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At least 631 records · Page 35Linked to original sources

PubMed1986

Crystallographic and conformational studies on histamine H1-receptor antagonists. IV. On the stereochemical vector of antihistaminic activity.

The geometries of 14 histamine H1-receptor antagonists have been compared with the aim of finding out a common stereochemical vector of antihistaminic activity. The results obtained from X-ray crystallographic data have been compared with those obtained by minimizing the conformational energy of the molecules according to a simplified model of force field. Both approaches agree in indicating unique stereochemical requirements for optimum H1-antihistaminic activity.

Crystallography↗

PubMedDate not supplied

[Action of antihistaminic agents in patients with various heart pathologies undergoing surgical treatment].

Clinical observations and experimental studies enabled the authors to show that sensitivity of patients with rheumatic heart diseases to antihistaminic drugs is not always constant. It depends on pH value of the medium and blood concentration of calcium ions. It is advisable to include antihistaminic drugs in combination with colloid and crystalloid blood substitutes with regard to pH of the medium into the complex of agents for pre-, intra- and postoperative medication.

Adolescent↗

PubMed1986

[Treatment of urticaria with the new H1 antihistaminic astemizole--with special reference to the time of onset of effect and maximum effect].

20 patients, 12 suffering from chronic urticaria, 2 from acute urticaria, 1 from pressure urticaria, 2 from cold urticaria and 3 from urticaria factitia were treated in an open pilot study with the new H1-antihistamine Astemizole. The dosage was in all cases 1 X 10 mg per day. The onset of action as well as the efficacy maximum were registered. Astemizole proved in this study to be a very effective antihistamine being able to achieve good results even in hard to cure cases like cold urticaria. On the 1. day 35% of the patients had noticed an onset of action. 75% of the patients had an onset of action within the first 2 days. The efficacy maximum was achieved within the first 2 days in 60% of the patients.

Adolescent↗

PubMed1986

Enhancement of morphine-induced hyperactivity by antihistaminic drugs in mice.

Three histamine H1-receptor antagonists, chlorpheniramine, diphenhydramine and tripelennamine, were tested alone or in combination with morphine on locomotor activity in C57BL/6 mice. All three antihistaminics, at some dosage levels, slightly increased activity when given alone, but strongly enhanced morphine-induced hyperactivity. The results demonstrate that locomotor activity represents a useful test to evidence stimulatory effects of antihistaminic-opiate combinations.

Animals↗

PubMed1987

[Therapy of urticaria with H1 and H2 antihistaminics. Results of clinical and experimental studies].

The antipruritic effect of modern H1- and H2-receptor blockers in chronic urticaria, that had been clinically proved, was experimentally studied by means of the histamine weal test. The H2-antihistamine preparation ranidine alone did not clearly reduce weals or erythemas induced by histamine when compared with a placebo. As expected, both parameters were markedly reduced by the H1-antihistamine preparation terfenadine. After combined administration of both drugs, the effect of the H1-blocker proved to be significantly increased. We discuss the possible mode of action and the consequences for anti-allergic therapy.

Benzhydryl Compounds↗

PubMed1987

Effects of H1 antihistamines on canine nasal vascular and airway resistances.

The effects of three commonly used H1 antihistamines on the nasal vascular and airway resistances were studied in the dog. Promethazine hydrochloride decreased nasal vascular resistance but increased nasal airway resistance in a dose-dependent manner. Diphenylpyraline hydrochloride in low doses increased nasal vascular resistance without affecting much nasal airway resistance while in high doses decreased nasal vascular resistance but increased nasal airway resistance. Chlorpheniramine maleate in low doses increased nasal vascular resistance but decreased nasal airway resistance while in high doses decreased nasal vascular resistance without affecting much nasal airway resistance. It was concluded that different H1 antihistamines might exert vasoconstrictor or vasodilatatory action on both the resistance and capacitance vessels of the nasal vascular bed depending on the type and the dose of the drug used.

Airway Resistance↗

PubMed1987

Comparative two-phase clinicopharmacological trial of a new antihistaminic, EGYT-2062, setastine.

During the two-phase clinicopharmacological trial in humans of a new antihistaminic compound EGYT-2062, setastine developed by EGIS Pharmaceutical Company, Budapest, was tested the tolerance to the drug, its pharmacodynamic effect by i. c. histamine and acetylcholine tests, and its effect on the CNS by neuropsychiatric examination on eight healthy volunteers. The side-effects appearing during treatment were recorded. A self-controlled blind study was performed. The reference compound was clemastine. Based on the results, for prolonged use a dose of 2 mg three times/day (t.i.d.) is recommended. The antihistaminic effect of setastine almost equalled that of clemastine given in a dose of 1 mg t.i.d., while its antiacetylcholine effect exceeded it, and in view of its few psychic side-effects, might be tolerated better than clemastine.

