Eleanor Brown

Inhibition of methylprednisolone elimination in the presence of clarithromycin therapy

Methylprednisolone elimination is reduced in the presence of treatment with troleandomycin (TAO), a macrolide antibiotic. To assess whether a similar interaction occurs with a more commonly used and less hepatotoxic macrolide antibiotic, erythromycin, we evaluated methylprednisolone pharmacokinetics before and after a 1 wk course of erythromycin base in nine adolescent patients with chronic asthma. These data were compared to results of studies of the troleandomycin methylprednisolone interaction evaluated in 10 adolescent asthmatic patients. Methylprednisolone clearance and apparent volume of distribution were significantly decreased and mean residence time and half-life significantly increased in the presence of both erythromycin and troleandomycin. The latter caused greater inhibition of methylprednisolone elimination. A nonlinear pattern of methylprednisolone disposition was observed in the presence of concomitant macrolide antibiotic administration. Addition of erythromycin base to methylprednisolone therapy results in inhibition of methylprednisolone elimination and may potentially increase the beneficial and adverse effects of this corticosteroid.

Clarithromycin potentiates glucocorticoid responsiveness in patients with asthma: results of a pilot study

BACKGROUND Selected macrolide antibiotics have steroid-sparing effects in patients with steroid-dependent asthma. In addition to inhibiting methylprednisolone clearance, macrolides may also display anti-inflammatory effects. OBJECTIVE To determine whether clarithromycin, by virtue of its anti-inflammatory effects, enhances glucocorticoid sensitivity. DESIGN Open-label, pilot study in a paired design (pre- and posttreatment). PARTICIPANTS Seven patients, mean age 27 (range 15 to 42 years), with mild to moderate asthma under good control. METHODS Clarithromycin (500 mg) was administered twice daily for 10 days with blood drawn for lymphocyte stimulation assays at baseline, and again upon completion of therapy. Lymphocytes were stimulated with phytohemagglutinin in the presence and absence of increasing concentrations of clarithromycin and dexamethasone (DEX). RESULTS At baseline, clarithromycin alone did not cause a significant degree of suppression of T-lymphocyte activation, yet clarithromycin significantly enhanced the sensitivity of lymphocytes to suppression by DEX as measured by a shift in the DEX dose-response curve by at least 6-fold (P = 0.04). In addition, a 10-day course of clarithromycin resulted in: 1) a significant decrease in the inhibitory concentration which results in a 50% reduction in proliferation for DEX alone, thereby increasing glucocorticoid sensitivity (P = 0.04); 2) heightened inhibitory effect of clarithromycin alone (P = 0.03); and 3) a sustained suppressive effect with the combination of clarithromycin and DEX on the inhibition of lymphocyte stimulation (P = 0.01). CONCLUSIONS Clarithromycin acts synergistically with DEX in suppressing lymphocyte activation. In addition, a 10-day course resulted in a significant treatment effect as evidenced by lower inhibitory concentration which results in a 50% reduction in proliferation value for DEX, a heightened response to clarithromycin alone, and a consistent degree of suppression of lymphocyte stimulation when clarithromycin and DEX were used together.

Coexistence of glucocorticoid receptor and pharmacokinetic abnormalities: Factors that contribute to a poor response to treatment with glucocorticoids in children with asthma

Rapid glucocorticoid clearance and abnormal glucocorticoid receptor binding have been described as factors that contribute to an inadequate response to treatment with glucocorticoids in patients with asthma. We report the coexistence of these abnormalities in children with severe asthma who respond poorly to systemic glucocorticoid therapy.

Delivery of glucocorticoids by jet nebulization: Aerosol characteristics and output

BACKGROUND Since inflammation has been identified as a critical factor in the pathogenesis of asthma, use of inhaled glucocorticoids has increased. Because young children are often unable to coordinate properly the use of metered-dose inhalers and no glucocorticoids preparations for nebulization have been approved in the United States, parenteral and intranasal glucocorticoids preparations are occasionally administered by nebulization. METHODS We examined whether a parenteral preparation (triamcinolone acetonide [TAA]; Kenalog) could be delivered by nebulization. TAA, 1000 micrograms (0.1 ml), was placed in the nebulizer bowl (MB5 [MeFar, Brescia, Italy] or Pari-Jet [Dura Pharmaceuticals, San Diego, Calif.]), then diluted with 2.9 ml normal saline solution for a total volume fill of 3 ml. Using a laser particle analyzer, high-performance liquid chromatography, and cascade impactor, we examined the percentage of aerosol volume produced with particles in the respirable range of 1 to 5 microns in diameter, actual TAA output (in micrograms) and concentration of TAA contained in the particles within the respirable range. RESULTS Laser particle analysis indicated that 34% +/- 3% (mean +/- SEM) (MB5) and 47 +/- 3% (Pari-Jet) of the total aerosol volume produced were within the respirable range of 1 to 5 microns in diameter, and this remained consistent throughout nebulization. The nebulizer was stopped serially for determination of TAA output with high-performance liquid chromatography. TAA output (1000 micrograms less the amount in micrograms remaining after nebulization) was essentially complete after 2 minutes with the Pari-Jet and within 4 minutes with the MB5 and totaled 352 +/- 19 micrograms and 367 +/- 9 micrograms, respectively. Finally, cascade impactor studies confirmed that 33.4% of the TAA aerosol generated by the MB5 nebulizer was contained in particles in the respirable range. CONCLUSION Approximately 35% (Pari-Jet) and 37% (MB5) of the initial 1000 micrograms of TAA was delivered with the two nebulizers tested. The particles generated within the respirable range were limited to 34% (MB5) and 47% (Pari-Jet) of the amount delivered. TAA was equally distributed in the particles generated. The theoretic amount delivered in the respirable range was approximately 12.5% for the MB5 nebulizer on the basis of the cascade impactor and 16.5% for the Pari-Jet (assuming TAA distribution equivalence) of the TAA placed in each of the nebulizers. Additional clinical studies are needed to define efficacy and safety in view of the excipients used in preparing the parenteral preparation.