Ketotifen. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in asthma and allergic disorders

The mast cell stabilizer ketotifen reduces joint capsule fibrosis in a rabbit model of post-traumatic joint contractures

OBJECTIVES

Using a rabbit model of post-traumatic joint contractures, we investigated whether treatment with a mast cell stabilizer after joint injury would lessen the molecular manifestations of joint capsule fibrosis.

METHODS

Surgical joint injury was used to create stable post-traumatic contractures of the knee in skeletally mature New Zealand white rabbits. Four groups of animals were studied: a non-operated control group (n = 8), an operated contracture group (n = 13) and two operated groups treated with the mast cell stabilizer, ketotifen, at doses of 0.5 mg/kg (n = 9) and 1.0 mg/kg (n = 9) twice daily. Joint capsule fibrosis was assessed by quantifying the mRNA and protein levels of α-SMA, tryptase, TGF-β1, collagen I and collagen III. Significance was tested using an ANOVA analysis of variance.

RESULTS

The protein and mRNA levels of α-SMA, TGF-β1, tryptase and collagen I and III were significantly elevated in the operated contracture group compared to control (p < 0.01). In both ketotifen-treated groups, protein and mRNA levels of α-SMA, TGF-β1 and collagen I were significantly reduced compared to the operated contracture group (p < 0.01).

CONCLUSIONS

These data suggest an inflammatory pathway mediated by mast cell activation is involved in joint capsule fibrosis after traumatic injury.

Optimization of cell-based assays to quantify the anti-inflammatory/allergic potential of test substances in 96-well format

OBJECTIVE

There is an insistent need for robust, reliable, and optimized assays for screening novel drugs targeting the inflammatory/allergic markers. The present study describes about the optimization of eight cell-based assays utilizing mammalian cell lines in 96-well format for quantifying anti-inflammatory/allergic drug candidates.

MATERIALS AND METHODS

We estimated the inhibitory response of reference compounds: 1400 W dihydrochloride on LPS-induced NO release, celecoxib on LPS-induced PGE(2) production and dexamethasone on LPS-induced pro-inflammatory cytokines IL-1 beta, IL-6, and TNF-alpha production by J774A.1 murine macrophages. Response of acetylsalicylic acid and celecoxib was studied on A23187-induced TXB(2) production; captopril on A23187-stimulated LTB(4) production by HL-60 cells. Effect of ketotifen fumarate was evaluated on A23187-elicited histamine release by RBL-2H3 cells. Each experiment was repeated twice to assess the reproducibility and suitability of the assays by determining appropriate statistical tools viz. %CV, S/B and Z' factor.

RESULTS

1400 W dihydrochloride was capable of inhibiting LPS-induced NO levels (IC(50) = 10.7 μM). Dexamethasone attenuated LPS-induced IL-1 beta (IC(50) = 70 nM), IL-6 (IC(50) = 58 nM) and TNF-alpha (IC(50) = 44 nM) release, whereas celecoxib, a specific COX-2 inhibitor showed marked reduction in LPS-induced PGE(2) (IC(50) = 23 nM) production. Captopril (IC(50) = 48 μM) and ketotifen fumarate (IC(50) = 36.4 μM) demonstrated potent inhibitory effect against A23187-stimulated LTB(4) and histamine levels, respectively. Both acetylsalicylic acid (IC(50) = 5.5 μM) and celecoxib (IC(50) = 7.9 nM) exhibited concentration-dependent decrease in TXB(2) production. Results for all the cell assays from two experiments showed a Z' factor varying from 0.30 to 0.99; the S/B ratio ranged from 2.39 to 24.92; %CV ranged between 1.52 and 20.14.

CONCLUSION

The results proclaim that these cell-based assays can act as ideal tools for screening new anti-inflammatory/anti-allergic compounds.

Comparative clinical evaluation of ketotifen and montelukast sodium in asthmatic Iraqi patients

Asthma is a common and chronic inflammatory condition of the airways whose cause is not completely understood. Although many classes of drugs are used for management of asthma, the response is variable due to multifactor reasons. This study was designed to evaluate the outcome of using ketotifen or montelukast sodium in Iraqi asthmatic patients. Single blinded randomized clinical trial was utilized, in which 100 asthmatic patients were recruited from Al-Karama hospital and randomized into two groups; 1st group (50 patients, treated with ketotifen for 4 weeks) and 2nd group (50 patients treated with montelukast sodium for 4 weeks). Asthma symptom score and wheezing were recorded at the beginning (first visit) and at the end of the study (after one month). Pulmonary function tests (PFTs) were performed by spirometry, and the patients' use of asthma drugs and their symptoms were evaluated at each visit. The result showed that asthma symptom, chest wheezing, and PFT values were significantly improved in the two groups at the end of the study compared to first visit (p < 0.05). All symptoms were significantly lower and PFT values were higher in the 2nd group compared to 1st group (p < 0.05). In conclusion, both ketotifen and montelukast sodium showed significant changes in asthma symptoms and PFT after one month of treatment, but the changes were more significant with montelukast group (2nd group) compared with ketotifen group (1st group) and this indicate that montelukast was more effective than ketotifen in treatment of asthmatic patients.

The mast cell stabilizer ketotifen fumarate lessens contracture severity and myofibroblast hyperplasia: a study of a rabbit model of posttraumatic joint contractures

BACKGROUND

The propensity of joints to become stiff after trauma is widely appreciated, and the joint capsule is commonly recognized as the major motion-limiting anatomical structure. Affected joint capsules become fibrotic, characterized by myofibroblast and collagen hyperplasia. Mast cell hyperplasia is common within fibrotic tissue, and mast cells are known to synthesize many profibrotic mediators. We hypothesized that mast cell inhibition after skeletal injury would lessen contracture severity and reduce myofibroblast hyperplasia within the joint capsule.

METHODS

Posttraumatic contractures of the knee were created with use of a combination of intra-articular injury and internal immobilization in skeletally mature New Zealand White rabbits. Four groups of animals were studied: a nonoperative control group, a group with the operatively created contracture and no pharmacological treatment (the operative contracture group), and two groups with the operatively created contracture that were treated with a mast cell stabilizer, ketotifen fumarate, at a dose of either 0.5 or 1.0 mg/kg twice daily (the 0.5-mg/kg and 1.0-mg/kg ketotifen groups). After eight weeks of immobilization, flexion contractures were measured and the posterior aspect of the joint capsule was harvested for quantification of myofibroblast and mast cell numbers.

RESULTS

Flexion contractures developed in the operative contracture group (mean and standard deviation, 58 degrees +/- 14 degrees ), and the severity of the contractures was reduced in both the group treated with 0.5 mg/kg of ketotifen (42 degrees +/- 17 degrees ) and the group treated with 1.0 mg/kg of ketotifen (45 degrees +/- 10 degrees ) (p < 0.02). The joint capsule myofibroblast and mast cell numbers in the operative contracture group were significantly increased compared with the values in the control group (p < 0.001), and the myofibroblast and mast cell numbers in both ketotifen groups were significantly reduced compared with the values in the operative contracture group (p < 0.001).

CONCLUSIONS

The use of a mast cell stabilizer, ketotifen, was effective in reducing the biomechanical and cellular manifestations of joint capsule fibrosis in a rabbit model of posttraumatic joint contracture. This finding suggests that an inflammatory pathway, mediated by mast cell activation, is involved in the induction of joint capsule fibrosis after traumatic injury.

Formulation of ketotifen fumarate fast-melt granulation sublingual tablet

The purpose of this study was to prepare sublingual tablets, containing the antiasthmatic drug ketotifen fumarate which suffers an extensive first-pass effect, using the fast-melt granulation technique. The powder mixtures containing the drug were agglomerated using a blend of polyethylene glycol 400 and 6000 as meltable hydrophilic binders. Granular mannitol or granular mannitol/sucrose mixture were used as fillers. A mechanical mixer was used to prepare the granules at 40 degrees C. The method involved no water or organic solvents, which are used in conventional granulation, and hence no drying step was included, which saved time. Twelve formulations were prepared and characterized using official and non official tests. Three formulations showed the best results and were subjected to an ex vivo permeation study using excised chicken cheek pouches. The formulation F4I possessed the highest permeation coefficient due to the presence of the permeation enhancer (polyethylene glycol) in an amount which allowed maximum drug permeation, and was subjected to a pharmacokinetic study using rabbits as an animal model. The bioavailability of F4I was significantly higher than that of a commercially available dosage form (Zaditen solution-Novartis Pharma-Egypt) (p > 0.05). Thus, fast-melt granulation allowed for rapid tablet disintegration and an enhanced permeation of the drug through the sublingual mucosa, resulting in increased bioavailabililty.

