Salbutamol: a new, selective beta-adrenoceptive receptor stimulant

1. Salbutamol is a beta-adrenoceptive receptor stimulant. Its pharmacological actions are reduced or abolished by beta-receptor antagonists.2. In anaesthetized animals, salbutamol, given intravenously, was slightly less active than isoprenaline in preventing spasm of bronchial smooth muscle but was considerably less active as a cardiac stimulant and vasodepressor substance. Its duration of action was about 2 to 3 times that of isoprenaline.3. Salbutamol given by mouth or aerosol to conscious guinea-pigs, greatly diminished bronchospasm caused by inhalation of acetylcholine. By mouth, salbutamol was more active and had a longer duration than isoprenaline or orciprenaline without affecting heart rate. By aerosol, salbutamol was approximately 10 times as active as isoprenaline and 100 times as active as orciprenaline. Its duration of action was much longer than that of isoprenaline or orciprenaline. Only isoprenaline produced an increase in heart rate by the aerosol route.4. On isolated guinea-pig trachea salbutamol had about 1/10 the activity of isoprenaline, on isolated atria about 1/2000.

A substance P antagonist inhibits vagally induced increase in vascular permeability and bronchial smooth muscle contraction in the guinea pig

Electrical stimulation of the cervical vagus nerve in anesthetized guinea pigs induced a rapid increase in respiratory insufflation pressure, suggesting increased airway resistance. After intravenous administration of a substance P (SP) antagonist, [D-Arg(1),D-Pro(2),D-Trp(7,9),Leu(11)]SP, the insufflation pressure response to vagal stimulation was reduced by 78% while the cardiovascular effects were unchanged. Histamine receptor-blocking agents were used to inhibit the effects of histamine release induced by the SP-antagonist. [D-Arg(1),D-Pro(2),D-Trp(7,9),Leu(11)]SP also reduced the increase in insufflation pressure caused by intravenous SP or capsaicin. The long-lasting noncholinergic contraction of the main and hilus bronchi induced by field stimulation in vitro, as well as the contractile effects of SP and capsaicin, were also blocked by the SP antagonist. The cholinergic contractions and the noncholinergic tracheal relaxation on field stimulation in vitro were, however, not blocked by the antagonist. Vagal stimulation in vivo also increased vascular permeability in the respiratory tract and esophagus, causing a subepithelial edema as indicated by Evans blue extravasation. Previous treatment with [D-Arg(1),D-Pro(2),D-Trp(7,9),Leu(11)]SP inhibited the permeability increase induced by both vagus nerve stimulation and exogenous SP. SP release from vagal sensory nerves was indirectly shown by reduction in the bronchial levels of SP after nerve stimulation in vivo. The data suggest that a major portion of the vagally or capsaicin-induced increase in smooth muscle tone is caused by SP release from sensory neurons. In addition, activation of vagal SP-containing sensory nerves induces local edema. Tracheobronchial afferent SP-containing C fibers may thus exert local control of smooth muscle tone and vascular permeability in normal and pathophysiological conditions.

Anti-inflammatory, analgesic, antipyretic and related properties of meloxicam, a new non-steroidal anti-inflammatory agent with favourable gastrointestinal tolerance

