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Anti-oedematous action of some H1-receptor antagonists.

The oedema disk technique was used to study the effects of orally administered H1-receptor antagonists (cetirizine, chloropyramine, clemastine, cyproheptadine, dimethindene, loratadine, mequitazine and terfenadine) on the inflammation induced with capsaicin or croton oil in the mouse ear, and the effect of topically applied dimethindene maleate gel on the inflammation induced with croton oil in the mouse ear. In rats of the Wistar strain, oedema was induced in the hind paw by the subplantar injection of dextran or compound 48/80. Preliminary antihistamine treatment inhibited the development of oedema in the mouse ear, and of oedema in the rat paw, to statistically significant extents, in a dose-dependent manner. In all experiments, the most potent drugs were loratadine and cyproheptadine.

Animals↗

Acetylcholine mediation of the contractile response to histamine in human bladder detrusor muscle.

In Krebs solution, histamine evokes in human bladder detrusor muscle strips a dose-dependent contractile response which consists of two pharmacologically distinct responses: a high-sensitivity response evoked at 0.4-2 microM histamine, which is potentiated by neostigmine (0.1 microM) or blocked by atropine (0.1 microM) or ranitidine (1 microM); a low-sensitivity response evoked at 4-40 microM histamine and blocked by dimethindene or diphenhydramine. These findings suggest that the contractile response to low doses of histamine is mediated by acetylcholine released from a site proximal to the muscle. This effect of histamine seems to be mediated by a site which is insensitive to the H1 antagonists dimethindene and diphenhydramine but blocked by the H2 antagonist ranitidine.

Acetylcholine↗

Influence of the histaminergic system on opiate-induced neurosecretion and behaviour.

The influence of the histaminergic system on fentanyl (Fe)-induced growth hormone (GH) and prolactin (PRL) release as well as on Fe-induced increase of noradrenaline (NA) plasma levels has been studied in male volunteers. These volunteers received, according to a randomized block design, different pretreatments: the H1-antagonist dimethindene (Di) (0.1 mg/kg i.v.), or the H2-antagonist cimetidine (Ci)(5 mg/kg i.v.), or a combination of dimethindene and cimetidine (Di + Ci), or saline. The PRL increase caused by Fe (0.2 mg/70 kg) was not altered by pretreatment with the H1-antagonist Di, the H2-antagonist Ci, or the combination of both. The increase of NA plasma levels after Fe also was not modified by the histamine antagonists. In contrast, the maximum GH increase after Fe was blunted by the combination of Ci and Di, but not by either Ci or Di alone. These results suggest an involvement of the histaminergic system in opiate-induced GH-release.

Adult↗

Anti-inflammatory efficacy of topical preparations with 10% hamamelis distillate in a UV erythema test.

In 40 volunteers the efficacy of three lotions with 10% hamamelis distillates from different suppliers, two vehicles, dimethindene maleate 0.1% gel, hydrocortisone 1% cream and hydrocortisone 0.25% lotion were investigated in a modified UV erythema test with three UV dosages (1.2, 1.4 and 1.7 MED). The test preparations were applied occlusively over a 48-hour period following irradiation. Chromametric measurement of redness and visual assessment were performed 24, 48 and 72 h after induction of erythema. The hydrocortisone formulations were most effective in erythema suppression. An anti- inflammatory effect was noted for all three hamamelis lotions as well as for the vehicles. A significantly greater suppression of erythema than seen with the vehicles was noted for one of the hamamelis lotions at 1.4 MED. The efficacy of the antihistamine dimethindene maleate did not surpass the hamamelis lotions or the vehicles. Even though the differences between the hamamelis lotions were slight, it was possible to make an objective selection of the best hamamelis distillate for aftersun purposes.

Administration, Topical↗

[Separation of dimetinden enantiomers in drugs by means of capillary isotachophoresis].

Capillary isotachophoresis was employed to separate and determine dimethinden enantiomers in various dosage forms. Several types of chiral selectors were tested in various electrolyte systems of different composition and different pH. The optimal leading electrolyte was composed of 10 mmol/l potassium acetate and acetic acid to achieve pH 4.8 with an addition of 4 mmol/l carboxyethyl-beta-cyclodextrin as the chiral selector and 0.2% of methylhydroxyethylcellulose (m-HEC) to suppress the electroosmotic flow. The terminating electrolyte was betaalanine of a concentration of 5 mmol/l. The evaluation included the precision, correctness, linearity, robustness, and selectivity of the elaborated ITP method. The pretreatment of the sample prior to analysis consisted in the dissolution and dilution of the appropriate dimethinden-containing dosage form with demineralized water to achieve the required concentration. Such a pretreated sample was directly dosed into the apparatus.

Dimethindene↗

Evaluation of the anti-oedematous effects of some H1-receptor antagonists and methysergide in rats.