Acetylcholine↗

PubMedDate not supplied

[Dependence of the absorption through the human oral mucosa of antihistaminic (H1) preparations on their physicochemical properties].

Antihistaminic (H1) drugs pipolphen, suprastin and dimedrol are characterized according to absorption through human oral mucosa and distribution between phosphate buffer solution and organic solvents at various medium pH values. Their constants of ionization and coefficients of distribution in the n-octanol--phosphate buffer system, pH 7.4, as well as the bound fraction at the interaction of these drugs with human serum albumin were determined. The relationship between absorption through human oral mucosa of antihistaminic drugs and the hydrophobic character of their molecules and constants of ionization was found. An attempt was made to predict for them on the basis of the authors' own results and literature data possible pharmacokinetic and pharmacodynamic behavior in the organism.

Absorption↗

PubMed1988

[A new H1-blocking antihistamine. Critical review of pharmacological and clinical studies].

Astemizole is a long-acting antihistamine that blocks the H1 receptors. Thanks to its long-acting effect, symptoms can be controlled by a single daily dose. Its efficacy in the treatment of seasonal and permanent allergic rhinitis has been demonstrated in many studies in which it was compared with other antihistamines. It has also proved useful in the treatment of allergic conjunctivitis and chronic urticaria. Though a tendency to increased appetite and slight weight gain after prolonged use has been noted in some patients, astemizole is not sedative and has no anticholinergic effect in the standard therapeutic doses.

Animals↗

PubMed1988

Antihistaminic and antimuscarinic effects of amitriptyline on guinea pig ileal electrolyte transport and muscle contractility in vitro.

Amitriptyline, a tricyclic antidepressant, was tested for antimuscarinic and antihistamine effects against bethanechol and histamine-stimulated contractility and secretion in the guinea pig ileum in vitro. Comparisons were made with muscarinic-receptor antagonists, as well as with H1 and H2 histamine-receptor antagonists. Amitriptyline (0.01-5.0 microM) produced a parallel rightward shift in the concentration-response curves to histamine in muscle (Ki 0.4 nM) and mucosa (Ki 450 nM). The H1-receptor antagonists pyrilamine and diphenhydramine were less potent against histamine in the muscle and more potent against histamine in the mucosa than was amitriptyline. The H2-receptor antagonist cimetidine was ineffective in the muscle and mucosa. Amitriptyline (0.1-2 microM) also produced a parallel rightward shift in the concentration-response curve to bethanechol in muscle (Ki 133 nM) and mucosa (Ki 143 nM). Against bethanechol, in both tissues, atropine and 4-diphenylacetoxy-N-methyl piperidine methiodide were more potent competitive antagonists than was amitriptyline. Pirenzepine produced a competitive blockade of bethanechol in the muscle and a noncompetitive blockade in the mucosa. The data indicate that amitriptyline exerts more potent antihistaminic effects on guinea pig ileal muscle than the mucosa but that the tricyclic drug is equipotent as an antimuscarinic in both tissues.

Amitriptyline↗

PubMed1988

[General review of a non-sedative antihistaminic, astemizole (Hismanal), a H1 receptor antagonist].

The non-sedating antihistamine Astemizole seems to approach all the major characteristics of the ideal histamine H1 antagonist, according to a comprehensive review of 54 clinical trials and clinical use in over 6,500,000 patients worldwide. The following statements concerning Astemizole can now be made: Astemizole is more potent than any other known antihistamine, following Astemizole therapy, H1 blockade is complete in the main target tissues, such as nasal and ocular mucosa, this blockade is also specific, since all histamine-mediated signs and symptoms respond to the drug, this blockade is maintained, since tolerance does not appear during long-term treatment. Astemizole is a non-sedative and non-toxic drug, even during chronic use. Astemizole is very effective in patients with chronic urticaria. Astemizole has well-documented beneficial protective effects on histamine-induced bronchoconstriction.

Astemizole↗

PubMed1988

Antihistamines and driving safety.

The results of two placebo-controlled driving performance studies confirm laboratory data showing that the nonsedating antihistamine terfenadine does not influence the driving performance of users. The amplitude of vehicle weaving calculated for drivers who received this agent did not differ from control values. Neither terfenadine nor loratadine, another nonsedating antihistamine, potentiated the adverse effects of alcohol on driving performance.

Automobile Driving↗

PubMed1988

Antihistamines in the treatment of urticarial disorders.