The role of mast cell stabilization in treatment of postoperative ileus: a pilot study

OBJECTIVES

Although postoperative ileus (POI) is considered multifactorial, intestinal inflammation resulting from manipulation-induced mast cell activation is recognized as an important pathophysiological mechanism. Therefore, mast cell stabilization may represent a new therapeutic approach to shortening POI. The aim of this paper was to study the effect of ketotifen, a mast cell stabilizer, on postoperative gastrointestinal transit in patients who underwent abdominal surgery.

METHODS

In this pilot study, 60 patients undergoing major abdominal surgery for gynecological malignancy with standardized anesthesia were randomized to treatment with ketotifen (4 or 12 mg) or placebo. Patients were treated for 6 days, starting 3 days before surgery. Gastric emptying of liquids, selected as a primary outcome parameter, was measured 24 h after surgery using scintigraphy. Secondary end points were (scintigraphically assessed) colonic transit, represented as geometrical center of activity (segment 1(cecum) to 7(stool)) and clinical parameters.

RESULTS

Gastric retention 1 h after liquid intake was significantly reduced by 12 mg (median 3% (1-7), P=0.01), but not by 4 mg ketotifen (18% (3-45), P=0.6) compared with placebo (16% (5-75)). Twenty-four hour colonic transit in placebo was 0.8 (0.0-1.1) vs. 1.2 (0.2-1.4) colon segments in the 12 mg ketotifen group (P=0.07). Abdominal cramps were significantly relieved in patients treated with 12 mg ketotifen, whereas other clinical parameters were not affected.

CONCLUSIONS

Ketotifen significantly improves gastric emptying after abdominal surgery and warrants further exploration of mast cell stabilizers as putative therapy for POI.

Efficacy of olopatadine HCI 0.1%, ketotifen fumarate 0.025%, epinastine HCI 0.05%, emedastine 0.05% and fluorometholone acetate 0.1% ophthalmic solutions for seasonal allergic conjunctivitis: a placebo-controlled environmental trial

PURPOSE

We aimed to compare the clinical efficacy and ocular surface variables of olopatadine, ketotifen fumarate, epinastine, emedastine and fluorometholone acetate ophthalmic solutions in preventing the signs and symptoms of seasonal allergic conjunctivitis (SAC).

METHODS

This was a prospective, randomized, double-blinded and placebo-controlled study. A total of 100 patients with SAC were randomly assigned to one of five groups, in which they were administered olopatadine, ketotifen fumarate, epinastine, emedastine or fluorometholone acetate, instilled twice daily for 2 weeks. One eye of each patient was treated with the study drug and the other was treated with a placebo. Signs and symptoms of allergic conjunctivitis (itching, redness, tearing, chemosis and eyelid swelling) were scored on a 4-point scale. Each symptom was assessed at baseline and then again after 1 and 2 weeks of treatment. Ocular surface variables were assessed by conjunctival impression cytology.

RESULTS

At weeks 1 and 2, all antiallergic agents were significantly more effective than placebo in alleviating itching, redness, tearing, chemosis and eyelid swelling. Fluorometholone acetate was significantly less effective than the other agents in reducing itching and redness at all control visits. Ocular surface findings by impression cytology improved significantly after all treatments compared with placebo.

CONCLUSIONS

In patients with SAC, olopatadine, ketotifen, epinastine and emedastine are more efficacious than fluorometholone acetate in preventing itching and redness. All the antiallergic agents gave similar results in terms of reducing tearing, chemosis and eyelid swelling. Our data showed that impression cytology parameters improved after treatment with antiallergic agents in patients with SAC.

ORIGINAL ARTICLE Effect of Ketotifen Fumarate, Olopatadine, and Levocabastine on Ocular Active Anaphylaxis in the Guinea Pig and Ocular Immediate Hypersensitivity in the Albino Rat

PURPOSE

To study the effects of ketotifen fumarate, olopatadine, and levocabastine on ocular active anaphylaxis in guinea pigs and on ocular immediate hypersensitivity in albino rats.

METHODS

Clinical grading scores and Evans blue dye leakage to eyelids and to eyeballs were assessed in five treatment groups (n = 10): ketotifen fumarate 0.025%, olopatadine 0.1%, levocabastine 0.05%, negative control, and positive control.

RESULTS

At 20 minutes after challenge, edema scores for ketotifen-treated guinea pigs were statistically significantly lower than those for levocabastine or olopatadine. Active treatment significantly reduced vascular leakage in both models. Ketotifen significantly reduced vascular leakage in eyelids compared with the other drugs. In guinea pigs, vascular leakage in eyeballs was significantly reduced with ketotifen fumarate compared with olopatadine and levocabastine.

CONCLUSIONS

In the guinea pig model, ketotifen was more effective than olopatadine and levocabastine at reducing conjunctival edema and vascular permeability in eyelids and eyeballs. In the rat model, ketotifen was more effective at reducing vascular permeability in eyelids than olopatadine and levocabastine.

Ketotifen-loaded microspheres prepared by spray-drying poly(D,L-lactide) and poly(D,L-lactide-co-glycolide) polymers: characterization and in vivo evaluation

Ketotifen (KT) was encapsulated into poly(D,L-lactide) (PLA) and poly(D,L-lactide-co-glycolide) (PLGA 50/50) by spray-drying to investigate the use of biodegradable drug-loaded microspheres as delivery systems in the intraperitoneal cavity. Ketotifen stability was evaluated by HPLC, and degradation was not observed. Drug entrapment efficiency was 74 +/- 7% (82 +/- 8 microg KT/mg for PLA) and 81 +/- 6% (90 +/- 7 microg KT/mg for PLGA 50/50). PLA microspheres released ketotifen (57% of encapsulated KT) in 350 h at two release rates (221 microg/h, 15 min to 2 h; 1.13 microg/h, 5-350 h). A quicker release of ketotifen took place from PLGA 50/50 microspheres (67.4% of encapsulated KT) in 50 h (322 microg/h, 15 min to 2 h; 16.18 microg/h, 5-50 h). After intraperitoneal administration (10 mg KT/kg b.w.), microsphere aggregations were detected in adipose tissue. Ketotifen concentration was determined in plasma by HPLC. The drug released from PLA and PLGA 50/50 microspheres was detected at 384 and 336 h, respectively. Noncompartmental analysis was performed to determine pharmacokinetic parameters. The inclusion of ketotifen in PLGA and PLA microspheres resulted in significant changes in the plasma disposition of the drug. Overall, these ketotifen-loaded microspheres yielded an intraperitoneal drug release that may be suitable for use as delivery systems in the treatment of inflammatory response in portal hypertension.

Ketotifen controlled release from cellulose acetate propionate and cellulose acetate butyrate membranes

Ketotifen was immobilised in cellulose acetate propionate (CAP) membranes and in cellulose acetate butyrate (CAB) membranes. The characteristics of each system were evaluated under a range of experimental conditions. The topography and uniformity of the membranes was assessed using scanning electron microscopy. The release characteristics associated with Ketotifen were monitored spectrophotometrically. The swelling capacity of the membranes was evaluated and attributed to the combined effects of diffusion and of complex dissociation, during swelling. The materials produced were able to provide controlled release of Ketotifen due to their controlled swelling behaviour and adequate release properties. The results showed that the release of Ketotifen from the CAB membranes is higher but the release from the CAP membranes is more uniform.

