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.     

Prednisolone disposition in steroid-dependent asthmatic children

The pharmacokinetics of a 40-mg intravenous dose of prednisolone were determined in 10 steroid-dependent asthmatic children with highly variable prednisone requirements (5 mg every other day to 40 mg a day). Concentrations of prednisolone and cortisol in plasma over a 24-hr test period were measured by high-performance liquid chromatography. Eosinophil concentrations and the concentration-dependent protein binding of prednisolone were also determined. The mean (±SD) apparent half-life of prednisolone in these children was 2.5 ± 0.5 hr. The mean total volume of distribution was 52.8 ± 14.5 L/1.73 m² and mean plasma clearance was 246 ± 62 ml/min/1.73 m². These pharmacokinetic parameters, as well as the protein binding and eosinopenic response, were similar to values from healthy and steroid-dependent asthmatic adults. The data were also similar in both responsive and relatively resistant patients. The pharmacokinetics and protein binding of prednisolone are not responsible for the highly variable prednisone requirement and clinical response of these children to prednisone therapy.     

The effect of troleandomycin on methylprednisolone elimination

Troleandomycin (TAO), a macrolide antibiotic, has an apparent “steroid-sparing” effect when used in the treatment of severe steroid-dependent asthma. This study was designed to investigate the effect of TAO on methylprednisolone elimination. Pharmacokinetic studies were performed before and 1 wk after starting TAO in 10 severe steroid-dependent asthmatics. Baseline total body clearance of methylprednisolone was 406 ± 139 (mean ± SD) ml/min/1.73 m² and decreased significantly (p < 0.001) to 146 ± 57 ml/min/1.73 m² 1 wk after TAO therapy was initiated. Methylprednisolone half-life was 2.46 ± 0.75 hr before TAO and increased significantly (p < 0.001) to 4.63 ± 1.35 hr after 1 wk on TAO therapy. A follow-up evaluation of methylprednisolone pharmacokinetics in three patients after at least 1 mo on TAO therapy demonstrated continuation of the reduced methylprednisolone elimination. TAO inhibition of methylprednisolone clearance may contribute to the beneficial effects observed initially with combined methylprednisolone-troleandomycin therapy in severe steroid-dependent asthma.     

Fluticasone propionate powder and lack of clinically significant effects on hypothalamic-pituitary-adrenal axis and bone mineral density over 2 years in adults with mild asthma

BACKGROUND: Although inhaled corticosteroids are widely used for the treatment of inflammation in asthma, prospective, long-term, placebo-controlled trials characterizing their systemic safety with chronic use are lacking. OBJECTIVE: This study was designed to prospectively evaluate the long-term safety of inhaled fluticasone propionate therapy. METHODS: Fluticasone propionate powder, 500 microgram, or placebo was administered twice daily by means of the Diskhaler for 104 weeks to 64 adults with mild persistent asthma in a randomized, double-blind, parallel-group study. Primary safety variables were measured at baseline and every 6 months thereafter. Although evaluation of efficacy was not an objective of this study, pulmonary function testing was performed at monthly intervals. RESULTS: Two years of treatment with fluticasone propionate had no significant effects on the skeletal system. No clinically significant changes were observed in ophthalmic parameters (glaucoma and posterior subcapsular cataracts). Mean change from baseline in lumbar spine (L1 to L4 ) bone density at week 104 was not significantly different between fluticasone propionate (-0.006 +/- 0.008 g/cm2) and placebo (-0.007 +/- 0.010 g/cm2). Markers of bone formation (serum osteocalcin) and resorption (urinary N-telopeptide) did not differ significantly between treatment groups. The effects of fluticasone propionate treatment on the hypothalamic-pituitary-adrenal axis were minimal, with no alterations in morning plasma cortisol concentrations and minor but statistically significant decreases in poststimulation mean peak plasma cortisol concentrations (P =.021) and 8-hour plasma cortisol area under the curve values (P =.020) at week 104. Drug-related adverse events were primarily topical effects of inhaled corticosteroids. Pulmonary function improved significantly during 2 years of fluticasone propionate treatment. CONCLUSION: Fluticasone propionate powder, 500 microgram twice daily for up to 2 years, was efficacious and well tolerated, with no clinically relevant effects on the hypothalamic-pituitary-adrenal axis, bone density, or ophthalmic parameters in adults with mild asthma.     