A combined method was used for a comparative study of some H1 and H2 antagonists and methysergide. In male rats of the Wistar strain weighing 130 +/- 5 g, oedema was induced in the hind paw by the subplantar injection of zymosan, and simultaneously in the ear by the application of croton oil to the inner surface of the ear. Intraperitoneally orally administered H1 antagonists (dimethindene, clemastine, cyproheptadine, astemizole, cetirizine, loratadine and terfenadine) inhibited the oedema to a statistically significant extent, in a dose-dependent manner. Outstanding inhibition was observed after simultaneous administration of the antiserotonin methysergide with dimethindene, clemastine, loratadine or cetirizine.

Animals↗

The suppression of olfactory bulbectomy-induced muricide by antidepressants and antihistamines via histamine H1 receptor blocking.

The effects of antidepressants [(+)-oxaprotiline, (-)-oxaprotiline, imipramine, maprotiline, and trazodone] and antihistamines (mepyramine, dimethindene, ketotifen, methapyrilene, and antazoline) on muricidal behaviour in olfactory bulbectomized rats were investigated. All drugs except for dimethindene, which only minimally passes across the blood-brain barrier, suppressed muricide. The drugs which have high affinity for histamine H1 receptor showed potent suppressive effect on muricide. It is suggested that the central histaminergic system is involved via H1 receptors in the expression of muricide in olfactory bulbectomized rats.

Aggression↗

H1-antagonism improves intestinal mucosal pH and heart function in porcine hypodynamic endotoxic shock.

Porcine hypodynamic shock was induced by continuous infusion of 5 micrograms lipopolysaccharide/kg per hour. This resulted in a decrease of cardiac output from baseline values of 3.5 +/- .9 L/min to 1.5 +/- .8 L/min and a reduced left ventricular stroke work index in the endotoxin-group (n = 6 animals). Pretreatment with the H1-antagonist dimethindene (2 mg/kg) in a second group (n = 6) significantly prevented these effects. Furthermore animals pretreated with the H1-antagonist showed a stable mean arterial blood pressure, whereas the control endotoxin-treated group revealed a drastic reduction in mean arterial blood pressure (99 +/- 4.7 mmHg versus 65.8 +/- 10 mmHg after 240 min, respectively). Pulmonary function and systemic vascular resistance were not ameliorated by the H1-antagonist in hypodynamic shock. Gastrointestinal mucosal pH (pHi), which indicates oxygenation of the mucosa, was decreased by endotoxin-infusion (7.45 +/- .32 baseline value to 6.92 +/- .24 after 120 min). This parameter as well as base excess values and lactate levels were significantly improved by dimethindene-pretreatment (p < .05). These results may indicate a beneficial effect of H1-antagonist-pretreatment on endotoxin-induced deterioration of the microcirculation. Furthermore our results clearly demonstrated that only pretreatment before endotoxemia with H1-antagonism is effective, since infusion of H1-antagonist in hypodynamic shock 45 min after addition of endotoxin (n = 6 animals) did not improve the cardiovascular system or the microcirculation.

Animals↗

The role of H1- and H2-receptors in the effect of compound 48/80 in the asphyxiation and body temperature of mice.

Contribution of histamine H1- and H2-receptors to the effect of compound 48/80, a potent histamine releaser, upon asphyxiation and body temperature in mice was investigated in the present experiments. Compound 48/80 showed an apparent protective potency against hypoxia and significantly prolonged the latencies for convulsions and death in a dose-dependent manner. Compound 48/80 also decreased the body temperature, which was in relation with the antihypoxic effect. Both the H1-receptor antagonist, dimethindene, and the H2-receptor antagonist, ranitidine, attenuated the hypothermic effect of compound 48/80, indicating the involvement of central histamine through both the H1- and H2-receptors. Ranitidine had no effect on the protective effect of compound 48/80 against hypoxia-induced lethality, whereas dimethindene completely antagonized it. These results suggest that the protective effect of compound 48/80 against hypoxia is mediated through histamine H1-receptors and is not related to its ability to induce hypothermia.

Animals↗

Spectrophotometric determination of some antihistaminic drugs using 7,7,8,8-tetracyanoquinodimethane (TCNQ).

A simple and sensitive spectrophotometric method is suggested for analysis of 3 antihistaminic drugs, acrivastine (I), mequitazine (II), and dimethindene maleate (III). The method is based on reaction of the drugs with 7,7,8,8-tetracyanoquinodimethane (TCNQ) in acetonitrile to form highly stable colored products that are measured at 750, 766, and 844 nm for I and II, and 480 and 618 nm for III. Beer's law is obeyed in the ranges of 5-60 microg/mL for 1, 5-50 microg/mL for II, and 10-70 microg/mL for III. The optimum assay conditions and their applicability to the determination of the cited drugs in pharmaceutical formulations are described. The method is statistically analyzed as compared with the European Pharmacopoeia (2001) method for the analysis of dimethindene maleate and reference methods for acrivastine and mequitazine drugs revealing good accuracy and precision.

