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Query: UMLS:C0010200 (cough)
 23,843 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have evaluated the properties of capsaicin as a selective cough-inducing agent in healthy human subjects. Despite frequent coughing, the subjects could inhale repeated breaths of capsaicin aerosol during 60 s without difficulty. Cough started immediately on inhalation and was most intense during the first 30 s. Cough always disappeared promptly when the capsaicin inhalation was terminated. The cough response was well reproducible and concentration-dependent up to 10 microM; at higher concentrations there was a distinct plateau of the cough response. Specific airway conductance was not changed 3 min after 50 microM capsaicin. Capsaicin (> or = 10 microM) had a burning taste, but there were no visual signs of pharyngitis or laryngitis. Citric acid (nebulized solutions 0.125 to 32%) had a choking effect and could be administered only as single breaths. There was no correlation between the cough response to citric acid and to capsaicin. Inhaled lidocaine (20 and 80 mg from nebulized solutions) caused a dose-dependent inhibition of capsaicin-induced cough. Lidocaine suppressed citric acid-induced cough as effectively as capsaicin-induced cough. In conclusion, we have characterized capsaicin-induced cough and demonstrated that it can be a useful tool in the study of cough reactivity and for evaluation of antitussive agents in humans. Capsaicin may be complementary to citric acid and may offer experimental advantages over this traditional tussive stimulus.
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PMID:Capsaicin-induced cough in humans. 148 23

Cough is a common respiratory symptom, the mechanism of which is poorly understood. In this study the role of 5-HT3 receptors was investigated. Capsaicin-induced cough and increase in airways resistance were measured in six male volunteers before and after infusion with granisetron 160 micrograms kg-1 or placebo. Neither cough nor the increase in respiratory resistance was altered by the active treatment. These results suggest that 5-HT3 receptors are not involved in these two respiratory responses to inhaled capsaicin in humans.
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PMID:Human responses to inhaled capsaicin are not inhibited by granisetron. 164 94

1. Twelve non-smoking subjects inhaled capsaicin at three different inspiratory flow rates: 50, 100 and 150 litres/min. Capsaicin was delivered by a breath-actuated dosimeter; inhalations consisted of 0.21-13.6 nmol of capsaicin in doubling amounts given in random order. 2. The mean number of coughs per challenge decreased with increasing inspiratory flow rate. The difference in cough numbers were significant: 7.7 (95% confidence interval 2.5-12.8) for 50 versus 100 litres/min and 10.9 (95% confidence interval 5.0-16.9) for 100 versus 150 litres/min. 3. On a separate day, a cough threshold was measured by giving increasing doses of citric acid that were inhaled at 50 litres/min. There was a positive correlation between the sensitivity to capsaicin and the cough threshold to citric acid (r = 0.69, P = 0.01), and also between the cough latencies (r = 0.67, P = 0.02). 4. The negative relationship between the cough response and the inspiratory flow rate may be caused by increased laryngeal deposition at lower inspiratory flow rates. 5. These results are compatible with a similar anatomical distribution of cough receptors for capsaicin and citric acid. 6. These results suggest that changes in inspiratory flow rate may affect the results of cough challenges.
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PMID:Effect of changes in inspiratory flow rate on cough responses to inhaled capsaicin. 165 2

A multicenter study was conducted to establish the efficacy of topical 0.075% capsaicin cream in relieving the pain associated with diabetic neuropathy. Capsaicin or vehicle cream was applied to painful areas four times per day for 8 weeks in patients randomly assigned to one of two groups. Pain intensity and relief were recorded at 2-week intervals using physician's global evaluation and visual analog scales. Analysis at final visit for 252 patients showed statistical significance favoring capsaicin compared with vehicle for the following: 69.5% vs 53.4% pain improvement by the physician's global evaluation scale, 38.1% vs 27.4% decrease in pain intensity, and 58.4% vs 45.3% improvement in pain relief. With the exception of transient burning, sneezing, and coughing, capsaicin was well tolerated. Study results suggest that topical capsaicin cream is safe and effective in treating painful diabetic neuropathy.
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PMID:Treatment of painful diabetic neuropathy with topical capsaicin. A multicenter, double-blind, vehicle-controlled study. The Capsaicin Study Group. 195 27

