Allergen-specific IgE as a biomarker of exposure plus sensitization in inner-city adolescents with asthma

BACKGROUND

Relationships among allergen-specific IgE levels, allergen exposure and asthma severity are poorly understood since sensitization has previously been evaluated as a dichotomous, rather than continuous characteristic.

METHODS

Five hundred and forty-six inner-city adolescents enrolled in the Asthma Control Evaluation study underwent exhaled nitric oxide (FE(NO)) measurement, lung function testing, and completion of a questionnaire. Allergen-specific IgE levels and blood eosinophils were quantified. Dust samples were collected from the participants' bedrooms for quantification of allergen concentrations. Participants were followed for 12 months and clinical outcomes were tracked.

RESULTS

Among sensitized participants, allergen-specific IgE levels were correlated with the corresponding settled dust allergen levels for cockroach, dust mite, and mouse (r = 0.38, 0.34, 0.19, respectively; P < 0.0001 for cockroach and dust mite and P = 0.03 for mouse), but not cat (r = -0.02, P = 0.71). Higher cockroach-, mite-, mouse-, and cat-specific IgE levels were associated with higher FE(NO) concentrations, poorer lung function, and higher blood eosinophils. Higher cat, dust mite, and mouse allergen-specific IgE levels were also associated with an increasing risk of exacerbations or hospitalization.

CONCLUSIONS

Allergen-specific IgE levels were correlated with allergen exposure among sensitized participants, except for cat. Allergen-specific IgE levels were also associated with more severe asthma across a range of clinical and biologic markers. Adjusting for exposure did not provide additional predictive value, suggesting that higher allergen-specific IgE levels may be indicative of both higher exposure and a greater degree of sensitization, which in turn may result in greater asthma severity.

Predicting worsening asthma control following the common cold

The asthmatic response to the common cold is highly variable, and early characteristics that predict worsening of asthma control following a cold have not been identified. In this prospective multicentric cohort study of 413 adult subjects with asthma, the mini-Asthma Control Questionnaire (mini-ACQ) was used to quantify changes in asthma control and the Wisconsin Upper Respiratory Symptom Survey-21 (WURSS-21) to measure cold severity. Univariate and multivariable models were used to examine demographic, physiological, serological and cold-related characteristics for their relationship to changes in asthma control following a cold. Clinically significant worsening of asthma control was observed following a cold (mean+/-SD increase in mini-ACQ score of 0.69+/-0.93). Univariate analysis demonstrated that season, centre location, cold duration and cold severity measurements were all associated with a change in asthma control. Multivariable analysis of the covariates available within the first 2 days of cold onset revealed that the day 2 and cumulative sum of day 1 and 2 WURSS-21 scores were significant predictors of the subsequent changes in asthma control. In asthmatic subjects, cold severity within the first 2 days can be used to predict subsequent changes in asthma control. This information may help clinicians prevent deterioration in asthma control following a cold.

Use of the modified Delphi technique to identify and rate home injury hazard risks and prevention methods for young children

OBJECTIVE

For children aged 1-5 years, the authors used the Delphi method to determine (1) the most important injury hazards in each area of the home; (2) the most important injury prevention behaviors; and (3) feasible and efficacious safety devices and behaviors to reduce injury risks.

DESIGN

The authors used a modified Delphi method to prioritize home injury hazards for children 1-5 years of age. The Delphi method is an indirect, anonymous, iterative process aimed at achieving consensus among experts; in this study, the authors queried key informants electronically. Thirty four key informants, primarily from the United States, participated in at least one of the three rounds of questionnaires. Responses were submitted by email or fax. Participants identified, rated, and ranked home injury hazards and prevention methods.

RESULTS

The overall response rate for each survey ranged from 82% to 97%. Initially, 330 unique hazards and prevention behaviors/devices were identified in seven areas of the home. The 126 home injury hazards were rated based on frequency, severity, and preventability of injury; and the 204 behaviors and devices were rated by efficacy and feasibility. These experts rated firearms and pools as the most significant hazards, and smoke alarms and safe water temperature as the most important preventions.

CONCLUSIONS

The modified Delphi method of consensus was useful to prioritize home injury hazards and prevention methods for children under the age of 6 years.