Effect of low-dose methotrexate on the disposition of glucocorticoids and theophylline

Low-dose methotrexate (MTX) therapy has been recently proposed as alternative therapy for patients with severe steroid-requiring asthma. Several questions have been raised regarding the mechanism of action, including alteration of pharmacokinetics of two medications used in these patients, specifically, glucocorticoids and theophylline. To address this question, pharmacokinetic studies were performed at baseline and after 6 weeks of treatment with either intramuscular MTX or placebo (folic acid). Plasma concentrations of theophylline were measured by fluorescence polarization immunoassay (TDx, Abbott Diagnostics, Abbott Park, Ill.). Prednisolone, methylprednisolone, and cortisol concentrations were measured by high-performance liquid chromatography. Fifteen adults were enrolled in the double-blind, placebo-controlled trial. No change in prednisolone pharmacokinetic parameters was found. Theophylline clearance decreased an average of 19% in patients randomized to receive MTX, from 48.0 +/- 2.0 ml/hr/kg to 38.9 +/- 3.6 ml/hr/kg (p less than 0.05). This change resembles change observed with theophylline and phenobarbital clearance in which a high degree of interpatient variability is observed. The most likely explanation for the change in theophylline clearance is inhibition of hepatic microsomal enzyme activity. Three patients complained of adverse effects, and dosage was reduced in one patient. The variable effect of MTX on theophylline clearance indicates that theophylline concentration monitoring should be performed in patients receiving both drugs.     

Effects of allergen inhalation and oral glucocorticoid on serum soluble CTLA-4 in allergic asthmatics

BACKGROUND: The serum soluble cytotoxic T lymphocyte associated antigen-4 (sCTLA-4) concentration is significantly elevated in patients with asthma, and sCTLA-4 concentration correlate with the severity of asthma. The aim of the present study was to investigate effects of allergen inhalation and oral glucocorticoid on concentration of serum sCTLA-4 in patients with allergic asthma. METHODS: Allergen inhalation challenge was conducted in allergic asthmatics with isolated early asthma response and those with dual asthma response. In a randomized, double-blind, placebo-controlled, parallel group fashion, prednisolone or placebo was give orally once a day for 2 weeks. Venous blood samples were collected before and after allergen inhalation or prednisolone administration for obtaining sera. The serum sCTLA-4 concentrations were determined using enzyme-linked immunosorbent assay. RESULTS: The serum sCTLA-4 concentrations in the dual responder group increased from 29.0 (14.5-43.7) microg/l [median (25-75 percentiles)] before allergen inhalation to 44.0 (24.3-61.3) microg/l 24 h after allergen inhalation. In the isolated early responders, there were no significant increase in serum sCTLA-4 concentrations after allergen inhalation compared with baseline levels. There was a significant decrease in serum sCTLA-4 concentrations after 2 weeks of glucocorticoid therapy [22.0 (15.5-31.0) microg/l] compared with baseline values [37.0 (19.5-53.0) microg/l], whereas there was no significant difference in the placebo group. CONCLUSION: This study has demonstrated that serum sCTLA-4 concentrations increased after allergen inhalation in sensitized asthmatic subjects, and that serum sCTLA-4 concentrations were downregulated by prednisolone therapy.     