Stimulation of brain mast cells by compound 48/80, a histamine liberator, evokes renin and vasopressin release in dogs

Because degranulation of brain mast cells activates adrenocortical secretion (41, 42), we examined whether activation of such cells increases renin and vasopressin (antidiuretic hormone: ADH) secretion. For this, we administered compound 48/80 (C48/80), which liberates histamine from mast cells, to pentobarbital-anesthetized dogs. An infusion of 37.5 microg/kg C48/80 into the cerebral third ventricle evoked increases in plasma renin activity (PRA), and in plasma epinephrine (Epi) and ADH concentrations. Ketotifen (mast cell-stabilizing drug; given orally for 1 wk before the experiment) significantly reduced the C48/80-induced increases in PRA, Epi, and ADH. Resection of the bilateral splanchnic nerves (SPX) below the diaphragm completely prevented the C48/80-induced increases in PRA and Epi, but potentiated the C48/80-induced increase in ADH and elevated the plasma Epi level before and after C48/80 challenge. No significant changes in mean arterial blood pressure, heart rate, concentrations of plasma electrolytes (Na+, K+, and Cl-), or plasma osmolality were observed after C48/80 challenge in dogs with or without SPX. Pyrilamine maleate (H1 histaminergic-receptor antagonist) significantly reduced the C48/80-induced increase in PRA when given intracerebroventricularly, but not when given intravenously. In contrast, metiamide (H2 histaminergic-receptor antagonist) given intracerebroventricularly significantly potentiated the C48/80-induced PRA increase. A small dose of histamine (5 microg/kg) administered intracerebroventricularly increased PRA twofold and ADH fourfold (vs. their basal level). These results suggest that in dogs, endogenous histamine liberated from brain mast cells may increase renin and Epi secretion (via the sympathetic outflow) and ADH secretion (via the central nervous system).

Inflammation: a way to understanding the evolution of portal hypertension

BACKGROUND

Portal hypertension is a clinical syndrome that manifests as ascites, portosystemic encephalopathy and variceal hemorrhage, and these alterations often lead to death.

HYPOTHESIS

Splanchnic and/or systemic responses to portal hypertension could have pathophysiological mechanisms similar to those involved in the post-traumatic inflammatory response.The splanchnic and systemic impairments produced throughout the evolution of experimental prehepatic portal hypertension could be considered to have an inflammatory origin. In portal vein ligated rats, portal hypertensive enteropathy, hepatic steatosis and portal hypertensive encephalopathy show phenotypes during their development that can be considered inflammatory, such as: ischemia-reperfusion (vasodilatory response), infiltration by inflammatory cells (mast cells) and bacteria (intestinal translocation of endotoxins and bacteria) and lastly, angiogenesis. Similar inflammatory phenotypes, worsened by chronic liver disease (with anti-oxidant and anti-enzymatic ability reduction) characterize the evolution of portal hypertension and its complications (hepatorenal syndrome, ascites and esophageal variceal hemorrhage) in humans.

CONCLUSION

Low-grade inflammation, related to prehepatic portal hypertension, switches to high-grade inflammation with the development of severe and life-threatening complications when associated with chronic liver disease.

The mast cell integrates the splanchnic and systemic inflammatory response in portal hypertension

Portal hypertension is a clinical syndrome that is difficult to study in an isolated manner since it is always associated with a greater or lesser degree of liver functional impairment. The aim of this review is to integrate the complications related to chronic liver disease by using both, the array of mast cell functions and mediators, since they possibly are involved in the pathophysiological mechanisms of these complications. The portal vein ligated rat is the experimental model most widely used to study this syndrome and it has been considered that a systemic inflammatory response is produced. This response is mediated among other inflammatory cells by mast cells and it evolves in three linked pathological functional systems. The nervous functional system presents ischemia-reperfusion and edema (oxidative stress) and would be responsible for hyperdynamic circulation; the immune functional system causes tissue infiltration by inflammatory cells, particularly mast cells and bacteria (enzymatic stress) and the endocrine functional system presents endothelial proliferation (antioxidative and antienzymatic stress) and angiogenesis. Mast cells could develop a key role in the expression of these three phenotypes because their mediators have the ability to produce all the aforementioned alterations, both at the splanchnic level (portal hypertensive enteropathy, mesenteric adenitis, liver steatosis) and the systemic level (portal hypertensive encephalopathy). This hypothetical splanchnic and systemic inflammatory response would be aggravated during the progression of the chronic liver disease, since the antioxidant ability of the body decreases. Thus, a critical state is produced, in which the appearance of noxious factors would favor the development of a dedifferentiation process protagonized by the nervous functional system. This system rapidly induces an ischemia-reperfusion phenotype with hydration and salinization of the body (hepatorenal syndrome, ascites) which, in turn would reduce the metabolic needs of the body and facilitate its temporary survival.

Skin permeation of ketotifen applied from stick-type formulation

A stick-typed long lasting device for both transdermal and topical drug delivery has been developed. Ketotifen fumarate (KT) was used as a model drug. The effect of a variety of permeation enhancers was investigated using hairless mouse skin in vitro. Polyoxyethylene oleyl ether (POE), among the enhancers used, most enhanced the skin permeation of KT. The permeation enhancement was mainly due to the increase in the drug solubility in the stratum corneum and the resulting increase in the partition coefficient. The rate of skin permeation of KT was approximately proportional to the loading dose of the drug.

Suppressive effects of ketotifen on Th1- and Th2-related chemokines of monocytes

Ketotifen is a mast cell stabilizer and useful in younger children with allergic diseases such as asthma and allergic rhinitis. Macrophage-derived chemokine (MDC) is a T-helper cell type 2 (Th2)-related chemokine involved in recruitment of Th2 cells toward allergen-challenged inflammation. However, the Th1-related chemokines, interferon-inducible protein 10 (IP-10)/CXCL10, and the monokine induced by interferon-gamma (MIG)/CXCL9 are also important in allergen-induced asthma in animal models. We investigated the effects of ketotifen on the expression of Th1- and Th2-related chemokines of human monocytes in vitro and ex vivo. Ketotifen (5-50 microM) significantly down-regulated lipopolysaccharide (LPS)-induced MDC, MIG and IP-10 (p < 0.05, each comparison) in THP-1 cells and human primary monocytes in a dose-dependent manner. SB203580 [p38-mitogen-activated protein kinase (MAPK) inhibitor] suppressed LPS-induced MDC and IP-10 expression, and PD98059 (ERK-MAPK inhibitor) could only suppress LPS-induced IP-10, but not MDC expression. LPS-induced pp38 and p-ERK expression of THP-1 monocytic cells was suppressed by ketotifen. These data demonstrate that ketotifen is effective in down-regulating LPS-induced MDC, MIG and IP-10, which play important roles in the pathogenesis of airway inflammation. The suppressive effect on MDC and IP-10 may, at least in part, involve the down-regulation of LPS-induced p38 and ERK-MAPK expression.

Immune response and inhibitory effect of ketotifen on the BALB/c and C3H/HeN mice infected with Echinostoma hortense

Although Echinostoma hortense is one of the intestinal trematodes with a high infection rate in South Korea, the exact immune response against E. hortense infection has yet to be fully investigated. In the present study, we investigated differential susceptibilities in two different strains of micenamely, BALB/c (H-2d) and C3H/HeN (H-2k) mice. Likewise, we investigated the effects of ketotifen, an antiallergic drug, on the immune response against E. hortense infection. The worm recovery rate of the C3H/HeN mice was much higher than that of the BALB/c mice. The messenger ribonucleic acid (mRNA) expressions of interleukin (IL)-4 and IL-5 in the BALB/c mice were stronger than that of the C3H/HeN mice after E. hortense infection, but IL-1beta and tumor necrosis factor (TNF)-alpha expressions in the BALB/c mice were weaker than that of the C3H/HeN mice after E. hortense infection. The number of goblet cells and eosinophils increased after E. hortense infection in the BALB/c and the C3H/HeN mice. The worm recovery rate was higher and lasted longer in the ketotifen-treated mice in comparison to the untreated mice. Ketotifen suppressed the mRNA expression of IL-4 and IL-5 in the BALB/c mice, but did not in the C3H/HeN mice. The IL-1beta expressions were inhibited by ketotifen in the two strains, but TNF-alpha expression was inhibited in the C3H/HeN mice after ketotifen treatment. In addition, ketotifen inhibited the increase in eosinophils and goblet cells in varying degrees, depending on the strain. In summary, the immune sensitivity against E. hortense depends on the species of the host. The ketotifen treatment administered on the infected mice differently blocked the immune response against E. hortense infection.