Validating self reported home safety practices in a culturally diverse non-inner city population

OBJECTIVE

To determine the validity of face to face, self reported responses to questions about the presence of safety devices and use of safety practices in the home aimed at preventing unintended injuries to preschool aged children.

METHODS

The authors invited families with children enrolling in a medium sized Midwestern US community Head Start program to participate in a randomized study of home safety practices. Participation involved consenting parents (n = 452) completing an initial questionnaire during Head Start enrollment or in their home. Project staff conducted home inspections to confirm parental responses to 16 questions. Only inspections conducted within 34 days of questionnaire completion (n = 259) were included in the validation study. Parents were told that the home visit would assess the need for safety devices, but were not informed of the validation aspect of the study.

RESULTS

Sensitivities were generally high for all 16 safety practices, whereas negative predictive value and specificity varied considerably. Positive predictive value was also high for most practices, and did not vary by ethnicity. Answers provided by parents in their home were different and more reliable than those provided by parents interviewed at school (p = 0.001).

CONCLUSIONS

Use of safety devices and practices by parents of preschool aged children reported in a face to face interview are generally reliable. Reliability increases if the interview is conducted in the home. Parents may also be more willing to report potential problems if they perceive they may receive corrective assistance.

Recruitment strategies in the Asthma Clinical Research Network

In any clinical trial, recruitment of trial participants usually requires an intense effort to reach the target sample size. The Asthma Clinical Research Network (ACRN) was keenly aware of this issue at its inception and therefore initiated and emphasized recruitment strategies for each of its clinical trials. This article describes the recruitment strategies for the ACRN's first four major clinical trials. Particular attention is given to the strategies for the recruitment of women and minorities. Finally, the specific strategies of each of the six ACRN clinical centers are presented.

Inhaled corticosteroid reduction and elimination in patients with persistent asthma receiving salmeterol: a randomized controlled trial

CONTEXT

Inhaled long-acting beta(2)-agonists improve asthma control when added to inhaled corticosteroid (ICS) therapy.

OBJECTIVE

To determine whether ICS therapy can be reduced or eliminated in patients with persistent asthma after adding a long-acting beta(2)-agonist to their treatment regimen.

DESIGN AND SETTING

A 24-week randomized, controlled, blinded, double-dummy, parallel-group trial conducted at 6 National Institutes of Health-sponsored, university-based ambulatory care centers from February 1997 through January 1999.

PARTICIPANTS

One hundred seventy-five patients aged 12 through 65 years with persistent asthma that was suboptimally controlled during a 6-week run-in period of treatment with inhaled triamcinolone acetonide (400 microg twice per day).

INTERVENTION

Patients continued triamcinolone therapy and were randomly assigned to receive add-on therapy with either placebo (placebo-minus group, n = 21) or salmeterol xinafoate, 42 microg twice per day (n = 154) for 2 weeks. The entire placebo-minus group was assigned and half of the salmeterol group (salmeterol-minus group) was randomly assigned to reduce by 50% (for 8 weeks) then eliminate (for 8 weeks) triamcinolone treatment. The other half of the salmeterol group (salmeterol-plus group) was randomly assigned to continue both salmeterol and triamcinolone for the remaining 16 weeks (active control group).

MAIN OUTCOME MEASURE

Time to asthma treatment failure in patients receiving salmeterol.

RESULTS

Treatment failure occurred in 8.3% (95% confidence interval [CI], 2%-15%) of the salmeterol-minus group 8 weeks after triamcinolone treatment was reduced compared with 2.8% (95% CI, 0%-7%) of the salmeterol-plus group during the same period. Treatment failure occurred in 46.3% (95% CI, 34%-59%) of the salmeterol-minus group 8 weeks after triamcinolone therapy was eliminated compared with 13.7% (95% CI, 5%-22%) of the salmeterol-plus group. The relative risk (95% CI) of treatment failure at the end of the triamcinolone elimination phase in the salmeterol-minus group was 4.3 (2.0-9.2) compared with the salmeterol-plus group (P<.001).