Glucocorticoid resistance in asthma is associated with elevated in vivo expression of the glucocorticoid receptor beta-isoform

BACKGROUND: Glucocorticoid-resistant bronchial asthma is characterized by failure of corticosteroids to suppress key asthma-relevant, cell-mediated inflammatory responses in the airways. OBJECTIVE: The mechanism of this phenomenon is not clear but may involve aberrant expression of the beta-isoform of the glucocorticoid receptor. METHODS: We have measured expression of the alpha- and beta-glucocorticoid receptor isoforms in tuberculin-driven cutaneous cell-mediated inflammatory lesions in people with asthma who are glucocorticoid sensitive and resistant after 9 days of therapy with oral prednisolone (40 mg/day) or matching placebo in a random order, crossover design. RESULTS: After placebo therapy, the mean numbers of cells expressing glucocorticoid receptor alpha immunoreactivity in the lesions evoked in glucocorticoid-sensitive and -resistant patients with asthma were statistically equivalent. The numbers of cells expressing glucocorticoid receptor beta were significantly elevated in the patients who were glucocorticoid resistant, resulting in an 8-fold higher ratio of expression of glucocorticoid receptor alpha/glucocorticoid receptor beta in the patients who were glucocorticoid sensitive. Glucocorticoid receptor alpha/glucocorticoid receptors beta were colocalized to the same cells. Oral prednisolone therapy was associated with a significant decrease in the numbers of cells expressing glucocorticoid receptor alpha but not glucocorticoid receptor beta in the subjects who were glucocorticoid sensitive. No significant change was found in the numbers of cells expressing glucocorticoid receptor alpha and glucocorticoid receptor beta in the patients who were glucocorticoid resistant. Prednisolone therapy reduced the ratio of glucocorticoid receptor alpha/glucocorticoid receptor beta expression for the patients who were glucocorticoid sensitive to a level seen in the patients who were glucocorticoid resistant before therapy. CONCLUSION: Because glucocorticoid receptor beta inhibits alpha-glucocorticoid receptor-mediated transactivation of target genes, the increased expression of glucocorticoid receptor beta in inflammatory cells might be a critical mechanism for conferring glucocorticoid resistance.     

Prednisolone pharmacokinetics in the presence and absence of ritonavir after oral prednisone administration to healthy volunteers

Corticosteroid therapy has been associated with bone toxicities (eg, osteonecrosis) and Cushing syndrome in HIV-infected patients; this may be partially attributable to a pharmacokinetic drug interaction between HIV protease inhibitors and corticosteroids. The purpose of this study was to characterize the influence of low-dose ritonavir on prednisolone pharmacokinetics in healthy subjects. Ten HIV-seronegative volunteers were given single oral doses of prednisone, 20 mg, before (baseline) and after receiving ritonavir, 200 mg, twice daily for 4 and 14 days. After each prednisone dose, serial blood samples were collected and prednisolone concentrations were determined; pharmacokinetic parameter values were compared between the groups. Geometric mean ratios (GMRs, 90% confidence interval [CI]) of the prednisolone area under the plasma concentration versus time curve (AUC0-infinity) after 4 and 14 days of ritonavir versus baseline were 1.41 (90% CI: 1.08 to 1.74) and 1.30 (90% CI: 1.09 to 1.49), respectively (P = 0.002 and P = 0.004, respectively). GMRs of prednisolone apparent oral clearance (Cl/F) were 0.71 (09% CI: 0.57 to 0.93) and 0.77 (90% CI: 0.67 to 0.92) after 4 and 14 days of ritonavir versus baseline, respectively (P = 0.0004 and P = 0.0003, respectively). Ritonavir significantly increased the systemic exposure of prednisolone in healthy subjects. Results from this investigation suggest that corticosteroid exposure is likely elevated in HIV-infected patients receiving protease inhibitors.     