A number of studies of the effects of antihistamines on chronic idiopathic urticaria and itch are reviewed. In chronic idiopathic urticaria, terfenadine has been shown to control the number, size, and duration of skin whealing as well as itch. Likewise, in chronic dermatographic urticaria, the minimal force required to produce whealing is increased, while severity of itch is decreased following treatment with terfenadine. In both conditions, however, wheal formation is not completely inhibited, suggesting the involvement of a mechanism unrelated to histamine. In nonurticarial disease in which histamine is not involved in the pathogenesis, antihistamines appear to work as antipruritics, but by a sedative-related property and not by antagonism of H1-receptors.

Astemizole↗

PubMed1988

Pharmacology and toxicology of nonclassical antihistamines.

Within the past five years the introduction of a new class of antiallergy drug, the nonsedating antihistamine, has changed the way allergy sufferers are treated. The first example of this new therapeutic class, terfenadine, is a highly specific H1-receptor antagonist devoid of central nervous system activity. In clinical trials to date involving more than 7,000 allergy patients, terfenadine (60 mg twice daily) has been shown to be unsurpassed in efficacy, to have a rapid onset of action, and to have an incidence of sedation not different from that of placebo and considerably less than that of conventional antihistamines. In addition, results of task performance studies, including on-the-road driving studies, have demonstrated a lack of performance impairment with terfenadine at single oral doses of 60 to 240 mg, or with multiple oral doses of 60 mg twice daily for one week. Furthermore, no interaction has been observed between terfenadine and alcohol or diazepam. Postmarketing surveillance of more than 1 billion patient days has substantiated this remarkably safe and effective clinical profile.

Astemizole↗

PubMed1988

[Bibliographic review of antihistaminics H2 in the treatment of chronic (or recurrent) idiopathic urticaria].

Cimetidine alone has not been shown conclusively to be effective in the treatment of urticaria. Cimetidine in combination with an H1 antihistamine has been shown to be effective in studies of patients who could not be controlled by H1 antihistamine alone. In that section of the patient population with "untreatable" chronic urticaria, the use of an H2 antagonist in conjunction with an H1 antagonist should be considered as a possible treatment.

Histamine H1 Antagonists↗

PubMedDate not supplied

Antihistaminic-opioid combination: effect on locomotor activity in mice.

Various laboratory studies have been recently prompted by reports indicating abuse by heroin addicts of the narcotic agonist-antagonist pentazocine combined with the antihistaminic tripelennamine. For what concerns the effects on locomotor activity, it was demonstrated that three histamine H1 receptor antagonists, chlorpheniramine, diphenhydramine and tripelennamine enhance morphine-, but not amphetamine and scopolamine-induced hyperactivity in mice. These results suggested that antihistaminics may specifically interfere with locomotor effects of opioids. Such hypothesis was strengthened by further findings indicating enhancement by tripelennamine of the locomotor stimulation induced by buprenorphine, a drug possessing morphine-like properties.

Amphetamine↗

PubMed1979

Cardiorespiratory assessment of decongestant-antihistamine effects on altitude, +Gz, and fatigue tolerances.

Decongestants and antihistamines are known to produce effects capable of adversely modifying physiological function and psychomotor task performance. Because of relevance to safe pilot performance, the effects of single doses of two decongestant-antihistamine preparations (Compound A and Compound B), or a placebo on cardiorespiratory responses to two equally spaced +2 Gz tests during separate 2-h exposures at 388 m (1,274 ft MSL) ground level (GL) and 3,810 m (12,500 ft) chamber altitude were assessed. Post-altitude fatigue was assessed by cardiorespiratory responses to submaximal bicycle ergometry. Compound A and Compound B appeared to exert no significant detrimental effects on short-duration post-altitude ergometric fatigue-ability. With two exceptions, all combinations of medication, altitude, and +Gz were well tolerated. Two subjects were clearly incapacitated during the first +2 Gz test under Compound A at 3,810 m (12,500 ft) altitude. It is felt that the +Gz-intolerance resulted mainly from an adverse interactive effect of Compound A and altitude on vasomotor and/or chronotropic mechanisms.

Adult↗

PubMedDate not supplied

Polarographic determination of antihistamines by complexation with Cd(II).

the polarographic behavior of the complexes formed by Cd(II) ion with ethanolamine derivative antihistamines such as diphenhydramine hydrochloride, dimenhydrinate, and chlorphenoxamine hydrochloride was studied. Antihistamines form spontaneous complexes with Cd(II) ion in the presence of KNO3. In addition, pH 8.00 borate buffer was added to increase the differential pulse polarogram peak height, and tetraalkyl ammonium salts were added to increase the linear range. The method of determination developed has been applied to commercial tablet, capsule, elixir, and injection forms of ethanolamine derivative drugs and has been compared with official methods.

Cadmium↗