Acetonitriles↗

[Antipruritic effect of antihistaminic and local anesthetic topical agents after iontophoretic histamine stimulation].

No adequate topical therapy is available for pruritus. As little is known about the local influence of antihistamines and topical anaesthetics on the pruritic effect of histamine, we studied these agents in 12 volunteers. The antipruritic effect of 15-min topical application of dimethindene maleate (Fenistil gel) and different agents (Optiderm, EMLA, Xylocaine-Salbe 5%) on subsequent focal histamine stimulus (20 mC) given by iontophoresis was evaluated. The results were compared with those of pretreatment with the corresponding placebo creams and observations on skin. Wheal and flare areas were evaluated planimetrically. Itch or pain ratings were entered on a scale every minute over a 24-min period. The examination also comprised alloknesis, i.e. elicitation of perifocal itch sensation by usually non-itch-inducing (e.g. mechanical) stimuli. Remarkably, all topically applied substances, regardless of antihistaminic or anaesthetic potential, reduced the area of alloknesis significantly. This is likely to be a result of diminished excitability of the cutaneous mechanoreceptors. Itching was significantly reduced by all active substances, including the placebo cream corresponding to Optiderm, which might be due to the presence of urea.

Adult↗

The role of histamine H1 receptors in the thermoregulatory effect of morphine in mice.

Morphine is known to release histamine from mast cells and increase the turnover of neuronal histamine. It is also known that histamine receptors mediate some of the morphine effects. The contribution of histamine H1 and H2 receptors to the thermoregulatory effect of morphine in mice was investigated in the present experiments. Morphine produced a hypothermic effect, especially at the dose of 10 mg/kg. Although the histamine H1 receptor antagonist, dimethindene (0.1 mg/kg, i.p.), attenuated the hypothermic effect of morphine (10 mg/kg), a histamine H2 receptor antagonist, ranitidine (100 mg/kg, i.p.), had no effect. These results suggest that the hypothermic effect of morphine in mice is mediated, at least partly, through histamine H1 receptors.

Animals↗

Semisynthetic chondroitins as chiral buffer additives in capillary electrophoresis.

Chemically oversulfated galactosaminoglycans with potential as therapeutic agents (inhibitors of human leukocyte elastase) were tested as chiral selectors in capillary electrophoresis of basic racemates. The high anionic character of these compounds provides them with anodic mobility in acidic buffer; using uncoated capillaries, the enantioresolution of racemic basic drugs was obtained at pH 2.5. Dimethindene, chloroquine and chlorpheniramine were enantioresolved applying negative voltage (-15 kV) while the other analytes (propranolol, pindolol, tetrahydrozoline and cloperastine) exhibited catodic migration. The addition of organic solvents to the running buffer was evaluated in order to increase the resolution; methanol provides the best results and in general, baseline separation of the analytes was reached. The studied oversulfated mucopolysaccharide, shows the same ionic character of heparin but presents different stereochemistry and sites of sulfation. A comparison with heparin, used in the same acidic conditions, may underline the role of ionic, spatial and steric features of glycosaminoglycans in the enantiorecognition.

Anions↗

Effect of oral antihistamine premedication on mivacurium-induced histamine release and side effects.

In this randomized, double-blind, placebo-controlled study, we have examined histamine release, haemodynamic and cutaneous effects of mivacurium administered in low (0.105 mg kg-1 = 1.5 x ED95) and high (0.21 mg kg-1 = 3 x ED95) doses and assessed if oral pretreatment with H1/H2 antagonists would blunt the effects of mivacurium-induced histamine release. Patients received either ranitidine 300 mg and dimethindene 0.1 mg kg-1 (H1 blocker) or placebo, orally 1 h before induction of anaesthesia. Twelve patients were allocated to each group. Although plasma concentrations of histamine increased significantly in three patients in the placebo group given low-dose mivacurium, the mean value for the group was unchanged. Plasma concentrations of histamine increased significantly in five patients in the placebo group after high-dose mivacurium and the mean value was increased. There was no consistent correlation between haemodynamic changes, cutaneous manifestations and histamine concentrations. Significant cardiovascular reactions occurred in six patients in the placebo groups and in only one patient treated with antihistamines.

Adolescent↗

The effect of antiallergic intranasal formulations on ciliary beat frequency of human nasal epithelium in vitro.