Effect of low-dose troleandomycin on glucocorticoid pharmacokinetics and airway hyperresponsiveness in severely asthmatic children

Fifteen hospitalized asthmatic children (8 to 18 years old) completed a 2-week randomized, parallel, double-blind placebo-controlled comparison of combination methylprednisolone and placebo troleandomycin, prednisone and troleandomycin (P-TAO) or methylprednisolone-TAO (MPn-TAO). Troleandomycin (250 mg once daily or every other day) and glucocorticoid doses were reduced by a standard protocol. Symptom scores, blood chemistries, pulmonary function tests, airway response to methacholine, and glucocorticoid pharmacokinetics were compared. In each group, a steroid dose reduction of 50% was achieved without a deterioration in symptom scores. Methacholine response was unchanged in all five on methylprednisolone alone, but decreased 3-fold to 30-fold in two of five on combination P-TAO, and four of five on combination MPn-TAO. Troleandomycin decreased MPn clearance by an average of 62% but did not alter prednisolone clearance. Low-dose TAO combined with MPn has a significant effect on methylprednisolone clearance in children, an effect equivalent to that reported with higher dose TAO (1000 mg/d) therapy. In addition, this preliminary study suggests that TAO may decrease bronchial hyperresponsiveness to methacholine in severely asthmatic children.     

Methylprednisolone pulse therapy in acute severe asthma

Methylprednisolone pulse therapy (MPPT) has been shown to possess a long-lasting effect in other immune-inflammatory diseases without the well-known side effects caused by long-term treatment with glucocorticosteroids. In an attempt to reduce the long-term use of oral steroids in asthmatics, we conducted this double-blind, double-dummy study to compare the use of MPPT (1 g of methylprednisolone intravenously) (8 patients) with a short course of oral prednisolone (10 patients) in asthmatics presenting with acute severe asthma. Both treatments were effective in relieving the acute attack of asthma. The MPPT-treated patients did not show a faster resolution than did the orally treated group. No patients needed assisted ventilation, and no deaths occurred. One week after the treatment FEV1 tended to decrease in the methylprednisolone group compared with the oral prednisolone group (P = 0.06). The patients initially receiving MPPT needed supplementary prednisolone earlier and in higher doses than did the patients receiving oral prednisolone as initial treatment. At the end of the 12 weeks' study period, the groups reached identical FEV1. In conclusion, we did not find intravenous methylprednisolone superior to oral prednisolone in the treatment of acute attacks of severe asthma, but methylprednisolone pulse therapy had a shorter duration as regards protection against future asthma attacks.     

Correlation between the results of glucocorticoid therapy and in vitro effect of glucocorticoids on monocytes in asthma

The effects of glucocorticoids on monocyte morphology and function in vitro and the results of high-dose budesonide therapy in patients with non-severe bronchial asthma were analyzed. Before therapy with inhalation glucocorticosteroid (budesonide) characteristics of blood monocytes and the effects of different concentrations of prednisolone on these cells were studied in vitro by luminol-dependent chemiluminescence and computer-assisted phase-interference microscopy. High sensitivity of patients to budesonide was associated with pronounced in vitro inhibitory effect of prednisolone on monocyte activity, which was not observed in cases with delayed effects of therapy. Pronounced inhibitory effects of glucocorticoids on monocytes in vitro were observed in patients both resistant and highly sensitive to glucocorticoid therapy. Hence, the resistance of patients with non-severe asthma to high-dose budesonide therapy is not related to the weakening of the inhibitory effect of glucocorticoids on monocyte activity.     

Corticosteroid resistance in mild asthma: markers of persistent inflammation.

BACKGROUND: Bronchial hyperresponsiveness (BHR) is an important feature of asthma. Glucocorticosteroids (GCS) reduce BHR, probably by suppressing allergic inflammation. There are, however, two groups of asthmatics with either GCS-responsive or non-responsive BHR to methacholine. We investigated the mechanism of non-GCS-responsive BHR in mild asthma. METHODS: Non-GCS-responsive BHR asthma was defined as failure of reduction of BHR to methacholine after a 2-week course of oral prednisolone (30 mg/day). The expression of interleukin (IL)-4, IL-5, IFN-gamma mRNA in peripheral blood mononuclear cells, eosinophil count, serum cortisol, eosinophilic cationic protein (ECP), and spirometry were measured in five non-GCS-responsive BHR asthmatics and six patients with GCS-responsive BHR asthma before and after prednisolone therapy. RESULTS: With the exception of serum ECP and expression of IL-5 mRNA, no significant differences were observed between GCS-responsive BHR and non-GCS-responsive BHR asthma. The mean ECP level was significantly higher in non-GCS-responsive BHR than in GCS-responsive BHR asthma before and after prednisolone therapy. Interleukin-5 mRNA was detected in all asthmatics before prednisolone therapy; however, after prednisolone therapy, IL-5 mRNA was only detected in non-GCS-responsive BHR asthmatics. CONCLUSIONS: Our findings suggest that activation of eosinophils appears to persist in some asthmatics with non-GCS-responsive BHR due to continuous IL-5 production by lymphocytes.     

