630 Thorax 1990;45:630-632 Effect of caffeine on histamine bronchoprovocation in asthma Thorax: first published as 10.1136/thx.45.8.630 on 1 August 1990. Downloaded from Antoinette Colacone, Luisa Bertolo, Norman Wolkove, Carol Cohen, Harvey Kreisman Abstract nosis of asthma sometimes include testing for It was recently reported that caffeine bronchial hyperreactivity to specific or non- may reduce the clinical symptoms of specific stimuli. Histamine broncho- asthma and may prevent the clinical provocation challenge is often used to measure manifestations of this disease. The effect non-specific airway reactivity in the of caffeine on histamine responsiveness laboratory or in population surveys.2 Anti- is unknown. The effect of caffeine (5 mg/ asthmatic medication, including theophylline, kg) and placebo on histamine respon- may attenuate the bronchoconstriction siveness (the provocation concentration induced by histamine and specific recommen- causing a 20% fall in FEVy, PC20) was dations exist for withholding these medica- studied in 10 subjects with mild asthma tions before bronchoprovocation testing.-4 (prechallenge FEV, 84% of predicted There are no specific guidelines, however, for value). The PC20 for histamine caffeine intake before testing. bronchoprovocation after caffeine inges- The purpose of this investigation was to tion was 2 65 (95% confidence limits 0 99, study whether caffeine at a dose of 5 mg/kg 7-10) mg/ml. After placebo the PC20 was (about 3 cups of coffee) would alter histamine 189 (0-96, 3-71) mg/ml. It is concluded reactivity in adults with mild bronchial that caffeine in a dose equivalent to asthma. We chose this dose because the about three cups of coffee has a very average caffeine content in a cup of coffee is small effect, if any, on histamine about 150 mg and only 1900 of the population bronchoprovocation in those with mild have more than three cups a day.' 8 asthma. Specific instructions about not having drinks containing caffeine before are not histamine challenge therefore Methods http://thorax.bmj.com/ necessary. SUBJECTS We studied 10 symptom free asthmatic subjects (seven male) with a mean age of 46 An inverse correlation between coffee intake (SD 17) years. Nine subjects had previously and the prevalence of asthma was reported documented increased airway reactivity (a recently.' The risk of asthma was 20% less in provocative concentration of histamine caus- those who consumed two or more cups a day ing a 20% fall in FEV, (PC20) less than 8 mg/ than in those who drank none. The broncho- ml), and the other had a history of seasonal on September 25, 2021 by guest. Protected copyright. dilator effect of caffeine may reduce the clin- asthma and a PC20 of less than 16 mg/ml. ical symptoms of asthma or prevent the clin- Before the study seven subjects used an ical manifestations of the disease.' Asthma inhaled beta agonist, five theophylline and may be underdiagnosed therefore in a coffee four an inhaled corticosteroid; two required consuming population. no medication. The four patients taking Current guidelines for the laboratory diag- inhaled steroids (Nos 2, 5, 7, 8 in the table) Pulmonary Division, Individual caffeine doses, serum concentrations, and their effect on bronchial responsiveness to histamine (PC20) Department of Medicine, Sir Serum caffeine PC20 (mg/ml) %AFEV, slope (mg/ml) Mortimer B Davis- Caffeine concentration Jewish General Patient No Weight (kg) dose (mg) (,g/ml) Placebo Caffeine Placebo Caffeine Hospital, Mount Sinai Hospital and McGill 1 73 365 2-5 0-6 4 1-7 3-0 University, Montreal, 2 95-5 477 4-5 1-4 0-4 3-6 3-0 Quebec, Canada 3 110 550 6-7 2-3 16 17-8 47-2 A Colacone 4 70 350 5-4 6 11 10-2 0-5 L Bertolo 5 84-5 425 6-0 0-6 0-6 3-6 1-8 N Wolkove 6 57-5 289 6-5 2-5 2-2 38-6 41-4 C Cohen 7 107 535 5-7 1-5 1-5 8-7 14-3 H Kreisman 8 65 325 5-7 6 8-8 2-6 2-2 Address for reprint requests: 9 71 355 63 0-7 0-6 11-0 9-1 Dr Harvey Kreisman, c/o 10 76 380 4-7 5-8 6-8 12-2 16-5 Pulmonary Division, Sir 81 405-1 5-4 Mortimer B Davis-Jewish Mean 1.9*t 2.7*t 7.4*t 6-1*1 General Hospital, 3755 Cote SD 17-8 88-9 1-2 (1-0,3-7) (1-0,7-1) (2-1,17-5) (3-7,14-7) St Catherine Road, Montreal, Quebec, Canada *Geometric means with 95% confidence intervals in parentheses. H3T 1E2. tP = 0-31 in the comparison of PC2. after placebo and after caffeine. Accepted 3 April 1990 $p = 0-61 in the comparison of slope after placebo and after caffeine. Effiect of caffeine on histamine bronchoprovocation in asthma 631 Figure 1 Identity plot FEV1 (1) the same