CONCLUSIONS

Our results indicate that in patients with persistent asthma suboptimally controlled by triamcinolone therapy alone but whose asthma symptoms improve after addition of salmeterol, a substantial reduction (50%) in triamcinolone dose can occur without a significant loss of asthma control. However, total elimination of triamcinolone therapy results in a significant deterioration in asthma control and, therefore, cannot be recommended.

Long-acting beta2-agonist monotherapy vs continued therapy with inhaled corticosteroids in patients with persistent asthma: a randomized controlled trial

CONTEXT

Long-acting beta(2)-agonists are prescribed for patients with persistent asthma and are sometimes used without inhaled corticosteroids (ICSs). No evidence exists, however, to support their use as monotherapy in adults with persistent asthma.

OBJECTIVE

To examine the effectiveness of salmeterol xinafoate, a long-acting beta(2)-agonist, as replacement therapy in patients whose asthma is well controlled by low-dose triamcinolone acetonide, an ICS.

DESIGN AND SETTING

A 28-week, randomized, blinded, placebo-controlled, parallel group trial conducted at 6 National Institutes of Health-sponsored, university-based ambulatory care centers from February 1997 to January 1999.

PARTICIPANTS

One hundred sixty-four patients aged 12 through 65 years with persistent asthma that was well controlled during a 6-week run-in period of treatment with inhaled triamcinolone (400 microg twice per day).

INTERVENTIONS

Patients were randomly assigned to continue triamcinolone therapy (400 microg twice per day; n = 54) or switch to salmeterol (42 microg twice per day; n = 54) or to placebo (n = 56) for 16 weeks, after which all patients received placebo for an additional 6-week run-out period.

MAIN OUTCOME MEASURES

Change in morning and evening peak expiratory flow (PEF), forced expiratory volume in 1 second (FEV(1)), self-assessed asthma symptom scores, rescue albuterol use, asthma-specific quality-of-life scores, treatment failure, asthma exacerbation, bronchial reactivity, and markers of airway inflammation, compared among the 3 treatment groups.

RESULTS

During the 16-week randomized treatment period, no significant differences between the salmeterol and triamcinolone groups were observed for conventional outcomes of clinical studies of asthma therapy-morning PEF, evening PEF, asthma symptom scores, rescue albuterol sulfate use, or quality of life. Both active treatments were superior to placebo. However, the salmeterol group had more treatment failures than the triamcinolone group (13/54 [24%] vs 3/54 [6%]; P =.004), as well as more asthma exacerbations (11/54 [20%] vs 4/54 [7%]; P =.04), greater increases in median (interquartile range) sputum eosinophils (2.4% [0.0% to 10.6%] vs -0.1% [-0.7% to 0.3%]; P<.001), eosinophil cationic protein (71 [-2 to 430] U/L vs -4 [-31 to 56] U/L; P =.005), and tryptase (3.1 [2.1 to 7.6] ng/mL vs 0.0 [0.0 to 0.7] ng/mL; P<.001). The duration of benefit when patients were switched from active treatment to placebo after 22 weeks of randomized treatment was not significantly longer in the triamcinolone group than in the salmeterol group.

CONCLUSIONS

Patients with persistent asthma well controlled by low doses of triamcinolone cannot be switched to salmeterol monotherapy without risk of clinically significant loss of asthma control.

Leukotriene receptor antagonists in the treatment of asthma

The role of leukotriene receptor antagonists in the treatment of persistent asthma is in evolution. Pivotal 8-12-week, randomized, controlled trials in both adults and children have shown efficacy, as defined by standard asthma outcomes. Tolerance to therapy did not develop, nor did rebound worsening of asthma symptoms once therapy was withdrawn. In a comparator trial of montelukast versus beclomethasone, the average percentage change from baseline in forced expiratory volume in 1 second was greater with the inhaled corticosteroid preparation; however, improvements in other asthma outcomes were similar. There was considerable heterogeneity of pulmonary response with both treatments, with good and poor responders in both groups. In an open-label, crossover comparison of montelukast versus cromolyn, both parents and children preferred montelukast, thus regimen adherence was greater with montelukast. Additional long-term, randomized, controlled trials will define the effectiveness of leukotriene receptor antagonists compared with established controllers, thus determining the leukotriene receptor antagonists' place in asthma management.