Inhibition of methylprednisolone elimination in the presence of erythromycin 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.     

Steroid-specific and anticonvulsant interaction aspects of troleandomycin-steroid therapy

Troleandomycin (TAO) is a macrolide antibiotic that has an apparent “steroid-sparing” effect when used in the treatment of severe steroid-dependent asthmatic patients. Recent observations demonstrated the effect of TAO on inhibiting methylprednisolone elimination, possibly contributing to its beneficial effects. Prednisolone and methylprednisolone disposition were studied before and 1 wk after initiation of TAO therapy in three patients. Methylprednisolone elimination was characteristically impaired in the presence of TAO therapy; however, there was no apparent effect on prednisolone elimination. Methylprednisolone elimination was also evaluated before and after initiation of TAO therapy in three patients receiving concomitant anticonvulsant therapy with phenobarbital-1, phenytoin-2. Methylprednisolone clearance before TAO was at least 4 times faster than normal and was probably related to enzyme induction by the anticonvulsant medication. Methylprednisolone clearance was subsequently reduced by approximately 70% in the presence of TAO therapy. The effect of TAO on corticosteroid disposition is steroid-specific and TAO can diminish the effect of certain drugs on the induction of corticosteroid metabolism.     

Effects of allergen inhalation and oral glucocorticoid on concentrations of serum-soluble CD86 in allergic asthmatics

The aim of the present study was to investigate effects of allergen inhalation and oral glucocorticoid on concentration of serum soluble CD86 in patients with allergic asthma. Our results showed that the serum soluble CD86 concentrations in the dual responder group increased from 491.8 +/- 15.4 IU/ml before allergen inhalation to 603.8 +/- 19.3 IU/ml 24 h after allergen inhalation. In the isolated early responders, there was no significant increase in serum soluble CD86 concentrations after allergen inhalation compared with baseline levels. There was a significant decrease in serum soluble CD86 concentrations after 2 weeks of glucocorticoid therapy (448.3 +/- 15.1 IU/ml) compared with baseline values (532.7 +/- 12.3 IU/ml), whereas there was no significant difference in the placebo group. This study has demonstrated that serum soluble CD86 concentrations increased after allergen inhalation in sensitized asthmatic subjects, and that serum sCD86 concentrations were downregulated by prednisolone therapy.     

Improved bronchodilation with levalbuterol compared with racemic albuterol in patients with asthma