The anti-inflammatory, analgesic and antipyretic properties of the new non-steroidal anti-inflammatory agent, meloxicam, were investigated in a variety of animal models and compared with the properties of piroxicam, diclofenac, indomethacin and several other NSAIDs. With respect to the total effect of a single oral dose, the anti-exudative effect of meloxicam on carrageenan-induced oedema in the rat exceeded that of all the NSAIDs included in the comparison. Additionally, meloxicam showed the greatest potency of all the compounds examined with respect to adjuvant-induced arthritis in the rat, the granuloma pouch model and the cotton pellet test in the rat. Unlike indomethacin, in the carrageenan pleurisy model in the rat, meloxicam caused both a dose-dependent reduction in exudate volume and also inhibition of leucocyte migration. Meloxicam showed a strong and lasting effect on inflammatory pain in the rat. Like other NSAIDs, but unlike dipyrone, meloxicam had no effect in the hot plate and tail clamp tests, which are used to identify weak central analgesic effects. Unlike dipyrone and like indomethacin, meloxicam had no effect in a model of visceral distention pain. In common with other NSAIDs, meloxicam had no influence on the body temperature of normothermic rats in the anti-inflammatory dose range, but did reduce yeast-induced fever in the rat in a dose-dependent manner. Like piroxicam, meloxicam had a uricosuric effect on rats treated with oxonic acid. Low-dose meloxicam inhibited both bradykinin-induced and PAF-induced bronchospasm in the guinea-pig, but had no effect on acetylcholine-induced bronchospasm. Piroxicam had greater ulcerogenic effects in the rat stomach than meloxicam. The therapeutic range of meloxicam in the rat, with regard to inhibition of adjuvant arthritis, was several times greater than that of piroxicam, indomethacin, diclofenac and naproxen.

The safety of intravenous dipyridamole thallium myocardial perfusion imaging. Intravenous Dipyridamole Thallium Imaging Study Group

Clinical data on 3,911 patients were collected from 64 individual investigators to evaluate the safety of intravenous dipyridamole-thallium imaging as an alternative to exercise thallium imaging for the evaluation of coronary artery disease. There were two deaths because of myocardial infarctions, two nonfatal myocardial infarctions, and six cases of acute bronchospasm. Chest pain occurred in 770 patients (19.7%). Headache and dizziness were reported by 476 patients (12.2%) and 460 patients (11.8%), respectively. ST-T changes on the electrocardiogram were seen in 292 patients (7.5%). Use of parenteral aminophylline to treat adverse events associated with intravenous dipyridamole brought complete relief of symptoms in 439 of 454 patients (96.7%). There is a potential for increased risk for serious ischemic events in patients with a history of unstable angina who are administered intravenous dipyridamole. In patients with acutely unstable angina (i.e., continuing chest pain) or in the acute phase of myocardial infarction, use of intravenous dipyridamole in thallium scintigraphy should be avoided. There is also an increased risk for bronchospasm in patients with a history of asthma; acute bronchospasm can be relieved immediately by administration of aminophylline. These results demonstrate that intravenous dipyridamole-thallium scintigraphy is a relatively safe, noninvasive technique for the evaluation of coronary artery disease.

Airway and tissue mechanics in a murine model of asthma: alveolar capsule vs. forced oscillations

To better address the functional consequences of inflammation on bronchial responsiveness, we studied two groups of BALB/c mice: a nonimmunized control group (n = 8) and a group immunized and challenged with inhaled ovalbumin (n = 8). An alveolar capsule (AC) measured airway resistance (Raw(AC)) and lung elastance (EL). A forced oscillation (FO) technique independently estimated airway resistance (Raw(FO)) and a parameter H(ti) related to tissue elastance. Ovalbumin-immunized and -challenged mice had increased numbers of eosinophils in bronchoalveolar lavage and increased responsiveness to methacholine (MCh). Corresponding parameters from the AC and FO techniques were correlated: Raw(AC) vs. Raw(FO) (r = 0.76) and EL vs. H(ti) (r = 0.88, P < 0.0001 in all cases). AC and FO techniques showed significant increases in tissue elastance in response to MCh but no significant increases in airway resistance. These results demonstrated that the AC and FO techniques yield essentially equivalent results in mice, even when the lung is inhomogeneous, and that the bronchoconstrictive responses to MCh and inflammation in mice are predominantly located in the lung periphery.