time of day on two days within two showing prechallenge placebo weeks. FEV, (I) of individual 12oar^,r, 'aA.o.bones-.a-rRy nolr,= +^ subjects on the two study 5 ;Viore eac1s-ELUUy SUUJDiecLi We1r as^eU LU days. Mean (SD) FEV, Mean (SD) refrain from consuming products containing Thorax: first published as 10.1136/thx.45.8.630 on 1 August 1990. Downloaded from caffeine 2 65 (0 73) 1, caffeine for 48 hours and to fast for eight placebo 2 67 (0 78) 1. Caffeine 2/65(0.73) * 4 Caffeine 2.65 (0.73) hours. Antiasthmatic medications were with- Placebo 2.67 (0.78) held according to standard guidelines for his- tamine bronchoprovocation testing.4 Beta 3 agonists and anticholinergic drugs were with- 0. held for 8-12 hours and theophylline for 24 hours before testing. Slow release theo- phylline and antihistamines were not con- 2 sumed for 48 hours before testing. Steroids were continued as usual. Spirometry was performed with a recording 1 spirometer (Vitalograph, Model S, Kansas City, Missouri). Baseline spirometric tests were carried out in triplicate and the FEVy C was recorded from the best spirogram (sum of 0 1 2 3 4 5 FEVy and forced vital capacity). Subjects then FEV, (1) caffeine ingested either caffeine (5 mg/kg body weight) in aqueous solution or an equivalent volume of placebo. tooik the same doses before and during the Blood for serum caffeine and theophylline stuidy. determination was drawn 105 minutes after StIrhe protocol was approved by the ethics ingestion of the test medication. The blood connmittee of the Sir Mortimer B Davis-Jew- samples were then centrifuged and stored at ish General Hospital. Informed consent was -20°C. Caffeine and theophylline concentra- obtained from each subject. tions were later determined by high pressure liquid chromatography.5 TEST MEDICATIONS Spirometry was repeated two hours after Calffeine and corresponding placebo were ingestion and followed by a histamine prepared in solution and coded by the hospital challenge test performed according to the phairmacy. The former contained caffeine method of Cockcroft et al.6 A Wright nebul- citr-ate in a concentration of 50 mg/ml. Both iser was filled with 3 ml of solution and soliations contained amaranta colorant and operated at a flow of 9 1/min 50 lb/in2. The vantilla essence diluted with distilled water and nebuliser output had been calibrated to http://thorax.bmj.com/ werre indistinguishable by taste, colour, and deliver a mean of 0-26 (SD 0 008) ml over two smcell. minutes. Increasing doses of histamine were given until a 20% fall in FEVy had occurred. STUDY PROTOCOL STATISTICAL ANALYSIS The subjects were randomised to receive caf- Arithmetic means and standard deviations feine and placebo first in a double blind were computed for FEV,. PC20 values were crossover study. The study was carried out at log transformed before analysis; geometric on September 25, 2021 by guest. Protected copyright. mean values and 95% confidence intervals are given. The slope of the histamine dose-res- Figure 2 Bronchial ponse curve was calculated by linear regres- responsiveness to histamine 100 (PC20, mg/ml) on caffeine sion and log transformed before analysis by and placebo days. Two paired t test. Student's paired t test was used subjects had a two to compare differences between placebo and concentration increase in PC20 and another had a caffeine data. A p value below 0 05 was con- similar reduction in PC20 sidered statistically significant. on the day. placebo 10 - _ Results - Mean (SD) FEVy values before histamine C challenge did not differ significantly on the 0 *,v caffeine and placebo days (2-65 (0 73) and 2-67 I, v(0 78) litres; fig 1); both values were 84% ofthe PL4 I1 predicted FEVy.7 Mean (SD) FEVy increased by 0 10 (0 09) 1 after caffeine compared with 0 05 (0 06) after placebo (p = 0 38). The mean (SD) serum caffeine concentration was 5-4 ((1 -23) Mg/ml after caffeine; none was detected after placebo (table). Theophylline was not detected in the serum of any patient on either .1 I study day. All subjects had a of 16 or less Placebo Caffeine after both caffeine andPC20placebo. mg/mlThere was no 632 Colacone, Bertolo, Wolkove, Cohen, Kreisman significant difference in PC20 values or in the study were lower than expected from a dose of slope of the dose-response relationship be- 5 mg/kg caffeine.814 A given dose of caffeine, tween caffeine and placebo (table and fig 1). like theophylline, may produce a wide range of The PC20 increased by more than two dose serum concentrations in different individuals.