A comparative study of the effects of ketotifen, disodium cromoglycate, and beclomethasone dipropionate on bronchial mucosa and asthma symptoms in patients with atopic asthma.
(1/98)
Asthma is a chronic inflammatory disorder of the airways that is characterized by infiltration of many inflammatory cells into the bronchial mucosa. We compared the effects of ketotifen, disodium cromoglycate (DSCG), and beclomethasone dipropionate (BDP) on inflammatory cells in the bronchial mucosa and on the asthma symptoms of patients with atopic asthma. In this 12-week parallel study, 32 patients were randomly allocated to either the ketotifen group (2 mg day-1, n = 13), DSCG group (8 mg day-1, n = 9) or BDP (400 micrograms day-1, n = 10). Each subject recorded daily asthma symptoms and peak expiratory flow (PEF). Before and after treatment, pulmonary function and bronchial responsiveness to methacholine were evaluated, and fibreoptic bronchoscopy and biopsy were performed before and after treatment. Biopsy specimens were obtained by bronchoscopy. We performed immunohistochemistry using specific monoclonal antibodies for activated eosinophils (EG2), mast cells (AA1), and T cells (CD3, CD4, and CD8). Our clinical findings showed significant improvement in symptom score and bronchial responsiveness (P < 0.01) each) in all groups. Both the DSCG and the BDP groups had significantly better symptom scores than the ketotifen group (P < 0.05, both groups). PEF significantly increased in the DSCG group in comparison to the ketotifen (P < 0.01) and BDP (P < 0.05) groups, FEV1% increased significantly in the DSCG (P < 0.01) and BDP (P < 0.05) groups in comparison to the ketotifen group. Compared with their baseline values, treatment significantly decreased EG2+ activated eosinophils, and CD3+ and CD4+ T cells, in each group (P < 0.01). Both the DSCG (P < 0.05) and the BDP groups (P < 0.01) exhibited significant decreases in AA1+ mast cell count, but this was not observed in the ketotifen group. Comparing before- and after-treatment values, only the DSCG group exhibited a significant decrease in the number of CD8+ T cells (P < 0.01). Ketotifen, DSCG, and BDP all showed anti-inflammatory activity as determined by examination of the bronchial mucosa of asthmatic patients; and both the DSCG and BDP groups had better clinical responses than the ketotifen group. (+info)
Ketotifen and cardiovascular effects of xamoterol following single and chronic dosing in healthy volunteers.
(2/98)
AIMS: To study whether desensitization occurs after long-term administration of the 1-adrenoceptor partial agonist xamoterol and, if so, whether this can be influenced by ketotifen. METHODS: In a double-blind, randomized design 10 young, healthy males received ketotifen (2 x 1 mg day(-1) p.o.) or placebo for 3 weeks with xamoterol (2 x 200 mg day(-1) p.o.) administered concomitantly during the last 2 weeks. 'l1-adrenoceptor mediated responses were assessed as exercise-induced tachycardia and isoprenaline-induced shortening of heart rate corrected electromechanical systole (QS2c); isoprenaline-induced tachycardia was measured as a mixed beta1-/beta2-adrenoceptor-mediated effect. RESULTS: The first dose of xamoterol significantly increased resting heart rate and systolic blood pressure and significantly shortened QS2c. The last dose of xamoterol after 2 weeks of treatment still produced the same responses. Ketotifen did not influence these effects of xamoterol on resting haemodynamics. The first dose of xamoterol caused a rightward shift of the exercise- and isoprenaline-induced tachycardia (mean dose ratios+/-s.e.mean: 1.20+/-0.05 and 2.46+/-0.23) and the isoprenaline-evoked shortening of QS2c (dose ratio 3.59+/-0.68). This rightward shift was even more pronounced after 2 weeks xamoterol treatment. This additional rightward shift after 2 weeks of xamoterol was not affected by ketotifen (mean difference (95% CI) of log transformed dose ratios between placebo and ketotifen: exercise tachycardia 0.001 (-0.03; 0.04); isoprenaline tachycardia 0.03 (-0.15; 0.21); isoprenaline induced shortening of QS2c 0.13 (-0.22; 0.48)). CONCLUSIONS: In humans xamoterol is a partial beta1-adrenoceptor agonist with positive chrono- and inotropic effects at rest and antagonistic properties under conditions of beta-adrenoceptor stimulation. These effects were well maintained after chronic dosing with no signs of beta1-adrenoceptor desensitization. Ketotifen does not change the beta-adrenoceptor mediated responses of xamoterol after chronic dosing. (+info)
Evidence that mast cell degranulation, histamine and tumour necrosis factor alpha release occur in LPS-induced plasma leakage in rat skin.