Effect of polymorphism of the beta(2)-adrenergic receptor on response to regular use of albuterol in asthma

BACKGROUND

Regular use of inhaled beta-adrenergic agonists may have adverse effects in some asthma patients. Polymorphisms of the beta(2)-adrenergic receptor (beta(2)-AR) can affect its regulation; however, results of smaller studies of the effects of such polymorphisms on response to beta-agonist therapy have been inconsistent.

METHODS

We examined the possible effects of polymorphisms at codons 16 (beta(2)-AR-16) and 27 (beta(2)-AR-27) on response to albuterol by genotyping 190 asthmatics who had participated in a trial of regular versus as-needed albuterol use.

RESULTS

During the 16-week treatment period, patients homozygous for arginine (Arg/Arg) at beta(2)-AR-16 who used albuterol regularly had a small decline in morning peak expiratory flow (AM PEF). This effect was magnified during a 4-week run-out period, when all patients returned to as-needed albuterol only. By the end of the study, Arg/Arg subjects who had used albuterol regularly had an AM PEF 30.5 +/- 12.1 liters/min lower (p = 0.012) than Arg/Arg patients who had used albuterol as needed only. Subjects homozygous for glycine at beta(2)-AR-16 showed no such decline. Evening PEF also declined in the Arg/Arg regular but not in as-need albuterol users. No significant differences between regular and as-needed treatment were associated with polymorphisms at beta(2)-AR-27.

CONCLUSIONS

Polymorphisms of the beta(2)-AR may influence airway responses to regular inhaled beta-agonist treatment.

Fluticasone propionate: a potent inhaled corticosteroid for the treatment of asthma

Fluticasone propionate (FP) is a potent inhaled corticosteroid (ICS) for the treatment of asthma. It is currently marketed in both the United States (as Flovent) and Europe (as Flixotide). Fluticasone is available in both aerosolised metered dose inhaler (MDI) and dry powder devices, with dosages ranging from 44-500 micrograms/puff. FP has been extensively studied in both children and adults; efficacy has been documented across the entire spectrum of asthma severity, including corticosteroid-dependent disease. Clinical data with FP strongly corroborates the in vitro pharmacokinetic and pharmacodynamic studies that FP is at least twice as potent as beclomethasone dipropionate (BDP), budesonide (BUD) or triamcinolone acetonide (TAA). Both objective (lung function) and subjective (symptoms, beta-agonist use and quality of life) outcomes are improved with FP treatment. Extensive post-marketing surveillance with FP suggests that it is more cost-effective than BUD and flunisolide (FLU) when analysed by an overall healthcare cost perspective. Most of the benefits arise from decreased hospitalizations, emergency room visits and physician-office visits. Extensive safety data with FP documents no clinically meaningful effects on bone mass, nor impairment of growth velocity in children. Considering the efficacy and safety data along with the ability to optimise patient's asthma therapy using the delivery devices and strengths available, FP has become a leader in the ICS marketplace to date.

The effect of polymorphisms of the beta(2)-adrenergic receptor on the response to regular use of albuterol in asthma

Inhaled beta-adrenergic agonists are the most commonly used medications for the treatment of asthma although there is evidence that regular use may produce adverse effects in some patients. Polymorphisms of the beta(2)-adrenergic receptor (beta(2)-AR) can affect regulation of the receptor. Smaller studies examining the effects of such polymorphisms on the response to beta-agonist therapy have produced inconsistent results. We examined whether polymorphisms at codon 16 (beta(2)-AR-16) and codon 27 (beta(2)-AR-27) of the beta(2)-AR might affect the response to regular versus as-needed use of albuterol by genotyping the 190 asthmatics who had participated in a trial examining the effects of regular versus as needed albuterol use. During the 16-wk treatment period there was a small decline in morning peak expiratory flow in patients homozygous for arginine at B(2)-AR-16 (Arg/Arg) who used albuterol regularly. This effect was magnified during a 4-wk run out period, during which all patients returned to using as-needed albuterol, so that by the end of the study Arg Arg patients who had regularly used albuterol had a morning peak expiratory flow 30. 5 +/- 12.1 L/min lower (p = 0.012) than Arg/Arg patients who had used albuterol on an as needed basis. There was no decline in peak flow with regular use of albuterol in patients who were homozygous for glycine at beta(2)-AR-16. Evening peak expiratory flow also declined in the Arg/Arg patients who used albuterol regularly but not in those who used albuterol on an as-needed basis. No significant differences in outcomes between regular and as-needed treatment were associated with polymorphisms at position 27 of the beta(2)-AR. No other differences in asthma outcomes that we investigated occurred in relation to these beta(2)-AR polymorphisms. Polymorphisms of the beta(2)-AR may influence airway responses to regular inhaled beta-agonist treatment.