Brain ATP depletion induced by acute ammonia intoxication in rats is mediated by activation of the NMDA receptor and Na+,K(+)-ATPase

Injection of large doses of ammonia into rats leads to depletion of brain ATP. However, the molecular mechanism leading to ATP depletion is not clear. The aim of the present work was to assess whether ammonium-induced depletion of ATP is mediated by activation of the NMDA receptor. It is shown that injection of MK-801, an antagonist of the NMDA receptor, prevented ammonia-induced ATP depletion but did not prevent changes in glutamine, glutamate, glycogen, glucose, and ketone bodies. Ammonia injection increased Na+,K(+)-ATPase activity by 76%. This increase was also prevented by previous injection of MK-801. The molecular mechanism leading to activation of the ATPase was further studied. Na+,K(+)-ATPase activity in samples from ammonia-injected rats was normalized by "in vitro" incubation with phorbol 12-myristate 13-acetate, an activator of protein kinase C. The results obtained suggest that ammonia-induced ATP depletion is mediated by activation of the NMDA receptor, which results in decreased protein kinase C-mediated phosphorylation of Na+,K(+)-ATPase and, therefore, increased activity of the ATPase and increased consumption of ATP.

Adverse reactions to acetylcysteine and effects of overdose

Since the introduction in 1979 of intravenous acetylcysteine (Parvolex) as an antidote for overdosage of paracetamol the National Poisons Information Service and the manufacturer have been notified of 38 adverse reactions that were anaphylactoid in nature and 19 accidental overdoses. The most common feature of the anaphylactoid reaction to normal dosage was rash; other features reported included angioedema, hypotension, and bronchospasm; all the patients recovered. The features associated with an overdose of acetylcysteine were similar but more severe; two patients died, but the extent to which the overdose of acetylcysteine may have been implicated was not clear in either case.

Bidirectional control of airway responsiveness by endogenous cannabinoids

Smoking marijuana or administration of its main active constituent, delta9-tetrahydrocannabinol (delta9-THC), may exert potent dilating effects on human airways. But the physiological significance of this observation and its potential therapeutic value are obscured by the fact that some asthmatic patients respond to these compounds with a paradoxical bronchospasm. The mechanisms underlying these contrasting responses remain unresolved. Here we show that the endogenous cannabinoid anandamide exerts dual effects on bronchial responsiveness in rodents: it strongly inhibits bronchospasm and cough evoked by the chemical irritant, capsaicin, but causes bronchospasm when the constricting tone exerted by the vagus nerve is removed. Both effects are mediated through peripheral CB1 cannabinoid receptors found on axon terminals of airway nerves. Biochemical analyses indicate that anandamide is synthesized in lung tissue on calcium-ion stimulation, suggesting that locally generated anandamide participates in the intrinsic control of airway responsiveness. In support of this conclusion, the CB1 antagonist SR141716A enhances capsaicin-evoked bronchospasm and cough. Our results may account for the contrasting bronchial actions of cannabis-like drugs in humans, and provide a framework for the development of more selective cannabinoid-based agents for the treatment of respiratory pathologies.

Incidence of bronchoconstriction due to aspirin, azo dyes, non-azo dyes, and preservatives in a population of perennial asthmatics

Forty-five patients with moderately severe perennial bronchial asthma were challenged by ingestion of: acetylsalicyclic acid (ASA); 4 azo dyes (tartrazine, sunset yellow, amaranth, and ponceau); 3 non-azo dyes (erythrosine, brilliant blue, and indigotin); sodium benzoate (NaB); parahydroxybenzoic acid (OHBA); butylated hydroxyanisole (BHA); and butylated hydroxytoluene (BHT). A fall in forced expiratory volume is one second (FEV1) greater than 25% from baseline was considered positive. Seven patients who gave an unequivocal history of aspirin intolerance were not challenged with ASA; an additional 13 had positive open challenges to ASA, giving an apparent incidence of aspirin sensitivity of 20/45. The presence of nasal polyps, simusitis, or the regular use of corticosteroids, either singly or in combination, was not associated with an increased incidence of reactions to ASA. Significant bronchoconstriction to open challenges with agents other than ASA was less frequent. Positive open challenges to all substances except aspirin were followed by double-blind challenges which were positive in only 3 instances: 1 each with erythrosine, ponceau, and NaB/OHBA. Our findings confirm that ASA intolerance is relatively common but suggest on the other hand that reactions to dyes and preservatives are uncommon cause of clinically significant bronchoconstriction in moderately severe perennial asthmatics.