Background: Racemic albuterol is an equal mixture of (R)-albuterol (levalbuterol), which is responsible for the bronchodilator effect, and (S)-albuterol, which provides no benefit and may be detrimental. Objective: We sought to compare 2 doses of a single enantiomer, levalbuterol (0.63 mg and 1.25 mg), and equivalent amounts of levalbuterol administered as racemic albuterol with placebo in patients with moderate-to-severe asthma. Methods: This was a randomized, double-blind, parallel-group trial. Three hundred sixty-two patients 12 years of age or older were treated with study drug administered by means of nebulization 3 times daily for 28 days. The primary endpoint was peak change in FEV₁ after 4 weeks. Results: The change in peak FEV₁ response to the first dose in the combined levalbuterol group was significantly greater compared with the combined racemic albuterol group (0.92 and 0.82 L, respectively; P = .03), with similar but nonsignificant results after 4 weeks (0.84 and 0.74 L, respectively). Improvement in FEV₁ was similar for levalbuterol 0.63 mg and racemic albuterol 2.5 mg and greatest for levalbuterol 1.25 mg. Racemic albuterol 1.25 mg demonstrated the weakest bronchodilator effect, particularly after chronic dosing. The greatest increase in FEV₁ was seen after levalbuterol 1.25 mg, especially in subjects with severe asthma. All active treatments were well tolerated, and β-adrenergic side effects after administration of levalbuterol 0.63 mg were reduced relative to levalbuterol 1.25 mg or racemic albuterol 2.5 mg. At week 4, the predose FEV₁ value was greatest in patients who received levalbuterol or placebo when compared with those who received racemic albuterol. The difference was more evident and was statistically significant in patients who were not receiving inhaled corticosteroids. Conclusion: Levalbuterol appears to provide a better therapeutic index than the standard dose of racemic albuterol. These results support the concept that (S)-albuterol may have detrimental effects on pulmonary function. (J Allergy Clin Immunol 1998;102:943-52.)     

Comparison of inhaled salmeterol and oral zafirlukast in patients with asthma

BACKGROUND: Salmeterol, a long-acting beta2 -agonist, and zafirlukast, a leukotriene receptor antagonist, are both indicated for the treatment of asthma in adolescent and adult patients. OBJECTIVE: We sought to compare the effect of 4 weeks of treatment with inhaled salmeterol xinafoate versus oral zafirlukast in the treatment of persistent asthma. METHODS: This was a randomized, double-blind, double-dummy, parallel-group, multicenter clinical trial. Patients, over 80% of whom were on a concurrent inhaled corticosteroid regimen, were treated for 4 weeks with either inhaled salmeterol xinafoate 42 microgram twice daily administered by means of a metered-dose inhaler or oral zafirlukast 20 mg twice daily. The primary efficacy measure was morning peak expiratory flow (PEF); secondary efficacy measures included evening PEF, asthma symptom scores, supplemental albuterol use, nighttime awakenings, sleep symptoms, asthma exacerbations, and FEV1. RESULTS: Both inhaled salmeterol and oral zafirlukast resulted in within-group improvements from baseline in measures of pulmonary function, asthma symptoms, and supplemental albuterol use. Salmeterol treatment resulted in significantly greater improvements from baseline compared with zafirlukast for most efficacy measurements, including morning PEF (29.6 vs 13.0 L/min; P 相似文献   

Pharmacokinetics of prednisolone and its impact on cortisol kinetics in the blood serum of apparently healthy human subjects

Individual characteristics of prednisolone and cortisol pharmacokinetics in five young healthy subjects administered prednisolone in a single oral dose of 25 mg are described. The results suggests that prednisolone inhibits the glucocorticoid function of the adrenal cortex. It is concluded that the pharmacokinetics of prednisolone can be assessed from the reductions in serum cortisol concentration which it causes. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 122, No. 7, pp. 51–54, July, 1996     

Use of pharmacokinetic profile in evaluating patients with repeatedly low theophylline concentrations

Assessment of individual pharmacokinetics has been helpful in the evaluation of patients with persistently low serum theophylline concentrations and poorly controlled asthma. This paper presents seven cases where pharmacokinetic profiling specifically identified the etiology for low theophylline concentrations. Pharmacokinetic profiles were done following oral or intravenous dosing of theophylline. Serial blood samples drawn over 12 hours were assayed for theophylline concentrations using HPLC. Serum half-life (t1/2), clearance (Cl), volume of distribution (VD) and time-to-peak concentration were determined for each subject. In this series, three patients exhibited rapid theophylline clearance, two had predictable theophylline pharmacokinetics, and two presented with unique pharmacokinetics. These cases illustrate a wide range of pharmacokinetic behavior seen in clinical practice. To evaluate patients with persistently subtherapeutic theophylline concentrations, determination of individual pharmacokinetic profiles should be performed before prescribing high doses of theophylline (greater than 30 mg/kg/day).