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Results for “Histamine Antagonists”

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At least 19 recordsLinked to original sources
PubMedDate not supplied

Perioperative uses of histamine antagonists.

Histamine release and adverse pseudoallergic/allergic reactions during the perioperative period occur frequently. The incidence of such reactions is 20%-30% for all grades of severity, 1%-5% for systemic reactions, and 0.1%-0.5% for life-threatening reactions. They can be elicited by all commonly used anesthetic agents and by surgical interventions. Both the incidence and severity can be reduced by the use of combined prophylaxis with H1- + H2-receptor antagonists. The authors recommend that this prophylaxis be given to the following groups of patients: those with a history of adverse reactions or history of allergy, patients undergoing surgery with a high risk of histamine release, elderly patients, and those with poor physical status due to underlying systemic diseases. These indications have been developed by heuristic medical decision-making, including a decision tree.

Histamine H1 Antagonists↗
PubMed2003

[H1 histamine antagonists].

Histamine is an important mediator for early phase allergic reactions that are involved in atopic diseases, mediated by specific IgE antibodies. After allergenic contact, its liberation induces unpleasant symptoms like itching, several manifestations as local vasodilatation, bronchoconstriction, mucus hypersecretion. Antagonists of H1 histamine receptors are the most prescribed drugs, due to their symptomatic effects at the levels of nasal or conjunctival mucosa, and the skin. Their major indications cover allergic rhinitis, either seasonal or perennial, and idiopathic chronic urticaria, as a first line medication. The pharmacological evolution allows to distinguish three generations of products differing at the levels of specificity, long acting period, and toxicity. The authors are discussing the respective benefits of two recent molecules presented as 3rd generation molecules: fexofenadine and levocetirizine, while repositioning their use among available treatment strategy.

Acetates↗
PubMed1990

Dose-response relationship of the H1-histamine antagonist, ebastine, against histamine and methacholine-induced bronchoconstriction in patients with asthma.

In a double blind, randomised, placebo controlled trial in a group of extrinsic asthmatics, we have evaluated the potency and selectivity of ebastine, a new piperidine-type H1-receptor antagonist, against histamine and methacholine-induced bronchoconstriction. The median histamine PC20FEV1 value following placebo was 3.15 mg/ml (0.24-58.84). When compared with placebo, ebastine produced significant protection at 10 mg (median PC20 = 31.36 mg/ml, p = 0.008) and 30 mg (median PC20 = 42.14 mg/ml, p = 0.001) but there appeared to be no significant dose effect. Ebastine also produced a small shift in the methacholine concentration-response curves to the right. We conclude that ebastine is an effective antagonist of histamine-induced bronchoconstriction in the asthmatic airway with evidence of minor blockade of methacholine-induced bronchoconstriction.

Adult↗
PubMedDate not supplied

Opiate mixed agonist-antagonist interactions with histamine antagonists vs. morphine.

Anecdotal reports of polydrug abuse in humans using tripelennamine and pentazocine prompted our investigation of drug interactions between tripelennamine, morphine and various synthetic mixed agonist-antagonists in mice. Pentazocine, nalbuphene and butorphanol, at doses of 4.0-8.0 mg/kg, all showed frank or borderline intrinsic antinociceptive activity and potentiated the tripelennamine response, whereas cyclazocine, an experimental compound with very strong mixed agonist-antagonist qualities at 5.0 mg/kg, showed intrinsic antinociceptive activity but was not potentiated by tripelennamine and actually blocked the tripelennamine response. In a comparative study, pentazocine, butorphanol and nalbuphene had no effect on morphine antinociception whereas cyclazocine completely abolished the antinociceptive effects of morphine. Cimetidine blocked the response of cyclazocine, but not nalbuphene, pentazocine or butorphanol. Our findings demonstrate that the mechanism of action of cyclazocine is significantly different from that of the other mixed agonist-antagonists studied. They also suggest possible histaminergic involvement in antinociception, as well as a locus for antinociception separate from the opiate receptor.

Analgesics↗
PubMed1986

The effects of combined H1 and H2 histamine antagonists on alterations in nasal airflow resistance induced by topical histamine provocation.

A clinical trial was undertaken to assess the effects of oral H1 (diphenhydramine hydrochloride) and H2 (cimetidine) histamine blockade on nasal resistance induced by topical histamine. Ten adult volunteers were tested on two separate occasions. Their noses were pretreated by oral administration of either combined H1 and H2 histamine antagonists or H1 antagonist and placebo. The nasal airflow resistive response to topical histamine was then determined. Combined histamine antagonism was significantly more effective in reducing the nasal resistive response to topical histamine than H1 antagonist alone (p less than 0.0001). Furthermore, ingestion of the oral H1 histamine antagonist, diphenhydramine hydrochloride, alone led to an increase in resistance of the unprovoked nose, whereas combined H1 and H2 antagonism did not lead to a significant change.

Adult↗
PubMedDate not supplied

[Role of histamine as an intermediary in the action of estradiol on the rat uterus: inhibition of the hormonal induction of enzymes using histamine antagonists].

The administration of methiamide, a blocker of histamine H2-receptors, to rats was shown to prevent the induction of hexokinase (HK) and glucose-6-phosphate dehydrogenase (G-6PD) caused by both histamine and estradiol. An inhibitory effect of methiamide remained stable up to 16 h after histamine and estradiol administration. Diphenhydramine, a blocker of histamine H1-receptors, produces a short-term inhibitory effect on the HK and G-6PD activity stimulated by histamine and estradiol. The short-term nature of the diphenhydramine effect may be attributed to a low affinity to histamine H2-receptors and histamine fast dissociation. It may be concluded that some of the estradiol effects, particularly the HK and G-6PD induction in the uterus are histamine-mediated, apparently by means of H2-receptors. The administration of histamine to rats increases the uterus mass causing its inundation, and H1- and H2-blockers prevent this effect of histamine. However, the above histamine antagonists do not inhibit uterus inundation caused by estradiol. A conclusion is made that estradiol stimulates the uterus inundation not only by means of histamine but also by some other means.