(3/98)
1. In the present study we investigated the role of mast cells during inflammation in rat skin. As the release of several pro-inflammatory mediators, such as histamine and tumour necrosis factor alpha (TNFalpha), occurs following mast cell activation we studied whether mast cell degranulation and the release of both histamine (H) and TNFalpha occurred in a model of lipopolysaccharide (LPS)-induced plasma leakage in rat skin. 2. Plasma leakage in the rat skin was measured over a period of 2 h as the local accumulation of intravenous injection of 125I-human serum albumin (125I-HSA) in response to intradermal injection of LPS. LPS (10 microg site-1) produced an increase of plasma leakage (50.1+/-2.3 microl site-1) as compared to saline (9.0+/-3.2 microl site-1). Histological analysis of rat tissue showed that LPS induced a remarkable mast cell degranulation (59.8+/-2.1%) as compared to saline (13.5+/-2.2%). 3. Ketotifen (10-9 - 10-7 mol site-1), a well-known mast cell-membrane stabilizer, produced a dose-related inhibition of LPS-induced plasma leakage by 36+/-3.5%, 47+/-4.0%, 60+/-3.3% respectively. In addition, ketotifen (10-7 mol site-1) inhibited mast cell degranulation by 59. 2+/-2.7%. 4. Chlorpheniramine maleate (CPM) (10-9 - 10-7 mol site-1), an H1 histamine receptor antagonist only partially inhibited LPS-induced plasma leakage in rat skin (38+/-1.1% at the highest dose). Furthermore, CPM (10-7 mol site-1) did not prevent mast cell degranulation. 5. A polyclonal antibody against TNFalpha (1:500, 1:100, 1:50 v v-1 dilution), locally injected, decreased LPS-induced plasma leakage in the skin by 15+/-2.0%, 24+/-2.1% and 50+/-3.0% respectively. 6. Taken together these results suggest that LPS-induced plasma leakage in rat skin is mediated, at least in part, by mast cell degranulation and by the release of histamine and TNFalpha from these cells. (+info)
Conjugation of the enantiomers of ketotifen to four isomeric quaternary ammonium glucuronides in humans in vivo and in liver microsomes.
(4/98)
The antiallergic drug ketotifen is chiral due to a nonplanar seven-membered ring containing a keto group. Earlier studies have revealed glucuronidation at the tertiary amino group as a major metabolic pathway in humans. Chemical synthesis of glucuronides from racemic ketotifen now led to four isomers separable by HPLC of which two each could be ascribed to (R)-(+)- and (S)-(-)-ketotifen by synthesis from the enantiomers. According to (1)H NMR analysis of the (S)-ketotifen N-glucuronides, the conformation of the piperidylidene ring differs between the two isomers. Enzymatic hydrolysis with Escherichia coli beta-glucuronidase proceeded at a lower rate with the slower eluting (S)-ketotifen glucuronide than with the three other isomers. On incubation of the ketotifen enantiomers (0.5-200 microM) with human liver microsomes in the presence of UDP-glucuronic acid and Triton X-100, the N-glucuronides of (R)-ketotifen were produced with an apparent K(M) 15 microM and V(max) 470 pmol/min/mg protein. The two (S)-ketotifen glucuronides were formed by two-enzyme kinetics with K(M1) 1.3 microM and K(M2) 92 microM and V(max) values of 60 and 440 pmol/min/mg protein. After ingestion of 1 mg of racemic ketotifen, 10 healthy subjects excreted in urine 17 +/- 5% of the dose in the form of N-glucuronides. The (R)-ketotifen glucuronide isomers contributed one-sixth only, whereas the remainder consisted primarily of the (S)-ketotifen glucuronide isomer, which eluted last. Differential hydrolysis or membrane transport may be responsible for the discrepancy between N-glucuronide isomer ratios in vitro and in vivo. (+info)
Substance P may attenuate gastric hyperemia by a mast cell-dependent mechanism in the damaged gastric mucosa.
(5/98)
Calcitonin gene-related peptide (CGRP) released from sensory neurons, which are closely apposed to mast cells and blood vessels, mediates gastric hyperemia in response to acid challenge of the damaged mucosa. Substance P (SP) is coreleased with CGRP from sensory neurons, but the role of this peptide in gastric blood flow regulation is largely unknown. Chambered rat stomachs were exposed to 1.5 M NaCl and acidic saline after treatment with SP, aprotinin (serine protease inhibitor), and the mast cell stabilizers ketotifen and sodium cromoglycate (SCG). Gastric hyperemia (measured with a laser Doppler flow velocimeter) after hypertonic injury and acid challenge was nearly abolished by SP. Aprotinin infused together with SP and pretreatment with ketotifen and SCG before SP restored the gastric hyperemia. Ketotifen and SCG inhibited mast cell degranulation in SP-treated rats. Preservation of gastric hyperemia was correlated with improved mucosal repair. These data suggest that impaired hyperemia by SP during acid challenge of the gastric mucosa may be mediated by a mast cell-dependent mechanism involving the release of proteases from mast cells. (+info)
Leukocyte adhesion and microvessel permeability.