Inhaled furosemide prevents bronchoconstriction induced by nebulized distilled water, exercise, and antigen challenge. We examined the effect of furosemide on cough induced by low chloride content solutions and by capsaicin in double-blind, placebo-controlled studies. A group of eight nonsmoking normal subjects was given furosemide (3.75 mg/ml inhaled for 8 min) and placebo (saline) immediately before consecutive 1-min inhalations of four isosmolar solutions with decreasing chloride content every 5 min from an ultrasonic nebulizer. Decreasing concentrations of chloride induced dose-related coughing, which was inhibited by furosemide. Thus, chloride-free solution induced 13.1 +/- 1.6 coughs after placebo and 8.4 +/- 1.9 coughs after furosemide (p less than 0.005). In a separate study, six of the same normal subjects were given inhaled furosemide or placebo before inhaling one breath of capsaicin solution given in three consecutive increasing concentrations. Capsaicin induced dose-related coughing, which was not inhibited by furosemide. Thus, after placebo the highest concentration of capsaicin induced 20.8 +/- 1.8 coughs and after furosemide, 21.5 +/- 2.7 coughs. We conclude that furosemide may act by inhibiting the cough reflex indirectly, perhaps by changing local chloride ions within the vicinity of epithelial cough receptors.
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PMID:Inhaled furosemide inhibits cough induced by low chloride content solutions but not by capsaicin. 236 61

We investigated whether stimulation of vagal afferent nerve fibers with inhaled capsaicin could induce a nonadrenergic inhibitory reflex in nine mild asthmatic subjects. Changes in total respiratory resistance (Rrs) were measured with a forced oscillation technique. First we induced a rise of 71 +/- 15% in Rrs (P less than 0.001) after leukotriene D4 aerosol. Subsequent inhalation of capsaicin (2 nmol) caused no significant change in mean Rrs of -1.1 +/- 8.2%. After the muscarinic receptor antagonist ipratropium bromide (120 micrograms) was inhaled, leukotriene D4 increased Rrs by 103 +/- 9% (P less than 0.001). Capsaicin subsequently caused bronchodilation in all subjects (Rrs = -22.3 +/- 2.7%, P less than 0.001). Ethanol-saline (diluent) alone caused a nonsignificant fall in Rrs (-9.9 +/- 4.7%) but a deep breath and coughing resulted in bronchodilation (-16.9 +/- 6.1%, P less than 0.05 and -11.6 +/- 2.9%, P less than 0.01, respectively). As observed in normal subjects, capsaicin may initiate an inhibitory reflex, presumably of nonadrenergic origin. This reflex could not be distinguished from that caused by coughing or by deep inhalation. A defect in nonadrenergic mechanisms, at least in mild asthma, seems unlikely.
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PMID:Capsaicin-induced bronchodilation in mild asthmatic subjects: possible role of nonadrenergic inhibitory system. 252 37

Prostaglandins may cause hyperresponsiveness to bronchoconstrictor agents in the lung and hyperalgesia in the skin. Increased airway concentration of both prostaglandins and bradykinin has been suggested as the possible cause of the increased cough sensitivity sometimes found in patients with cough associated with taking drugs that inhibit angiotensin-converting enzyme. We have therefore investigated the effect of prostaglandin E2 (PGE2), bradykinin (BK), histamine (H), and citric acid (C) on capsaicin-induced cough and increase in respiratory resistance (Rrs). Capsaicin-induced changes in Rrs and dose-cough response were measured before and after inhaling 0.76 mumol of PGE2, BK, H, and C. All the test substances caused cough, which was subject to tachyphylaxis, but no significant change in Rrs. Neither BK, H, nor C altered the capsaicin cough or Rrs response. However, PGE2 significantly increased both responses to capsaicin, the geometric mean (95% Cl) for the dose of capsaicin causing 5 or more coughs being 16.2 (14.3 to 18.3) nmol before and 4.4 (2.4 to 7.9) nmol after PGE2 (p less than 0.05). The percent increase (95% Cl) in Rrs after capsaicin was 20 (16.5 to 23.5)% before and 37.2 (32.2 to 43.2)% after PGE2 (p less than 0.05). The results suggest that the cough reflex will be increased in the presence of PGE2 in the airway.
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PMID:Sensitivity of the human cough reflex: effect of inflammatory mediators prostaglandin E2, bradykinin, and histamine. 275 Nov 60