Effects of the inhaled corticosteroids fluticasone propionate, triamcinolone acetonide, and flunisolide and oral prednisone on the hypothalamic-pituitary-adrenal axis in adult patients with asthma

Two multicenter, randomized, double-masked, placebo-controlled, parallel-group studies were conducted in adult patients with mild-to-moderate persistent asthma to assess the effects of 4 weeks of treatment with inhaled corticosteroids on hypothalamic-pituitary-adrenal (HPA) axis function. The first study compared fluticasone propionate 100 and 500 microg twice daily, triamcinolone acetonide 300 and 500 microg twice daily, oral prednisone 10 mg every morning, and placebo. The second study compared fluticasone propionate 100 and 250 microg twice daily, flunisolide 500 microg twice daily, and placebo. Therapeutic doses of fluticasone propionate, triamcinolone acetonide, and flunisolide were found to be comparable to each other and to placebo in their lack of adrenal suppressive effects, based on mean plasma cortisol responses to 6-hour cosyntropin infusion. Prednisone produced significantly greater suppression of HPA-axis function than did any of the inhaled corticosteroids or placebo (P<0.001). Mean reductions from baseline in 8-hour area under the plasma concentration-time curve (AUC) and 8-hour peak plasma cortisol concentrations and the mean percentage of change from baseline in 8-hour AUC were significantly greater after treatment with triamcinolone acetonide 500 microg twice daily compared with placebo (P< or =0.042). These findings indicate that fluticasone propionate has no greater systemic effect than either triamcinolone acetonide or flunisolide at doses appropriate for patients with mild-to-moderate persistent asthma.

Establishing a therapeutic index for the inhaled corticosteroids: part II. Comparisons of systemic activity and safety among different inhaled corticosteroids

The systemic activity and safety of inhaled corticosteroids are best studied in randomized, controlled, long-term trials with clinically relevant doses in subjects. These studies require large numbers of enrolled subjects and are difficult to conduct. Potential confounders to safety analyses must be controlled. The occurrence and magnitude of adrenal suppression has been the most extensively evaluated systemic effect of inhaled corticosteroids. The significance of these findings in relation to relevant clinical outcomes must be evaluated. At low to medium inhaled corticosteroid dosages, the hypothalamic-pituitary-adrenal axis is minimally and only partially suppressed. Statistically significant changes occur at high inhaled corticosteroid dosages; the magnitude of this effect is less than with prednisone, > or = 10 mg/day. Standards for the design of growth studies in children with asthma have been recommended and recently implemented. Four randomized, controlled, clinical trials have reported reductions in growth rates of > 1 cm/yr with beclomethasone < or = 400 microg/day. By comparison, 2 randomized controlled clinical trials with fluticasone, 50 to 100 microg twice daily via dry powder inhaler, could not detect differences in height velocity in prepubertal children treated with cromolyn sodium or placebo. Trials with low to medium doses of beclomethasone, fluticasone, and budesonide document little to no effect on bone mineral density and bone metabolism. Population-based and limited randomized controlled trials suggest that low to medium doses of inhaled corticosteroids do not cause cataracts or glaucoma. Patients requiring high-dose inhaled corticosteroids should be monitored for adverse effects, with appropriate lifestyle changes and pharmacologic strategies implemented.

Asthma in non-inner city Head Start children

OBJECTIVE

Asthma is a significant cause of morbidity and mortality in children. The objective of this study was to determine whether the federal program Head Start in Dane County, Wisconsin, could be used as a mechanism to identify preschool-aged children with asthma.