Establishment of an allergic rhinitis model in mice for the evaluation of nasal symptoms

The purpose of our study was to establish a new model of allergic rhinitis in mice, eliciting symptoms such as sneezing, infiltration of eosinophils into the nasal mucosa, and antigen-specific IgE production. One of the major human T-cell epitopes in Cry j 1, an allergen of Japanese cedar pollen, is also a major murine T-cell epitope in B10.S mice. Thus we tried to establish an allergic rhinitis model in B10.S mice with Cry j 1 as the antigen. We sensitized B10.S mice subcutaneously with Cry j 1/alum three times at intervals of 1 week. Five weeks after the final sensitization, we challenged the mice by instilling Cry j 1 intranasally from the day after intranasal histamine pretreatment. Soon after, we counted the number of sneezes. We then evaluated the infiltration of eosinophils into the nasal tissues and also measured the serum levels of antigen-specific IgE antibody. In addition, we confirmed the effects of ketotifen fumarate and dexamethasone hydrochloride on these animals. In Cry j 1-sensitized B10.S mice, sneezes, eosinophil peroxidase (EPO) activity in nasal tissues, and Cry j 1-specific IgE clearly increased after intranasal histamine pretreatment and 5 days of continuous intranasal Cry j 1 challenge. Both ketotifen and dexamethasone inhibited the increase in sneezing, and dexamethasone also inhibited EPO activity and Cry j 1-specific IgE. Thus we succeeded in establishing a new model of allergic rhinitis in Cry j 1-sensitized B10.S mice, which exhibited sneezing, eosinophil infiltration into the nasal mucosa, and Cry j 1-specific IgE production.

Mast cell degranulation alters lymphatic contractile activity through action of histamine

OBJECTIVE

Mast cells reside in most tissues and in close association with blood vessels and nerves, areas where lymphatic vessels are also present. Mast cells and lymphatic vessels are two important players in the development of the inflammatory process. This study was designed to examine the effects of mast cell degranulation on the contractile activity of mesenteric lymphatic vessels.

METHODS

Lymphatic vessel contractile activity was assessed in vitro by video microscopy of the mesentery of cow's milk-sensitized guinea pigs upon application of beta-lactoglobulin and compared to the response measured in sham animals.

RESULTS

Application of 5-10 microM beta-lactoglobulin increased lymphatic vessel constriction frequency and decreased constriction amplitude (n = 12). This effect was not seen in sham-treated animals (n = 16) and was not due to an increased number of mast cells in the mesentery of the milk-sensitized animals, as revealed by histological examination. Two known mast cell-derived mediators, histamine and thromboxane A2, via stable mimetic U46619 also altered lymphatic pumping in a similar manner, but only pretreatment with the histamine H1 receptor antagonist pyrilamine (1 microM) could reduce the beta-lactoglobulin-induced response. The thromboxane A2 receptor antagonist, SQ 29548, and the 5-lipoxygenase inhibitor, caffeic acid, were without significant effect.

CONCLUSION

In the in vitro mesenteric preparation, mast cell degranulation altered lymphatic contractile activity via the release of a mediator suggested to be histamine and the subsequent activation of H1 receptors. This action could potentially interfere with the expected ability of lymphatic vessels to reduce edema during inflammation.

Brain histamine H receptor occupancy of orally administered antihistamines measured by positron emission tomography with (11)C-doxepin in a placebo-controlled crossover study design in healthy subjects: a comparison of olopatadine and ketotifen

AIMS

The strength of sedation due to antihistamines can be evaluated by using positron emission tomography (PET). The purpose of the present study is to measure histamine H(1) receptor (H(1)R) occupancy due to olopatadine, a new second-generation antihistamine and to compare it with that of ketotifen.

METHODS

Eight healthy males (mean age 23.5 years-old) were studied following single oral administration of olopatadine 5 mg or ketotifen 1 mg using PET with (11)C-doxepin in a placebo-controlled crossover study design. Binding potential ratio and H(1)R occupancy were calculated and were compared between olopatadine and ketotifen in the medial prefrontal (MPFC), dorsolateral prefrontal (DLPFC), anterior cingulate (ACC), insular (IC), temporal (TC), parietal (PC), occipital cortices (OC). Plasma drug concentration was measured, and correlation of AUC to H(1)R occupancy was examined.

RESULTS

H(1)R occupancy after olopatadine treatment was significantly lower than that after ketotifen treatment in the all cortical regions (P < 0.001). Mean H(1)R occupancies for olopatadine and ketotifen were, respectively: MPFC, 16.7 vs. 77.7; DLPFC, 14.1 vs. 85.9; ACC, 14.7 vs. 76.1; IC, 12.8 vs. 69.7; TC, 12.5 vs. 66.5; PC, 13.9 vs. 65.8; and OC, 19.5 vs. 60.6. Overall cortical mean H(1)R occupancy of olopatadine and ketotifen were 15% and 72%, respectively. H(1)R occupancy of both drugs correlated well with their respective drug plasma concentrations (P < 0.001).

CONCLUSION

It is suggested that 5 mg oral olopatadine, with its low H(1)R occupancy and thus minimal sedation, could safely be used an antiallergic treatment for various allergic disorders. Abbreviations histamine H(1) receptor (H(1)R), histamine H(1) receptor occupancy (H(1)RO), dopamine D(2) receptor (D(2)R), positron emission tomography (PET), blood-brain barrier (BBB), binding potential ratio (BPR), distribution volume (DV).

Emerging drugs for ocular allergy

Ocular allergy is a common condition that usually affects the conjunctiva of the eye and is, therefore, often referred to as allergic conjunctivitis. The severity of the disease can range from mild itching and redness, as seen in seasonal allergic conjunctivitis, to the more severe, sight-threatening forms such as vernal and atopic keratoconjunctivitis. The central mechanism in the pathogenesis of these diseases is IgE-mediated mast cell degranulation and activation of T lymphocytes, eosinophils and conjunctival structural cells. The pharmacotherapy of allergic conjunctivitis consists of several classes of drugs: antihistamines, mast cell stabilisers, dual-acting agents and corticosteroids. None of the available drugs completely abolishes the development of ocular allergy. For this reason, new topical antiallergic/anti-inflammatory agents are currently and continually under clinical trials. This review provides a background to ocular allergic diseases, the medical need for therapy and current and potential new treatments.

Anthrax lethal toxin induces ketotifen-sensitive intradermal vascular leakage in certain inbred mice

Bacillus anthracis lethal toxin (LT) is a bipartite toxin composed of protective antigen (PA) and lethal factor (LF). Injection of LT produces clinical signs characteristic of anthrax infection, including pleural edema and vascular collapse in various animal models. We utilized the classic Miles leakage assay to quantify vascular leakage in mice. LT injected intradermally induced leakage as early as 15 to 25 min in some inbred mouse strains, but not in others, whereas PA or LF individually did not induce leakage. A third component of anthrax toxin, edema factor, did not induce leakage alone or with PA. Leakage was quantified in eight mouse strains, and no correlation was found between sensitivity to intradermal leakage and sensitivity to the lethality of systemically administered LT. The leakage could be inhibited by ketotifen, an inhibitor of mast cell degranulation, but not by azelastine, a histamine receptor 1 antagonist, or by ketanserin, a serotonin 5-HT2A receptor antagonist. LT was cytotoxic to MC/9 mast cells (in vitro) by 7 h after toxin treatment but did not induce histamine release from these cells. Mast cell-deficient mice exhibited the leakage event and had no increased resistance to systemic LT. Human umbilical vein endothelial cells were resistant to LT over 12 h, with only 20% of cells succumbing by 24 h, suggesting that endothelial cell killing is not the cause of the rapid LT-mediated leakage event. We describe here a ketotifen-sensitive vascular leakage event induced by LT which is the most rapid in vivo or in vitro LT-mediated effect reported to date.