Animals↗
PubMed1981

The use of H1 and H2 histamine antagonists with morphine anesthesia: a double-blind study.

High doses of morphine can produce significant cardiovascular effects generally attributed to histamine release. The authors examined the possibility that H1 and H2 histamine antagonists might prove beneficial in preventing these responses. In a randomized double-blind study, four groups of 10 patients each received 1 mg/kg morphine and either a placebo, diphenhydramine (H1), cimetidine (H2), or both of the histamine antagonists. The morphine-placebo group demonstrated a marked elevation in plasma histamine levels (880 +/- 163 to 7437 +/- 2684 pg/ml), a decrease in systemic vascular resistance (SVR) (15.5 to 9.0 l torr/(l . min-1) and diastolic BP (71 +/- 3 to 45 +/- 4 torr) and an increase in cardiac index (CI) (2.4 +/- 0.2 to 3.0 +/- 0.21 . min-1 . m-2). The administration of either cimetidine or diphenhydramine with morphine provided minimal protection. Those patients who received morphine and both antagonists demonstrated significant attenuation of these responses (CI 2.5 +/- 0.2 to 2.5 +/- 0.1 l . min-1 . m-2; SVR 17.4 to 14.6 torr/(l . min-1) although plasma histamine levels showed a comparable increase (1059 +/- 222 to 7653 +/- 4242 pg/ml). These data demonstrate directly that many of the hemodynamic effects of morphine can be attributed to histamine release. They further demonstrate that significant hemodynamic protection can be obtained by the use of histamine antagonists and the combination of H1 and H2 antagonists is superior to either given alone.

Blood Pressure↗
PubMed1996

Circadian rhythm photic phase shifts are not altered by histamine receptor antagonists.

Histamine may play a role in synchronizing endogenous circadian rhythms with exogenous photic cues. Direct application of histamine to the suprachiasmatic nucleus, the site of the mammalian circadian pacemaker, phase shifts the circadian rhythm in neural activity [7]. Intraventricular injections of histamine also phase shift circadian rhythms [14]. The magnitude and direction of the phase shifting effects of histamine depend on circadian phase in a manner similar to light [7,14]. Depletion of brain histamine levels by inhibition of histamine synthesis reduces phase shifts to light [10].

Animals↗
PubMed1999

Exploratory behaviour after intra-accumbens histamine and/or histamine antagonists injection in the rat.

The possible role of histamine locally applied into the nucleus accumbens on exploratory behaviours measured in 'conflictive' and 'non-conflictive' environments was studied in adult male rats. It was assumed that in conflictive environments the brain mechanisms involved in processing incentive environmental clues (novelty) were interacting with mechanisms involved in the processing of fearful or 'anxiogenic' environmental clues. As a model of conflictive environment, the elevated asymmetric-plus maze (APM) was used. As a model of a non-conflictive environment, a modified holebroad enriched with an object (OVM) was used. The exploration score in any of the arms of the APM was considered an approximate index of exploratory motivation. The permanency score (non-exploratory behaviours) was considered an inverse approximate index of emotionality. Other variables such as the frequency of entries into any arm, the latency time and central activity were also measured. In the OVM, the general motor activity and head-dipping, vertical rearing and focalized exploration were measured. Results show that histamine in the APM had a dual effect. On the one hand, an increase of exploration was observed in those arms considered more 'anxiogenic'. On the other hand, a decrease in exploration occurred in one of the arms considered less 'anxiogenic'. No changes of permanency was observed in the 'anxiogenic' arms, and a decrease of permanency took place in the arms considered less 'anxiogenic'. In the OVM, histamine did not change the overall motor activity, but head-dipping was inhibited by the imidazolamine treatment. Histamine effects on exploration parameters were counteracted by pre-treatment with H1- and H2-histamine antagonists. Nevertheless, some behaviours were not blocked by the histamine receptor antagonists. The present results give support to the role of the nucleus accumbens in the exploratory motivation mechanisms and suggest that histamine might be an endogenous regulator.

Animals↗
PubMed2000

A third life for burimamide. Discovery and characterization of a novel class of non-opioid analgesics derived from histamine antagonists.

Burimamide, a histamine (HA) derivative with both H2- and H3-blocking properties, induces antinociception when injected into the rodent CNS. Several related compounds share this property, and structure-activity studies have shown that this new class of analgesics is distinct from known HA antagonists. The prototype, named improgan, shows a preclinical profile of a highly effective analgesic, with activity against thermal, mechanical and inflammatory nociception after doses that do not alter motor balance or locomotor activity. Improgen analgesia is not blocked by opioid antagonists and is observed in opioid receptor knock-out mice. Unlike morphine, improgan does not induce tolerance after daily dosing. Extensive in vitro pharmacology studies have excluded known histaminergic, opioid, serotonergic, GABAergic and adrenergic receptor mechanisms, as well as 50 other sites of action. The improgan-like analgesic activity of some HA congeners suggests an analgesic action on a novel HA receptor, but further studies are required to substantiate this. Studies in progress are characterizing the sites and mechanisms of action of improgan, and developing brain-penetrating derivatives that could be useful for clinical pain.

Analgesics, Non-Narcotic↗