DESIGN

Five-year, cross-sectional survey of parents with children enrolled in Head Start.

METHODS

Investigator-administered asthma screening questionnaire to parents of enrolling Head Start children in Dane County, Wisconsin.

MEASUREMENTS

Asthma prevalence and asthma-related health care use, including emergency department visits, hospitalizations, and medication usage, were measured using an asthma screening questionnaire developed by investigators.

RESULTS

Information was gathered on 2215 children. The prevalence of physician-diagnosed asthma in the screened children was 15.8%. Parental reports of physician-diagnosed asthma were validated in a subset of 133 children, with a 98.5% confirmation rate. Independent risk factors for asthma included male gender (relative risk, 1.4) and African-American ethnicity (relative risk, 1.4). Asthma-related morbidity was substantial with 26.7% of identified children hospitalized for asthma and 54.5% with an emergency department visit during their lifetime. The majority of children (46.4%) were treated with intermittent, quick relief medications (beta-agonists) alone, whereas only 6.1% were on daily, long-term controller medications.

CONCLUSIONS

Asthma screening through a Head Start program provides an effective means of targeting preschool-aged children from socioeconomic groups at high risk for asthma. Identification of children early in the disease course and those at high risk for asthma provides an ideal opportunity for the implementation of preventive and therapeutic interventions.

The use of 5-lipoxygenase inhibitors and leukotriene receptor antagonists in the treatment of chronic asthma

With the elucidation of asthma as a chronic inflammatory disease, therapeutic approaches have shifted from treatment of symptoms with bronchodilators to treatment of the underlying disease with antiinflammatory agents. Along with concerns about corticosteroid side effects on the part of both physicians and patients, this shift has motivated researchers to develop and test new agents with antiinflammatory capabilities. The leukotrienes are endogenous mediators with three inflammatory effects: they increase vascular permeability, recruit other inflammatory leukocytes, and induce bronchoconstriction. A number of antileukotriene agents are in various stages of development. Zileuton, a leukotriene synthesis inhibitor, has been shown to improve airway function and reduce asthma-symptoms, although there is some concern over liver toxicity. Zafirlukast, montelukast, and pranlukast, three new leukotriene receptor antagonists, have similar benefits and have not been associated with serious increases in liver enzymes. It is hoped that new antiinflammatory drugs will provide clinicians with targeted and effective asthma treatments that do not bear the potential risks of corticosteroid therapy.

Effects of montelukast (MK-0476); a potent cysteinyl leukotriene receptor antagonist, on bronchodilation in asthmatic subjects treated with and without inhaled corticosteroids

BACKGROUND

Cysteinyl leukotriene release in association with airway inflammation is a feature of clinical asthma. The acute effects of montelukast (MK-0476), a potent, orally administered, specific cysteinyl leukotriene receptor antagonist, on airways obstruction was assessed in patients with mild to moderately severe asthma.

METHODS

Twenty two asthmatic subjects were randomised to receive montelukast, 100 mg or 250 mg, or placebo in a double blind, three period, crossover trial. Ten of the patients were using concomitant inhaled corticosteroids.

RESULTS

Montelukast increased the forced expiratory volume in one second (FEV1) from predose baseline values compared with placebo, the percentage point differences between montelukast and placebo being 8.6% (95% CI 3.6 to 13.6) and 8.5% (95% CI 3.5 to 13.5) for the 100 mg and 250 mg doses, respectively.

CONCLUSION

Single oral doses of montelukast 100 mg and 250 mg produced significant increases in FEV1 irrespective of the concurrent use of inhaled corticosteroids in asthmatic subjects with airflow limitation.

Potential interaction between warfarin and dicloxacillin

OBJECTIVE

To report a case and retrospective review of seven patients who experienced a decrease in prothrombin time during concomitant administration of warfarin and dicloxacillin.

