) or placebo 2 h before laparoscopic cholecystectomy. Patients received a similar standardized anaesthetic, surgical, and analgesic treatment. The primary outcome was pain 24 h after surgery and secondary outcomes were fatigue and malaise 24 h after surgery. Outcome parameters were registered before operation, on the day of operation, and the following two days. Analgesic and antiemetic requirements were registered, and nausea and vomiting were assessed twice within the first 24 h. Side-effects and 30-day follow-up for morbidity were registered.

RESULTS

Data from 184 patients were available for statistical analysis. There were no significant differences in side-effects or complications between the surgical groups (P > 0.05). No significant intergroup differences in 24-h pain, fatigue or malaise scores or any other variables were found (P > 0.05).

CONCLUSION

There is no important clinical gain of preoperative oral steroid administration compared with placebo in patients undergoing laparoscopic cholecystectomy.

A Pharmacokinetic/Pharmacodynamic Approach to Predict Total Prednisolone Concentrations in Human Plasma

Prednisolone and prednisone are two widely used corticosteroids for various inflammatory and immune diseases. Prednisolone is the active form of prednisone in vivo. Total prednisolone in plasma exhibits nonlinear pharmacokinetics mainly due to its nonlinear protein binding. Other factors such as reversible metabolism (or interconversion between prednisolone and prednisone), competitive protein binding from endogenous cortisol, cortisol circadian rhythm, and prednisolone mediated cortisol suppression complicate prednisolone pharmacokinetics. This study was aimed to develop a new approach to describe the nonlinear pharmacokinetics of total prednisolone and predict total prednisolone concentrations in plasma. Based on literature datasets, a linear two-compartment pharmacokinetic model was developed to adequately describe the reversible metabolism between free prednisone and prednisolone. Cortisol and prednisolone protein binding were described via the sum of a Langmuir and linear type binding. The endogenous cortisol circadian rhythm and cortisol suppression during prednisone or prednisolone exposure were described with a previously reported linear release rate pharmacokinetic/pharmacodynamic (PK/PD) model. By combining the pharmacokinetic models for free prednisone and prednisolone, the linear release rate model for cortisol suppression, and competitive protein binding between cortisol and prednisolone, we were able to predict total prednisolone concentrations in plasma. The predicted total prednisolone concentrations in plasma were in good agreement with the literature reported data. Thus, this PK/PD approach shows that the combination of nonlinear protein binding, cortisol circadian rhythm, and cortisol suppression could account for the nonlinearity of total prednisolone. In addition, it also allows a valid prediction of total prednisolone in plasma after either prednisone or prednisolone administration.

Rofecoxib: an update on physicochemical, pharmaceutical, pharmacodynamic and pharmacokinetic aspects

Rofecoxib (MK-966) is a new generation non-steroidal anti-inflammatory agent (NSAID) that exhibits promising anti-inflammatory, analgesic and antipyretic activity. It selectively inhibits cyclooxygenase (COX)-2 isoenzyme in a dose-dependent manner in man. No significant inhibition of COX-1 is observed with rofecoxib up to doses of 1000 mg. The pharmacokinetics of rofecoxib has been found to be complex and variable. Mean oral bioavailability after single dose of rofecoxib (12.5, 25 or 50 mg) is 93% with t(max) varying widely between 2 and 9 h. It is highly plasma-protein bound and is metabolized primarily by cytosolic reductases to inactive metabolites. Rofecoxib is eliminated predominantly by hepatic metabolism with a terminal half-life of approximately 17 h during steady state. Various experimental models and clinical studies have demonstrated rofecoxib to be superior, or at least equivalent, in anti-inflammatory, analgesic and antipyretic efficacy to comparator nonselective NSAIDs in osteoarthritis, rheumatoid arthritis and other pain models. Emerging evidence suggests that rofecoxib may also find potential use as supportive therapy in various pathophysiologic conditions like Alzheimer's disease, and in various malignant tumours and polyps, where COX-2 is overly expressed. Rofecoxib is generally well-tolerated. Analysis of data pooled from several trials suggests that rofecoxib is associated with fewer incidences of clinically symptomatic gastrointestinal ulcers and ulcer complications vis-à-vis conventional NSAIDs. However, this gastropreserving effect may be negated by concurrent use of low-dose aspirin for cardiovascular risk reduction. Rofecoxib tends to show similar tolerability for renal and cardiothrombotic events as compared with nonnaproxen nonselective NSAIDs. No clinically significant drug interaction has been reported for rofecoxib except with diuretics, where it reverses their salt-wasting effect and thus can be clinically exploited in electrolyte-wasting disorders. There is only modest information about the physicochemical and pharmaceutical aspects of rofecoxib. Being poorly water soluble, its drug delivery has been improved using varied formulation approaches. Although it is stable in solid state, rofecoxib is photosensitive and base-sensitive in solution form with its degradation mechanistics elucidated. Analytical determinations of rofecoxib and its metabolites in biological fluids employing HPLC with varied types of detectors have been reported. Isolated studies have also been published on the chromatographic and spectrophotometric assay of rofecoxib and its degradants in bulk samples and pharmaceutical dosage forms. The current article provides an updated overview on the physicochemical, pharmaceutical, pharmacokinetic and pharmacodynamic vistas of rofecoxib.