A structure–activity relationship study of compounds with antihistamine activity

A structure-activity relationship (SAR) analysis of H(1)-, H(2)- and H(3)-antihistamine activity was carried out and chromatographic data of 2-[2-(phenylamino)thiazol-4-yl]ethanamine, 2-(2-benzyl-4-thiazolyl)ethanamine, 2-(2-benzhydrylthiazol4-yl)ethanamine, 2-(1-piperazinyl- and 2-(hexahydro-1H-1,4-diazepin-1-yl)benzothiazole, 2-(1-piperazinyl)benzothiazole, 2-[4-(1-alkyl)piperidinyl]benzothiazole, 2-(N,N',N'-dimethylalkyl-1,2-ethanediamino)benzothiazole, 2[1-(4-aminopiperidinyl)]benzothiazole, 2-[2-phenyl-4-thiazolyl]ethanamine derivatives and selected H(1)- and H(2)-antihistamine drugs were obtained. NP TLC and RP2 TLC plates (silica gel NP 60F(254) and silica gel RP2 60F(254) silanized precoated), impregnated with a solution of aspartic acid (L-Asp) and a solution of an analogue of aspartic acid (propionic acid), were used in two developing solvents as H(1)-, H(2)- and H(3)-antihistaminic interaction models. The lipophilicity data of the examined compounds were obtained and used in the SAR assay. Biochromatographic tests using TLC plates impregnated with solutions of asparic acid or propionic acid were found to be a source of useful data for the qualitative analysis of compounds with different structures, demonstrating activity to histamine H(1)-, H(2)- and H(3)-receptors. The four presented discriminant models based on biochromatographic studies are an efficient tool in the SAR analysis for initial prediction of compound activity direction within histamine receptors.

Inhibition of granuloma-associated angiogenesis by controlling mast cell mediator release: role of mast cell protease-5

We investigated the role of mast cells in granuloma-associated angiogenesis in rat by using: (i) a mast cell membrane stabilizer, ketotifen; (ii) a mast cell depleting agent, compound 48/80. Moreover, we focused on the role of chymases, which exhibit proinflammatory and pro-angiogenic properties by using: (i) chymostatin, an inhibitor of chymase activity; (ii) a specific antisense oligonucleotide (AS-ODN) designed against rat mast cell protease-5 (rMCP-5), the most abundantly expressed chymase in the skin. The formation of granuloma was evaluated, as wet weight, 96 h after the subcutaneous implant of two lambda-carrageenin (1%)-soaked sponges on the back of male Wistar rats. Angiogenesis was evaluated as haemoglobin content in the granulomatous tissue and as level of tumour necrosis factor-alpha (TNF-alpha) in the exudates. A single injection of ketotifen (1-5-25 mg kg(-1) i.p.) significantly reduced granuloma formation by 31.6, 44.6 and 71.9%, and haemoglobin content by 17.0, 35.0 and 66.2%, suggesting that the release of mediator(s) from mast cells modulates the process. Chymostatin (5-10 nmol(-1) site(-1) day(-1)) reduced granuloma-associated angiogenesis by 57.3 and 70.0%. RT-PCR analysis showed that rMCP-5 mRNA amounts were significantly reduced by rMCP-5 AS-ODN (1.25-2.5-5.0 nmol site(-1)) by 69.5, 72.5 and 81.8%. In parallel experiments, rMCP-5 AS-ODN (1.25, 2.5, 5.0 nmol site(-1)) strongly reduced granuloma weight (26.1, 45.0 and 56.3%) and haemoglobin content (22.2, 50.4, 62.03%), suggesting that the observed effect is mediated through an antisense mechanism. In conclusion, these data suggest that: (i) inhibition of mast cell mediators release may represent a novel strategy to modulate angiogenesis; (ii) among the chymase family, rMCP-5 is a key promoter of angiogenesis in the rat.

Efficacy and safety of single- and multiple-dose ketotifen fumarate 0.025% ophthalmic solution in a pediatric population

Allergic conjunctivitis can seriously disrupt children's daily activities. This study assessed the efficacy (onset and duration of action) and safety of ketotifen fumarate 0.025% ophthalmic solution compared with vehicle placebo in pediatric subjects after single and multiple dosing. This was a double-masked, multicenter, fellow-eye, placebo-controlled, conjunctival allergen challenge trial. Eligible subjects (8-16-yr-olds) who produced a qualifying reaction to allergen were randomized to a single dose (one drop) of ketotifen fumarate in one eye and vehicle placebo in the fellow eye, followed by an allergen challenge at 15 min and 8 h post-dose. Subjects who had a qualifying reaction to allergen in the placebo-treated eye and a qualifying response to ketotifen in the active-treated eye following the single dose were re-randomized to a multiple-dose treatment period. They were instructed to instill one drop of ketotifen fumarate in one eye and placebo in the other eye twice daily for 4 wk. An allergen challenge was conducted 8 h after the last dose. The primary efficacy assessment was ocular itching, judged by the subject at 3, 7, and 10 min post-allergen challenge after single- and multiple-dose treatments. Other ocular signs and symptoms were assessed at 7, 10, and 15 min post-dose. A total of 133 subjects were randomized to single-dose treatment; 105 were evaluable for efficacy. Of these, 60 were re-randomized to multiple-dose treatment, and 55 were evaluable for efficacy. After single and multiple doses, ketotifen fumarate significantly inhibited ocular itching compared with placebo at all post-challenge timepoints (p < 0.001) and also significantly reduced hyperemia, chemosis, and lid swelling (p = 0.031). No drug-related systemic adverse events were reported, and ocular adverse events were comparable to placebo. No subject discontinued prematurely due to an adverse event. These results indicate that ketotifen fumarate 0.025% ophthalmic solution is an effective and safe treatment option for children with allergic conjunctivitis.

Perennial rhinitis in the under 4s: a difficult problem to treat safely and effectively? A comparison of intranasal fluticasone propionate and ketotifen in the treatment of 2-4-year-old children with perennial rhinitis

To compare the safety and efficacy of fluticasone propionate aqueous nasal spray (FPANS) and oral ketotifen in children aged 2-4 years with perennial rhinitis. A randomized, multicentre, double-blind, double dummy, placebo-controlled study. Paediatric patients between the ages of 2-4 years with perennial rhinitis. Rhinitis symptoms score (parent-rated), clinical evaluation of symptoms (investigator-rated) and adverse event profiles during the treatment period. Patients treated with FPANS had a significant reduction in both the total night-time rhinitis symptom assessment for weeks 4-6 (p-value 0.036), and the total daytime rhinitis symptom score over the same period (p-value 0.049). Generally, except for nasal itching/rubbing over weeks 1-3, the patients taking FPANS had lower recorded symptom scores for all individual symptoms measured. Nasal blockage, in particular, was significantly reduced over the 4-6 week period (p-value 0.027). The overall investigator-rated clinical evaluation showed substantial improvement or improvement in nine of 12 of the children taking FPANS compared with four of 14 taking ketotifen. Finally, there were no reports of serious adverse events, the incidence of drug-related adverse events was low and there was no statistical difference between the groups. FPANS may be an appropriate treatment to control the symptoms of rhinitis in children between 2 and 4 years old.

Efficacy and safety of ketotifen fumarate 0.025% in the conjunctival antigen challenge model of ocular allergic conjunctivitis

PURPOSE

To determine the duration of action of ketotifen 0.025% eye drops vs placebo taken as single or multiple doses in an allergen challenge model.

DESIGN

Two randomized, multicenter, double-masked, contralateral placebo-controlled studies, one a single-dose and one a multiple-dose study.

METHODS

Two conjunctival provocation tests (CPTs) were initially conducted to confirm reproducibility of subject responses in both studies. Subjects in study 1 (n = 87) received single doses of ketotifen in one eye and placebo in the other 15 minutes, 6 hours, and 8 hours before CPT. Subjects in study 2 (n = 85) received ketotifen or placebo once 8 hours before CPT. Single-dose efficacy results were used to further qualify a subject as a responder. Responders were re-randomized to a 4-week twice daily dosing regimen with a CPT 8 hours after the final dose. In both studies, ocular symptoms were assessed at three time points 3 to 15 minutes after challenge. There were no significant differences in adverse events between groups.