The nasal mucociliary clearance is an important defense mechanism of the upper respiratory tract. It is known to be influenced by many pharmacologic substances. We investigated the effects of three topical intranasal antiallergic formulations containing disodium cromoglycate (DNCG), dimethindene maleate (DMM), and azelastine-HCL (AZL) on nasal ciliary beat frequency (CBF) in vitro. Nasal ciliated cells were harvested from 16 healthy volunteers. Cells were diluted 1:10 in culture medium and incubated with a placebo formulation (PLAC), containing 0.022% benzalkonium chloride, which was part of all formulations, a registered 2% formulation of DNCG, a 0.1% formulation of DMM, and a registered 0.1% formulation of AZL. After an incubation period of 20 min, CBF was registered by a photoelectric measurement device. Under control conditions (CONTROL), CBF was 11.4 +/- 1.3 Hz. PLAC reduced CBF to 9.7 +/- 2.3 Hz (NS). DNCG reduced CBF to 9.7 +/- 2 Hz (NS). DMM reduced CBF to 7.2 +/- 1.7 Hz (P < or = 0.05 vs CONTROL, NS vs PLAC), and AZL reduced CBF to 0.9 +/- 1.8 Hz (P < or = 0.001 vs CONTROL, P < or = 0.001 vs DNCG, P < or = 0.001 vs PLAC). In conclusion, a possible influence of antiallergic intranasal formulations on nasal ciliary function has to be considered in clinical application.

Anti-Allergic Agents↗

Experimentally induced pruritus and cutaneous reactions with topical antihistamine and local analgesics in atopic eczema.

We investigated the antipruritic effect of a 15-min application of dimethindene maleate (Fenistil gel) and other local analgesics (Optiderm, EMLA, Xylocain ointment 5%) on subsequent focal histamine stimulus (20 mC) given by iontophoresis in 12 patients suffering from acute atopic eczema (AE). The results were compared to histamine after pretreatment with the respective placebo and to non-pretreated skin. Wheal and flare areas were planimetrically evaluated. Itch or pain ratings were performed over a 24-min period using a rating scale. The examination also comprised alloknesis, i.e. induction of a perifocal itch sensation by a non-itching mechanical stimulus. None of the antihistaminic and anaesthetic agents reduced the itch intensity significantly. Three of the AE patients had a total lack of alloknesis. We conclude that these substances, when applied for 15 min, are not sufficiently effective in atopic skin suppressing histamine-induced reactions under experimental conditions. The diminished elicitation of alloknesis in these patients may be a result of central nervous system alteration.

Administration, Topical↗

The role of histamine H1-receptors in the anticonvulsive effect of morphine against maximal electroconvulsive shock in mice.

Morphine is known to release histamine from mast cells. It is also known that histamine receptors mediate some of morphine's effects on the central nervous system. The contribution of H1- and H2-receptors to the effect of morphine on maximal electroconvulsive shock in mice was investigated in the present experiments. Morphine showed a dose-dependent anticonvulsive effect, but produced spontaneous clonic convulsions at higher doses (100 mg/kg, i.p.). The anticonvulsive effect of morphine (1 mg/kg, i.p.) was antagonized by histamine H1-receptor antagonists, dimethindene (0.1 mg/kg, i.p.) promethazine (0.4 mg/kg, i.p.) and pheniramine (30 mg/kg, i.p.), and naloxone (10 mg/kg, i.p.), but not by the H2-receptor antagonist ranitidine (10-50 micrograms, i.c.v.). These results show that morphine has an anticonvulsive effect via histamine H1-receptors against maximal electroconvulsive shock in mice.

Animals↗

Evaluation of the local anaesthetic activity of dimetindene maleate by means of laser algesimetry in healthy volunteers.

Dimetindene maleate (DMM, Fenistil, CAS 3614-69-5) a specific H1-receptor antagonist, is therapeutically used for the treatment of respiratory allergies, urticaria, itching dermatoses and generally pruritic sensations occurring with various diseases. As it exhibits local anaesthetic activity in the rabbit cornea and the local anaesthetic activity of a couple of H1-antagonists was found to be linearly correlated to the H1-potency represented by the pA2-values--and dimethindene maleate demonstrates a high pA2-value--it seemed worth investigating the local anaesthetic potency in man making use of an objective and well validated pain model, the Laser algesimetry. The study was carried out with 24 healthy volunteers in a double-blind placebo- and reference-controlled, randomized, cross-over design. Three different medications were applied with occlusive dressing: DMM, lidocaine, and placebo. Selective thermo-noxious stimulation of A-delta- and C-fibers was induced by a CO2-laser. Somato-sensory evoked vertex potentials (SEPs) were simultaneously recorded. Both verum treatments showed a remarkable analgesic potency compared to placebo. Effects were preferably concentrated on the peripheral N1-component of the SEPs. The overall means of the N1-amplitudes were suppressed compared to placebo by both active drugs, with the effects being more pronounced for DMM.

Adolescent↗