Bronchoconstrictor response to inhaled capsaicin in humans

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.

The effect of age on methacholine response

Bronchial reactivity to inhaled methacholine exists in subjects with asthma but may occur in subjects with allergic rhinitis, chronic lung diseases, and during respiratory infections. In the absence of these factors, we found that age also has a significant effect on the methacholine response. One hundred forty-eight subjects, 5 to 76 years of age, were studied as normal control subjects in a natural history of asthma study. The methacholine response was measured by standard techniques. The analysis demonstrated that age had a significant effect on the methacholine response. In addition to known factors influencing the results of methacholine inhalation, young and older subjects may exhibit bronchial responses that may falsely suggest hyperreactive airway disease.

Adverse reactions to intravenous anaesthetics

One hundred consecutive reports of reactions to intravenous anaesthetics Althesin, thiopentone and Epontol are reviewed and analysed. Ten reactions are attributed to causes other than the anaesthetic drug, and four are believed to have been caused by the muscle relaxant employed. The remaining 86 reactions were grouped according to their clinical presentation: histaminoid reactions ( 19), histaminoid with bronchospasm (33), bronchospasm (12), cardiovascular collapse (uu), delayed histaminoid reactions (6), and clonic contractions (5). None of the first four reaction types was associated with only one anaesthetic. A knowledge of the sales of Althesin has allowed the incidence of reactions to be estimated as between one in 11,000 and one in 19,000.

The contribution of histamine to immediate bronchoconstriction provoked by inhaled allergen and adenosine 5' monophosphate in atopic asthma

In order to investigate the contribution of histamine to bronchoconstriction provoked by inhaled allergen and adenosine monophosphate (AMP), we have observed the effects of prior treatment with the potent H1-receptor antagonists, terfenadine and astemizole. Nine mild, atopic asthmatics underwent inhalation challenge tests on 6 separate days with histamine, allergen extract, and AMP using single concentrations previously shown to produce a 30% fall in FEV1. For each agonist, bronchoprovocation was performed 3 h after treatment with either terfenadine 180 mg or matched placebo, and airway caliber assessed by measurement of FEV1 over a period of 45 min. AMP challenge was also performed after prior treatment with astemizole. After placebo, histamine produced rapid bronchoconstriction, reaching a maximum within 5 min and returning to within 10% of baseline at 25 min. Pretreatment with terfenadine abolished the bronchoconstrictor response to histamine completely. In contrast, bronchoconstriction provoked by allergen after placebo was slower in onset and sustained during the 45 min of observation. Terfenadine only partially inhibited this response to allergen by 50 +/- 10% (mean +/- SEM) with the maximal effect being observed within the first 5 to 8 min of challenge. AMP inhalation provoked rapid bronchoconstriction similar in time course to that of histamine, and this reaction was inhibited by 86 +/- 8.1% by terfenadine. Astemizole produced inhibition of the response to AMP that was almost identical to that of terfenadine. On the basis of in vitro studies, we interpret these differential effects of terfenadine as reflecting the contribution of histamine to the various airway challenges.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of the vagus nerves in anaphylaxis and histamine-induced bronchoconstrictions in guinea-pigs

1. The effects of vagotomy on the respiratory responses of guinea-pigs to anaphylactic reactions and to intravenous injections of histamine acid phosphate are described.2. In spontaneously breathing guinea-pigs, vagotomy reduced by 50% or more the decreases in total lung conductance (bronchoconstriction) and the decreases in lung compliance, and almost abolished the rapid shallow breathing due to histamine.3. In paralysed, artificially ventilated guinea-pigs, vagotomy reduced by more than 33% the decreases in total lung conductance, but had little effect on the changes in lung compliance due to histamine.4. In paralysed, artificially ventilated guinea-pigs, vagotomy reduced by 75% the decrease in total lung conductance and halved the decrease in lung compliance due to anaphylaxis.5. We conclude that a vagal reflex is mainly responsible for the rapid shallow breathing due to histamine, and partly responsible for the bronchoconstrictions due to histamine and to anaphylaxis in guinea-pigs. We suggest that "lung irritant receptors" in the bronchial epithelium are the afferent end-organs involved.