RESULTS

For both studies, ocular itching and vascular injection were significantly reduced (P <.003) at all time points after instillation of ketotifen, with a maximum reduction at 7 minutes postchallenge. In study 2, chemosis, tearing, and lid swelling were also assessed and were significantly reduced (P <.008) after instillation of ketotifen.

CONCLUSIONS

Ketotifen 0.025% eye drops were safe and statistically effective in preventing ocular itching, injection, and other signs and symptoms of allergic conjunctivitis at 15 minutes, 6 hours, and 8 hours after a single dose and at 8 hours after the final dose of a 4-week twice daily regimen.

Efficacy and safety of ketotifen eye drops in the treatment of seasonal allergic conjunctivitis

BACKGROUND

Ketotifen blocks histamine H(1) receptors, stabilises mast cells, and prevents eosinophil accumulation. These multiple, pharmacological mechanisms provided the rationale for assessing the efficacy and safety of ketotifen 0.025% eye drops in subjects with seasonal allergic conjunctivitis (SAC) in an environmental setting.

METHODS

This was a double masked, randomised, multicentre trial conducted in Australia. Subjects were randomly assigned to ketotifen fumarate 0.025% ophthalmic solution, placebo (as vehicle), or levocabastine hydrochloride 0.05% ophthalmic suspension, twice daily in each eye for a 4 week period. Subjects were assessed at follow up (days 5-8) and termination (days 25-31) visits. The primary efficacy variable was the responder rate, based on the subjects' assessment of global efficacy at the follow up visit.

RESULTS

519 subjects were randomised to treatment. At the follow up visit, the responder rate, based on subjects' assessment of global efficacy, was significantly greater in the ketotifen group (49.5%) than in the placebo group (33.0%) for subjects with a positive diagnostic test for pollen allergy (p = 0.02). The investigators' assessment of responder rates also showed that ketotifen was superior to placebo (p = 0.001). Ketotifen produced a significantly better outcome than levocabastine (p<0.05) for relief of signs and symptoms of SAC, at both the follow up and the termination visit. The type and frequency of adverse events were similar across treatment groups.

CONCLUSIONS

In an environmental setting, ketotifen fumarate 0.025% ophthalmic solution was well tolerated and effective in reducing the signs and symptoms of SAC, and in preventing their recurrence. Ketotifen consistently showed the best efficacy in comparison with both placebo and levocabastine. These results indicate that ketotifen eye drops are a valuable treatment option for this condition.

Role of mast cells and pro-inflammatory mediators on the intestinal secretion induced by cholera toxin

Recent data suggest that diarrhea caused by Vibrio cholerae involves a pro-inflammatory mediators release, such as cytokines, prostaglandin and nitric oxide. The aim of this study was to investigate the role of mast cells and their mediators in the intestinal secretion induced by cholera toxin. We examined the dose responses, time course and role of mast cells and pro-inflammatory mediators in cholera toxin intestinal secretory response, in vivo. Cholera toxin caused a dose-dependent secretion, in ligated small intestine loops, at 18 h. Rats treated with 48/80 compound or ketotifen had a significant decrease in the intestinal secretory response. Cholera toxin secretion was significantly reduced by an unspecific histamine/serotonin receptor antagonist, histamine receptor antagonist, phospholipase A2 and cyclooxygenase inhibitors, platelet-activating factor (PAF) receptor antagonists and TNF-alpha synthesis blockers. On the other hand, pretreatment with a specific serotonin receptor antagonist and lipoxygenase inhibitors failed to block this effect. Analysis of the intestinal fluid from rats injected with cholera toxin, revealed that cholera toxin induces the release of IL-1beta and TNF-alpha into fluid. The data suggest that, at least in part, mast cells are involved in cholera toxin-induced secretion, as well as point to the importance of histamine, prostaglandins, PAF, IL-1beta and TNF-alpha in this process.

A placebo-controlled comparison of ketotifen fumarate and nedocromil sodium ophthalmic solutions for the prevention of ocular itching with the conjunctival allergen challenge model

BACKGROUND

Ketotifen fumarate 0.025% ophthalmic solution and nedocromil sodium 2.0% ophthalmic solution are 2 topical antiallergic medications with different modes of action and efficacy profiles. Both solutions are indicated for ocular itching associated with allergic conjunctivitis.

OBJECTIVE

This study compared the efficacy, safety, and comfort of ketotifen fumarate 0.025% ophthalmic solution and nedocromil sodium 2.0% ophthalmic solution for the prevention of ocular itching, using the conjunctival allergen challenge (CAC) model.

METHODS

This was a single-center, double-masked, contralateral, randomized, placebo- and active-controlled CAC clinical trial. Subjects aged >10 years with a history of allergic hypersensitivity who responded to the CAC at screening visits 1 and 2 qualified for randomization at visit 3. At visit 3 (day 21) and visit 4 (day 35), subjects received 1 of 3 treatments: ketotifen, nedocromil, or placebo (artificial tears), randomized by eye. Allergen challenges were conducted at 5 minutes posttreatment dose (visit 3) and 12 hours posttreatment dose (visit 4). At each visit, subjects evaluated their ocular itching every 30 seconds for 20 minutes. At visit 4, subjects evaluated the comfort of the medication immediately after instillation, at 30 seconds after instillation, and at l, 2, 5, and 10 minutes after instillation. The subjects were also queried about overall eyedrop comfort by choosing from descriptive terms and about overall eyedrop preference based on comfort and perceived efficacy.

RESULTS

Eighty-five subjects were screened for this study. Fifty-nine (28 males, 31 females; mean age, 38.7 years) qualified and were randomized to receive study medications. Ketotifen-treated eyes experienced significantly less ocular itching induced by CAC than nedocromil-treated eyes and those that received placebo at both the 5-minute and 12-hour posttreatment allergen challenges (all P < 0.05). Nedocromil-treated eyes showed no statistical or clinical differences from placebo at any time point. Ketotifen-treated eyes showed no differences in comfort from those that received placebo but were significantly more comfortable than nedocromil-treated eyes at 1, 2, 5, and 10 minutes after instillation (all P < 0.05). On the basis of comfort and subjective efficacy, 60% of subjects preferred ketotifen, 21% preferred nedocromil, and 19% preferred placebo.

CONCLUSION

Ketotifen was significantly more effective and comfortable than nedocromil at both 5 minutes and 12 hours after administration in this CAC model.

Forsythia fructus inhibits the mast-cell-mediated allergic inflammatory reactions

Mast cells are key as effector cells in the early phase allergic inflammation and in diverse immunological and pathological processes. Forsythia fructus (F. fructus) has used as a traditional medicine for inflammatory diseases. In the present study, we determined the effect of F. fructus extracts on compound 48/80-induced paw oedema and vascular permeability in vivo. In addition, we investigated in vitro whether F. fructus has inhibitory effects on compound 48/80-induced histamine releases from rat peritoneal mast cells (RPMC), and on phorbol 12-myristate 13-acetate (PMA) plus A23187-induced tumor necrosis factor-alpha (TNF-alpha) releases from human mast cells (HMC-1). In mice orally administrered F. fructus (100 microg/g) for 1 h, compound-48/80-induced oedema and vascular permeability were significantly reduced rather than those receiving intravenous injection of ketotifen, mast cell stabilizer. F. fructus dose-dependently inhibited the histamine release induced by compound 48/80 from RPMCs. Moreover, F. fructus had no cytotoxic effects on cell viability and had inhibitory effects on TNF-alpha secretion from HMC-1. These results suggest that F. fructus is a potential herb medicine for treatment of inflammatory diseases through downmodulating mast cell activation.

Inhibitory effects of ketotifen on eotaxin-dependent activation of eosinophils: consequences for allergic eye diseases

BACKGROUND

The aim of this study was to investigate the effects of ketotifen on different parameters of human eosinophil functions, namely chemotaxis, oxidative metabolism and mediator release, induced after activation.