Neural pathways involved in cough and reflex bronchoconstriction and the effects of drugs on these airway reflexes have been studied in unanaesthetised guinea-pigs exposed to aerosols of citric acid (0.13-0.78 M), capsaicin (30 microM), nicotine (9.2 mM) and histamine (0.9 mM). The number of coughs was counted during the first 3 min of exposure and the time to onset of signs of dyspnea, as an indication of bronchoconstriction, was measured. Citric acid produced bronchoconstriction and dose-dependently increased the number of coughs. Capsaicin produced both cough and bronchoconstriction. Nicotine mainly produced cough and histamine bronchoconstriction. Pretreatment of adult guinea-pigs with capsaicin (50 mg kg-1 s.c.) produced a long-lasting (greater than or equal to 10 weeks) depletion of substance P- and calcitonin gene related peptide-like immunoreactivities in the sensory nerves of the larynx, tracheobronchial tree and lung. In capsaicin-treated animals, citric acid (0.39 M) and capsaicin (30 microM) caused neither cough nor bronchoconstriction. Nicotine (9.2 mM) and mechanical stimulation still produced cough, and histamine (0.9 mM) bronchoconstriction. It is concluded that in guinea-pigs both capsaicin-sensitive (probably C-fibre endings) and capsaicin-resistant (probably rapidly adapting stretch receptors) afferent neurons may be involved in cough and reflex bronchoconstriction.
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PMID:Cough and bronchoconstriction mediated by capsaicin-sensitive sensory neurons in the guinea-pig. 298 Feb 86

The effect of inhaled capsaicin, the irritant extract of pepper, on airway tone has been studied in humans. Inhaled capsaicin (2.4 X 10(-10) and 2.4 X 10(-9) mol) caused a dose-dependent fall in specific airways conductance (maximum fall 28 +/- 19 and 38 +/- 19%, respectively; means +/- SD, n = 17). This was maximal within 20 s of exposure and lasted for less than 60 s. There was no difference in the magnitude or duration of bronchoconstriction between normal, smoking, or asthmatic subjects. Capsaicin also caused coughing and retrosternal discomfort. On repeated exposure to capsaicin, there was no evidence for a reduced response (tachyphylaxis). Ipratropium bromide (0.25 mg by inhalation) significantly (P less than 0.05) reduced the bronchoconstriction (maximum falls 34 +/- 14 and 15 +/- 9% after saline and ipratropium bromide, respectively; means +/- SD n = 6), indicating that it was dependent on a cholinergic vagal reflex rather than on local release of substance P from nerves in the airway. Inhaled sodium cromoglycate (10 mg by nebulizer or 40 mg as a dry powder), however, had no significant effect on the bronchoconstrictor response. Capsaicin may be a useful tool for investigating nonmyelinated nerve reflexes in human airways.
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PMID:Bronchoconstrictor response to inhaled capsaicin in humans. 315 68

The inhalation of capsaicin for 1 min, delivered as an aerosol by nebulising solutions of capsaicin at concentrations of 2-65 mumol 1(-1), caused dose-dependent coughing in normal volunteers and subjects with mild asthma. Capsaicin did not cause a feeling of breathlessness, and had no effect on forced expiratory volume in 1 s (FEV1) measured at the 1st, 5th and 9th min after the challenge was completed. Coughing started within seconds of applying the face mask, continued throughout the minute of capsaicin inhalation, and stopped within seconds of the mask being removed. In any one subject the number of coughs was reproducible when repeated on the same day or after an interval of several days. Experiments using local anaesthesia applied to the buccal mucosa or larynx indicated that the cough was caused by the stimulation of capsaicin-sensitive nerve terminals situated in the larynx. Cough response was not altered by the prior inhalation of sodium cromoglycate.
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PMID:Capsaicin inhalation in man and the effects of sodium cromoglycate. 642 16


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