CASE SUMMARY

A 41-year-old man receiving warfarin 22 mg/wk with a final baseline prothrombin time (PT) of 20.7 sec was prescribed dicloxacillin 500 mg qid for 10 days. Plasma collected for PT determinations was also used to measure trough warfarin R- and S- enantiomer concentrations. The PT and S- and R-warfarin concentrations decreased 17%, 25%, and 20%, respectively, on day 5 after initiation of dicloxacillin. For the retrospective review, the mean PT decreased 17.0% (range 10.5-25.9%) as soon as 4 days after the initiation of dicloxacillin.

DISCUSSION

Our observations, which are consistent with those of two previously published reports, suggest a close temporal relationship between the administration of dicloxacillin and a decreased anticoagulant effect of warfarin. Limited data from our patient further suggest that this may result from declines in systemic warfarin concentrations. The time course of the fall of PTs appears to occur within 4-5 days; return of the PT to baseline after dicloxacillin administration is stopped appears to take up to 3 weeks. Until further controlled studies are conducted to confirm this interaction, clinicians should be aware that patients may be at risk for a decreased anticoagulant effect of warfarin when dicloxacillin is given concomitantly.

CONCLUSIONS

Careful monitoring of international normalized ratios and titration of the warfarin dosage is recommended on initiation and for 3 weeks after discontinuation of dicloxacillin in patients receiving warfarin.

Evaluation of a potential enantioselective interaction between ticlopidine and warfarin in chronically anticoagulated patients

Ticlopidine is a novel antiplatelet drug reported to cause significant inhibition of several drugs metabolized by the hepatic cytochrome P-450 enzyme system, including antipyrine and theophylline. Warfarin, a racemic mixture of two enantiomers (R and S), is extensively metabolized by the CYP-450 system. S-Warfarin is five to eight times as active as R-warfarin. The effects of ticlopidine on the pharmacokinetics and pharmacodynamics of warfarin were examined in nine elderly men (69 +/- 4 years) receiving long-term warfarin therapy. Steady-state warfarin enantiomer concentrations and International Normalized Ratios (INRs) were determined at baseline and after 14 days of treatment with oral ticlopidine, 250 mg twice daily. Warfarin enantiomer serum concentrations were determined by high-performance liquid chromatography after chiral derivitization. Ticlopidine co-medication resulted in a significant increase in mean R-warfarin concentrations (+25.7%, p < 0.05), while no significant difference in S-warfarin concentrations was noted (+0.8%). Mean INR values were not significantly different from the baseline (+8.3%), although substantial interindividual variability was noted. We conclude that ticlopidine co-medication does result in an enantioselective kinetic interaction with warfarin; however, this interaction is likely to be of minimal clinical significance in most patients.

Outcome assessment of pain: functional status measures and quality of life as therapeutic endpoints

These studies and others will provide tools for cancer treatment centers to integrate pain management into comprehensive care strategies. Pharmacists in all health care settings where the cancer patient with pain is being treated should take leadership roles in the improvement of therapeutic outcomes. This leadership is essential, because drug therapy remains the mainstay of palliation.

Use of serum drug concentrations in outpatient clinics

A four-month retrospective study was conducted to analyze the use of serum drug concentrations (SDCs) in the outpatient clinics of a teaching hospital. The general internal medicine, asthma and allergy, cardiology, and neurology clinics were selected as frequent users of SDCs. Serum theophylline, digoxin, quinidine, procainamide, carbamazepine, phenytoin, and phenobarbital concentrations obtained during patient clinic visits were audited by trained pharmacy students using medical records and computer-generated laboratory data. The SDCs were evaluated for (1) the appropriateness of how they were obtained, (2) the appropriateness of the actions taken on the results, (3) the reasons they were ordered, and (4) the patient charges secondary to obtaining SDCs incorrectly or taking inappropriate actions on the results. Overall, the SDCs from all the clinics combined were obtained appropriately 251 (61.4%) of 409 times. Appropriate actions were taken on the SDC results 82.4% of the time. A change in therapy was made after an SDC was ordered 24.4% of the time. A total of $4975 of patient charges was associated with incorrectly obtained SDCs or inappropriate actions taken on SDC results. The asthma and allergy clinic, which was staffed by a clinical pharmacist, used SDCs more appropriately than the other clinics. Pharmacists or other professionals should be used to obtain accurate SDC information and to follow-up on SDC results to maximize drug therapy and reduce costs.