METHODS

Eosinophils from hypereosinophilic patients or normal donors were purified by Percoll gradient and the magnetic cell separation system. Chemotaxis was studied using the Boyden chamber technique using three potent chemoattractants: formyl-methionine-leucine-phenylalanine (fMLP), interleukin (IL)-5 and eotaxin. Oxidative metabolism was determined by a luminol-dependent chemiluminescence assay after activation with eotaxin or secretory immunoglobulin A (sIgA). The release of eosinophil cationic protein (ECP) and eosinophil derived neurotoxin (EDN) was measured by radioimmunoassay after activation with sIgA.

RESULTS

At pharmacologically active concentrations and in a dose-dependent manner, ketotifen significantly inhibited the chemotaxis of eosinophils to fMLP, IL-5 and eotaxin. The production of reactive oxygen species induced by eotaxin and sIgA was decreased by ketotifen, showing a more pronounced effect when cells were activated by eotaxin. Activation by sIgA resulted in ECP and EDN release, which was partially inhibited by ketotifen.

CONCLUSIONS

Through inhibition of chemotaxis, ketotifen might limit the number of eosinophils at the inflammation site during allergic reaction. Furthermore, inhibition by ketotifen of main inflammatory mediators release suggests a potential role of the drug in limiting the pathological potential of eosinophils.

Effects of ketotifen 0.025% and lodoxamide 0.1% on eosinophil infiltration into the guinea pig conjunctiva in a model of allergic conjunctivitis

The effects of ketotifen and lodoxamide on eosinophil infiltration were assessed in a guinea pig model of allergic conjunctivitis. The two active treatments were coded in this masked study in which 30 male guinea pigs, sensitized to chicken egg albumin (ovalbumin), were randomly assigned to one of three groups: Group 1, instillation of 0.9% NaCl into the conjunctival sac of both eyes; Group 2, instillation of 0.025% ketotifen into the left eye and 0.9% NaCl into the right eye; Group 3, instillation of 0.1% lodoxamide into the left eye and 0.9% NaCl into the right eye. Ovalbumin was administered topically to each eye, except in Group 1 where it was only applied to the left eye. (111)In-oxine labeled eosinophils were injected into the jugular vein of each guinea pig; the animals were sacrificed 17 hours after ovalbumin had been applied. The level of radioactivity in the ketotifen- and lodoxamide-treated eyes was approximately 60% of that in the saline-treated eyes. Moreover, the mean level of radioactivity in the ketotifen- and lodoxamide-treated eyes was comparable with the mean level of radioactivity in the saline-treated eye of Group 1, which had not been exposed to allergen. These results indicate that the therapeutic effects of ketotifen and lodoxamide in allergic conjunctivitis may be partly mediated by an inhibitory effect on eosinophils.

Ketotifen fumarate and olopatadine hydrochloride in the treatment of allergic conjunctivitis: a real-world comparison of efficacy and ocular comfort

This 3-week prospective, randomized, double-masked, parallel-group study compared ketotifen fumarate 0.025% ophthalmic solution and olopatadine hydrochloride 0.1% ophthalmic solution in 66 patients with seasonal allergic conjunctivitis. The drugs were instilled twice daily. Signs and symptoms were assessed on days 5 (visit 2) and 21 (visit 3). Other efficacy variables were the responder rate (patients with excellent or good global efficacy on days 5 and 21) and patient and investigator ratings of global efficacy. Comfort was evaluated immediately after instillation of the first drop and at each follow-up visit. The frequency of adverse events was the safety assessment. The responder rate was higher with ketotifen than with olopatadine on day 5 (72% vs 54% for patient assessment, 88% vs 55% for investigator assessment) and day 21 (91% vs 55%, 94% vs 42%). Global efficacy ratings were higher with ketotifen, and severity scores for hyperemia and itching were significantly lower. Both drugs elicited comparable comfort ratings. The most common adverse events were burning/stinging and headache.

A randomized comparison of chloroquine and chloroquine plus ketotifen in the treatment of acute, uncomplicated, Plasmodium falciparum malaria in children

The increasing resistance of Plasmodium falciparum to chloroquine (CQ) has created urgent needs for the evaluation of alternative antimalarial drugs that are effective, safe, readily available and affordable. Ketotifen, a histamine H(1)-receptor antagonist that reverses CQ resistance in P. falciparum in vitro, may potentially enhance the effects of CQ in vivo. The effects of oral treatment with CQ alone (30 mg/kg base given over 3 days) were compared with those of this CQ regimen combined with ketotifen fumarate (0.25 mg at presentation followed by 0.125 mg/kg every 8 h for 5 days). The subjects were 145 children aged 1-10 years who were suffering from acute, symptomatic, uncomplicated, P. falciparum malaria: 74 given CQ alone and 71 given CQ plus ketotifen (CQK). Although the mean fever-clearance time was significantly shorter following treatment with CQK than after treatment with CQ alone, all other therapeutic responses were similar in the two treatment groups. Among siblings in whom there was clustering of infections, the likelihood of cure was also similar in the two treatment groups. Retreatment of 17 CQ-treatment failures with CQK produced a cure in six children, and retreatment of 22 CQK-treatment failures with CQK produced a cure in eight children. Retreatment of all drug failures with a combination of amodiaquine plus pyrimethamine-sulfadoxine resulted in complete clearance of parasitaemia and symptoms within 2-3 days and a cure 'rate' of 100% on day 28. The prevalences and intensities of gametocytaemias on day 3 or days 3, 7 and/or 14 combined were similar in the two groups. Adverse drug reactions were always tolerable, and limited to pruritus, gastro-intestinal disturbances, drowsiness and weight gain; the latter two adverse effects were significantly more frequent in those treated with CQK than in those given CQ alone. Haematological and biochemical parameters were not adversely affected by either treatment regimen. The findings indicate that - at least at the dosing regimen used in the present study and among children with acute, uncomplicated, P. falciparum malaria from Ibadan - the addition of ketotifen to CQ produced little or no significant enhancement of the antimalarial effect of CQ.

The anti-allergic effects of a cromolyn sodium-chlorpheniramine combination compared to ketotifen in the conjunctival allergen challenge model

PURPOSE

To compare the inhibitory effects of a topical combination product, cromolyn sodium (DSCG) 4% with the antihistamine, chlorpheniramine, with those of topical ketotifen 0.05% on the clinical allergic reaction induced by the conjunctival allergen challenge (CAC).

METHODS

Ten allergic but non-active patients were challenged in both eyes with increasing doses of specific allergen to obtain a positive bilateral reaction (visit 1). They were then rechallenged after 1 week to confirm the allergic threshold dose response (visit 2). After 2 weeks, a third CAC was performed bilaterally 30 minutes after topical application of DSCG-chlorpheniramine in one eye and ketotifen in the contralateral eye in a double-masked fashion (visit 3). Clinical signs and symptoms were registered 5, 10, 15, and 20 minutes after challenge using the standard scoring system. Tear cytology was performed 30 minutes after challenge.

RESULTS

Comparing the two drug effects at visit 3, DSCG-chlorpheniramine was shown to be superior to ketotifen at all time points for itching (p < 0.01) and at 5 minutes for redness (p < 0.01). For the total signs score, DSCG-chlorpheniramine was shown to be superior to ketotifen at all time points (p < 0.01), and at 10 and 15 minutes for the total symptoms score (p < 0.05). Compared to visit 2, DSCG-chlorpheniramine significantly lowered itching (p < 0.001) and redness (p < 0.05) at 5, 10, 15, and 20 minutes after challenge. Ketotifen significantly lowered itching at 5 and 10 minutes (p < 0.001) and redness at 5, 10, and 15 minutes (p < 0.05). Both drugs reduced the total number of cells evaluated by tear cytology during the early-phase reaction (p < 0.05).

CONCLUSIONS

DSCG-chlorpheniramine was found to be more effective than ketotifen at preventing itching and redness in the CAC model.