Inhaled nitric oxide. A bronchodilator in mild asthmatics with methacholine-induced bronchospasm

Nitric oxide (NO) reduces airway tone in the methacholine-treated guinea pig. We examined whether low levels of inhaled NO gas would relax airway smooth muscle tone in patients with mild asthma subjected to methacholine-induced bronchospasm. Thirteen adult volunteers with mild asthma inspired increasing concentrations of methacholine until their baseline forced expiratory volume in one second (FEV1, 3.29 +/- 0.17 L, mean +/- SEM) decreased by > or = 20% (2.33 +/- 0.18 L, p < 0.01). Thereafter, they sequentially inhaled 100 parts per million (ppm) NO, 40% O2; 40% O2; and 100 ppm NO, 40% O2 while spirometry was performed. Subsequent inhalation of isoproterenol returned the FEV1 levels to baseline. Inhaling 100 ppm NO increased FEV1 to 2.66 +/- 0.18 L (p < 0.01), and this increase was maintained after NO was discontinued. FEV1 did not change during the second period of NO inhalation. Similar results were observed for vital capacity, but no significant effect was noted on forced expiratory flow at 25% of vital capacity or peak expiratory flow. Subjects were then divided into a responder subgroup, which showed a mean increase in FEV1 after initial NO inhalation of 560 +/- 150 ml, and a nonresponder subgroup, which showed a mean increase in FEV1 of 129 +/- 29 ml. Our data suggest that inhalation of nitric oxide by patients with mild asthma with methacholine-induced bronchospasm results in a minor but significant relaxation of airway tone.

Ba 679 BR, a novel long-acting anticholinergic bronchodilator

The use of anticholinergics in antiobstructive therapy is well established in pulmonary medicine. We sought to improve the duration of action of inhaled antimuscarinics. A newly developed compound, Ba 679 BR (abbreviated Ba 679) proved to be a highly potent muscarinic antagonist in guinea pig tracheal rings. Its binding to human receptors (Hm1, Hm2, Hm3) was characterized by KD-values in the 10(-10) M concentration range. Assessment of the dissociation rate of complexes of labelled Ba 679 and human muscarinic receptors revealed very slow dissociation in comparison to ipratropium. The half-lives in hours were: Ba 679-Hm3: 34.7, -Hm1: 14.6, -Hm2: 3.6; ipratropium-Hm3: 0.26, -Hm1: 0.11, -Hm2: 0.035. The duration of action in vivo was determined by means of acetylcholine-induced bronchospasms in dogs following inhalation of the drugs. Ba 679 demonstrated a significantly longer duration of protection than an equipotent dose of ipratropium. The plasma levels following inhalation in dogs declined rapidly and are unlikely to reflect the duration of the pharmacological activity. In summary, Ba 679 represents a novel type of antimuscarinic bronchodilator with a long duration of action, most likely due to its slow dissociation from Hm3-receptors. In addition, the drug showed "kinetic receptor subtype selectivity" by having a more rapid dissociation from Hm2 than from Hm1 and Hm3 receptors.

Hypersensitivity reactions to carboplatin administration are common but not always severe: a 10-year experience