(6/98)
To investigate the direct effect of leukocyte adherence to microvessel walls on microvessel permeability, we developed a method to measure changes in hydraulic conductivity (L(p)) before and after leukocyte adhesion in individually perfused venular microvessels in frog mesentery. In 19 microvessels that were initially free of leukocyte sticking or rolling along the vessel wall, control L(p) was measured first with Ringer-albumin perfusate. Blood flow was then restored in each vessel with a reduced flow rate in the range of 30-116 microm/s to facilitate leukocyte adhesion. Each vessel was recannulated in 45 min. The mean number of leukocytes adhering to the vessel wall was 237 +/- 22 leukocytes/mm(2). At the same time, L(p) increased to 4.7 +/- 0.5 times the control value. Superfusion of isoproterenol (10 microM) after leukocyte adhesion brought the increased L(p) back to 1.1 +/- 0.2 times the control in 5-10 min (n = 9). Superfusing isoproterenol before leukocyte adhesion prevented the increase in L(p) (n = 6). However, the number of leukocytes adhering to the vessel wall was not significantly affected. These results demonstrated that leukocyte adhesion caused an increase in microvessel permeability that could be prevented or restored by increasing cAMP levels in endothelial cells using isoproterenol. Thus cAMP-dependent mechanisms that regulate inflammatory agent-induced increases in permeability also modulate leukocyte adhesion-induced increases in permeability but act independently of mechanisms that regulate leukocyte adhesion to the microvessel wall. Application of ketotifen, a mast cell stabilizer, and desferrioxamine mesylate, an iron-chelating reagent, attenuated the increase in L(p) induced by leukocyte adhesion, suggesting the involvement of oxidants and the activation of mast cells in leukocyte adhesion-induced permeability increase. Furthermore, with the use of an in vivo silver stain technique, the locations of the adherent leukocytes on the microvessel wall were identified quantitatively in intact microvessels. (+info)
Comparative N-glucuronidation kinetics of ketotifen and amitriptyline by expressed human UDP-glucuronosyltransferases and liver microsomes.
(7/98)
Like other basic amphiphilic drugs, the (S)-enantiomer of the antiallergic drug ketotifen exhibited biphasic kinetics when it was converted to two isomeric quaternary ammonium-linked glucuronides in human liver microsomes. For (R)-ketotifen this applied when incubations were carried out in the absence of a detergent. Two UDP-glucuronosyltransferases (UGTs) present in human liver, UGT1A4 and UGT1A3, were previously shown to catalyze tertiary amine N-glucuronidation when expressed in HK293 cells. Therefore, the conjugation kinetics of (R)- and (S)-ketotifen were investigated with the two expressed proteins. When homogenates of HK293 cells expressing UGT1A4 were incubated without detergent, N-glucuronidation kinetics were monophasic with K(M) values of 59 +/- 5 microM for (R)- and 86 +/- 26 microM for (S)-ketotifen. In experiments with membranes containing expressed UGT1A3, somewhat higher K(M) values were obtained. These values correspond to the high rather than to the low K(M) components of ketotifen glucuronidation in liver microsomes, the latter exhibiting K(M) values around 2 and 1 microM, respectively, with (R)- and (S)-ketotifen. With amitriptyline as the substrate, N-glucuronidation kinetics in the absence of detergent were biphasic in human liver microsomes and monophasic with a high K(M) value in cell homogenates containing UGT1A4. The results suggest that UGT1A4 and UGT1A3 catalyze high-K(M) N-glucuronidation of tertiary amine drugs, whereas the low-K(M) reaction requires either an alternative enzyme or a special conformation of UGT1A4 or UGT1A3 that can be attained in liver microsomes, but not in HK293 cell membranes. (+info)
Eosinophilic cystitis.
(8/98)
We describe four cases of eosinophilic cystitis in whom no specific cause could be found, and review the literature. Complaints at presentation included urgency, frequency, abdominal pain, and haematuria. In three patients the symptoms and ultrasound pictures suggested a bladder tumour. One patient was treated with anticholinergics and corticosteroids without relief of symptoms; a localised eosinophilic tumour was excised in one patient who remained symptom free; and two patients were managed conservatively with spontaneous resolution of bladder pathology and symptoms. One case was identified by random bladder biopsy in 150 consecutive patients with unexplained irritable micturition complaints. Eosinophilic cystitis is rare in children. After biopsy, we consider a wait and see policy is justified as symptoms tend to disappear spontaneously. Routine bladder biopsies in children with unexplained bladder symptoms is not justifiable. (+info)