The effect of ketotifen on inflammatory markers in allergic conjunctivitis: an open, uncontrolled study

BACKGROUND

The efficacy and safety of ketotifen eye drop treatment in allergic conjunctivitis (AC) management is perfectly known by several studies, but the mechanism of action at the biochemical levels is poorly understood so we decided to perform an open, uncontrolled study in order to investigate the effect of the topical administration of ketotifen fumarate 0.05% on biochemical markers of inflammation on conjunctival cells in patients with AC.

METHODS

Nineteen patients with symptoms and signs of AC (itching, discharge, burning, redness, increase in the watery discharge, swelling and follicles) and with a history of allergy were prescribed with two daily instillation of one drop of eyewash ketotifen fumarate 0,05% in both eyes during thirty days. They were studied by measuring clinical and immunologic parameters.

RESULTS

Ketotifen fumarate treatment significantly reduced the total symptoms and signs score for each patient as well as each symptoms and signs at all time points compared with day 0 (p < 0.0001 and p < 0.016, respectively). Although the percentage of HLA-DR+ epithelial cells diminished only in 58% of patients, the numbers of CD29+ and eotaxin+ epithelial cells dropped significantly in 68% and 73 % of them (p < 0.0062 and <0.0082, respectively) as a consequence of the treatment. In 9 out of 19 patients a simultaneous decrease in the percentage of epithelial cells positive for CD29 and eotaxin was observed.

CONCLUSION

Ketotifen besides the well-known effect in reducing signs and symptoms of AC significantly diminished production of eotaxin and expression of CD29 by epithelial cells in patients with seasonal AC.

Onset and Duration of Action of Ketotifen???0.025%???and???Emedastine???0.05% in Seasonal Allergic Conjunctivitis

OBJECTIVE

To compare the efficacy, onset and duration of action, and the safety of ketotifen fumarate 0.025% ophthalmic solution and emedastine difumarate 0.05% ophthalmic solution in subjects with seasonal allergic conjunctivitis (SAC) induced by allergen exposure, using the Vienna Challenge Chamber model.

DESIGN AND SETTING

This was a double-masked, randomised, comparative, crossover study conducted at an allergy outpatient clinic in Austria.

STUDY PARTICIPANTS

Subjects with an allergy to grass pollen were exposed to the allergen in a pollen chamber for 4 hours, followed by a 3-hour break and then a second exposure for 3 hours.

INTERVENTIONS

Study participants were randomised to a treatment sequence (ketotifen followed by emedastine or emedastine followed by ketotifen), receiving 1 drop per eye of ketotifen or emedastine 2 hours after the initial allergen exposure in the pollen chamber.

OUTCOMES

Individual and composite ocular, individual and composite nasal, and total (ocular + nasal) symptom complex scores were determined by repeated exposure to allergen 0-2 hours and 5-8 hours after dosing. Onset of action was defined as the time to the first observation of a 20% reduction from baseline in the composite ocular symptom score.

RESULTS

All 37 subjects enrolled completed the study. The median time to onset of action was 15 minutes for ketotifen and 30 minutes for emedastine. This difference was significant using the generalised linear model (p = 0.048), but not for the log-rank test analysis. In the initial 2 hours post dose, ketotifen provided significantly greater relief of both composite ocular symptoms (p = 0.026) and total symptom complex (p = 0.014). Both medications were effective in reducing symptoms 5 to 8 hours after dosing. No adverse events were reported for either treatment.

CONCLUSIONS

In the Vienna Challenge Chamber model, ketotifen and emedastine both effectively alleviated ocular symptoms of SAC after single-dose administration. Ketotifen had a faster onset of action and provided better symptom relief than emedastine during the first 2 hours after dosing. The rapid onset of action and symptom control make ketotifen a valuable treatment for SAC.

Determination of ketotifen and its conjugated metabolite in human plasma by liquid chromatography/tandem mass spectrometry: application to a pharmacokinetic study

A sensitive and specific liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed for the investigation of the pharmacokinetics of ketotifen and its major metabolite, ketotifen N-glucuronide, in human plasma. The plasma samples were treated by liquid-liquid extraction and analyzed using LC/MS/MS with an electrospray ionization interface. Diphenhydramine was used as the internal standard. The method had a lower limit of quantitation of 10 pg/mL for ketotifen, which offered increased sensitivity, selectivity and speed of analysis, compared with existing methods. The intra- and inter-day precision were measured to be below 8.2% and accuracy between -2.4% and 3.4% for all QC samples. Incubation of the plasma samples with beta-glucuronidase allowed the quantitation of ketotifen N-glucuronide. This quantitation method was successfully applied to a pharmacokinetic study of ketotifen and its major metabolite after oral administration of 2 mg ketotifen fumarate to 16 healthy volunteers.

Pharmacokinetics of ketotifen fumarate after intravenous, intranasal, oral and rectal administration in rabbits

The pharmacokinetics of ketotifen fumarate (KF) was examined after administration in rabbits through four different routes (intravenous, intranasal, oral and rectal). The time-course of the plasma concentration of KF after intravenous administration (1 mg/kg dose) fitted a two-compartment open model. KF was rapidly absorbed and showed a high plasma concentration within 0.33 h after intranasal administration. The absolute bioavailability of KF after intranasal administration was 66%. After oral administration at a dose of 1 mg/kg, the plasma concentration of KF was below the detection limit of HPLC analysis. Even at 5 mg/kg, the value of the area under the plasma concentration-time curve (AUC) after oral administration of KF was significantly lower than that after intranasal administration of 1 mg/kg. Oral bioavailability was only 8%. The very low bioavailability of KF after oral administration might be due to the first-pass effect in the liver. We also prepared suppositories containing KF (1 mg/kg) for rectal administration in rabbits. After rectal administration, KF was rapidly absorbed and its bioavailability was 34%. These results indicated that the intranasal route appears the most effective for administering KF, and that rectal administration may be superior to oral administration in terms of bioavailability.

Topical immunopharmacology of ocular allergies

PURPOSE OF REVIEW

To review the histamine-1 receptor antagonists, mast cell blockers and natural agents with such actions that can be used for the topical treatment of ocular allergies.

RECENT FINDINGS

Increasing evidence indicates that some histamine-1 receptor antagonists have additional actions to inhibit secretion of inflammatory mediators, especially cytokines, from ocular mast cells and other cell types. Emerging information suggests that such actions may be through regulation of intracellular calcium ion levels of NF-kappaB activation.

SUMMARY

A number of available drugs and natural non-prescription agents may have anti-histaminic and anti-inflammatory actions.

Ocular allergy guidelines: a practical treatment algorithm

The treatment of ocular allergy requires a better understanding of the spectrum of clinical disorders involving various components of the immune system, and of interactions at the conjunctival surface. The immune response focuses primarily on the different levels of activity of Th2 lymphocytes and various other immune cells associated with allergic disorders, including mast cells, eosinophils, fibroblasts, and epithelial and endothelial cells. Ocular allergic disorders include seasonal allergic conjunctivitis (SAC), perennial allergic conjunctivitis (PAC), vernal keratoconjunctivitis (VKC), giant papillary conjunctivitis (GPC) and atopic keratoconjunctivitis (AKC), which, through immunopathological and molecular immunological techniques, can all be better appreciated as being part of a larger spectrum of an atopic disease state. In SAC, pathological changes, such as increased mast-cell activation, the presence of migratory inflammatory cells, and early signs of cellular activation at the molecular level, are minimal. In PAC, these changes are more pronounced in line with the increased duration of allergenic stimulation. In more chronic forms of allergic conjunctivitis, such as VKC in children and AKC in adults, the following changes are evident: a persistent state of mast cell, eosinophil and lymphocyte activation; noted switching from connective-tissue to mucosal-type mast cells; increased involvement of corneal pathology; and follicular development and fibrosis. The treatment of acute and more chronic forms of allergic conjunctivitis has focused in the past on symptomatic relief of symptoms, but with a better understanding of the mechanisms involved we can now provide interventional therapeutic strategies and symptomatic relief. Our advances in the basic understanding of these conditions are providing the foundation for guidelines that improve the ocular health of patients with ocular allergies.