We have retrospectively evaluated and characterized the hypersensitivity reactions associated with carboplatin administration in ovarian cancer patients treated mainly on an outpatient basis at the Laikon Hospital from 1988 to 1998. A total of 240 patients, who had never been exposed to platinum compounds previously, received carboplatin plus cyclophosphamide (n = 58) or paclitaxel (n = 136) intravenously, and intraperitoneal carboplatin plus intravenous cyclophosphamide (n = 46). The median number of carboplatin courses was 6 (range 3-12) and 5 (range 4-6) for the intravenous and intraperitoneal treatment regimens, respectively. Thirty-two of 194 patients (16%) who were on intravenous carboplatin treatment developed symptoms compatible with a hypersensitivity reaction to carboplatin, that was always verified by manifestation of at least similar symptoms on rechallenging. In contrast, in the group of 46 patients on intraperitoneal carboplatin treatment, no hypersensitivity reaction was ever noticed. Hypersensitivity reactions always occurred after administration of the first 4 intravenous courses of carboplatin; 4, 19, 4, and 5 reactions occurred at the 5th, 6th, 7th, and 8th courses, respectively. These reactions could be distinguished in: (a) mild hypersensitivity reactions in 20 of 194 patients, which manifested as itching (20 patients) and small area erythema plus erythema of the palms and soles (12 patients), occurring either during intravenous injection when most of the drug scheduled had been administered, or within 3 days, and (b) in severe reactions in 12 of 194 patients, which manifested acutely as itching, diffuse erythroderma, rigor, facial swelling, throat and chest tightness, tachycardia (12 patients) and bronchospasm (2 patients), and hypertension or hypotension in 8 and 4 patients, respectively. With appropriate symptomatic management, discontinuation of carboplatin treatment was not required in patients with mild hypersensitivity reactions, but none of the 12 patients with severe reactions was able to receive a full subsequent dose of carboplatin on rechallenging. However, in 4 of these 12 patients carboplatin was replaced by cisplatin, which was given for 4-6 courses without side effects. These findings indicate that although hypersensitivity reactions are common in general, occurring in almost 1 of every 6 patients treated intravenously with carboplatin, their clinical picture is variable, leading to discontinuation of treatment in only 6% of patients. This is not the case when the intraperitoneal route of carboplatin administration is used when indicated.

Fatal asthma in a subject sensitized to toluene diisocyanate

We report the case of a 43-yr-old car painter who died within 1 h of exposure to a polyurethane paint in the workplace. A diagnosis of asthma induced by toluene diisocyanate (TDI) had been established 6 yr before, when he underwent inhalation challenges with carbachol and with TDI. The subject had airway hyperresponsiveness to carbachol (PD20FEV1 carbachol = 0.32 mg; normal value greater than 1.0 mg) and developed an early and long-lasting asthmatic reaction after exposure to TDI in the laboratory. Although it was recommended that he change his job or stop using paints containing isocyanates, he continued to work as a car painter, taking antiasthmatic drugs both at work and at home to control asthma symptoms. On Monday, October 6, 1986, at 11:30 A. M., he developed a severe attack of asthma while he was mixing the 2 components of a polyurethane paint. Taken to hospital, he was dead on arrival. Autopsy showed no evidence of cardiac or brain disease; lungs were overinflated, the cut surface showed grey glistening mucous plugs in in the airways. Histologic examination showed denudation of airway epithelium and thickening of the basement membrane with infiltration of the lamina propria by polymorphonuclear leukocytes, mainly eosinophils, and diffuse mucous plugging of bronchioles. Bronchial smooth muscle appeared hyperplastic and disarrayed, and lung parenchyma showed focal areas of alveolar destruction adjacent to areas of perfectly intact alveolar walls.(ABSTRACT TRUNCATED AT 250 WORDS)

Selective type IV phosphodiesterase inhibitors as antiasthmatic agents. The syntheses and biological activities of 3-(cyclopentyloxy)-4-methoxybenzamides and analogues

The syntheses and biological activities of a number of benzamide derivatives, designed from rolipram, which are selective inhibitors of cyclic AMP-specific phosphodiesterase (PDE IV), are described. The effects of changes to the alkoxy groups, amide linkage, and benzamide N-phenyl ring on the inhibition of the cytosolic PDE IV from pig aorta have been investigated. As a result, some highly potent and selective PDE IV inhibitors have been identified. The most potent compounds have been further evaluated for their inhibitory potencies against PDE IV obtained from and superoxide O2- generation from guinea pig eosinophils in vitro. Selected compounds have also been examined for their activities in inhibiting histamine-induced bronchospasm in anaesthetized guinea pigs. 3-(Cyclopentyloxy)-N-(3,5-dichloro-4-pyridyl)-4-methoxybenzamide (15j) showed exceptional potency in all tests and may have therapeutic potential in the treatment of asthma.