Intradermal histamine release by 3 muscle relaxants

Neuromuscular transmission and its pharmacological blockade. Part 4: Use of relaxants in paediatric and elderly patients, in obstetrics, and in the intensive care unit

The pharmacodynamic and pharmacokinetic characteristics of the non-depolarizing muscle relaxants are dependent on age. Thus differences are found between paediatric patients, adults, and elderly patients. Muscle relaxants cross the placenta and thus may cause problems in the fetus. Many of the potential adverse effects of relaxant administration are seen more pronounced in intensive care patients. Prolonged effects and problems in wearing patients from the ventilator are observed when muscle relaxants are used in such patients. Critical illness neuropathy is a syndrome different from relaxant induced neuromyopathy, but may be enhanced by relaxant administration.

HISTAMINE RELEASE AND CHANDONIUM IODIDE

Histamine releasing activity of chandonium iodide and d-tubocurarine was studied in guinea pig ileum (in vitro), guinea pig peritoneum (in vivo) and in human volunteers (in vivo) by intradermal testing at dilutions of 1:1,000 and 1:10,000 of the clinical dosage of drugs. d-tubocurarine revealed significant histamine releasing activity in in vivo animal experiments and high incidence of positive intradermal reaction, 53.5 per cent and 13.5 per cent, in human volunteers. Chandonium iodide neither showed histamine releasing activity in animals nor in man. In clinical terms, chandonium iodide appears to be a safe neuromuscular blocking agent.

Wheal and flare responses to muscle relaxants in humans

Chemically and pharmacologically unrelated molecules release histamine in humans to produce both cutaneous and systemic responses. It has been suggested that molecular changes in the new benzylisoquinoline-derived muscle relaxant, atracurium, make it less likely to cause histamine release. We therefore injected volunteers intradermally with equimolar concentrations of various muscle relaxants, morphine, papaverine (a benzylisoquinoline), and histamine, to evaluate the relative ability of these drugs to cause wheal and flare responses, and mast-cell degranulation. There were no significant differences in wheal and flare responses among the three benzylisoquinoline-derived muscle relaxants, D-tubocurarine, metocurine, and atracurium. The cutaneous effects of morphine were significantly greater than those of the benzylisoquinoline muscle relaxants, suggesting both direct vascular changes and histamine release. Papaverine injection was followed by a significant wheal but no flare. Skin biopsies from vecuronium- and papaverine-induced wheals revealed normal intact mast-cell granules, suggesting a direct cutaneous vascular response rather than histamine release. Skin biopsies after morphine and atracurium injections revealed mast-cell degranulation. All evaluated benzylisoquinoline muscle relaxants are equipotent histamine releasers at equimolar concentrations. A hydrogenated, benzylisoquinoline-nitrogen-containing ring, present in atracurium but not in papaverine, appears to be the molecular conformation responsible for mast-cell degranulation by atracurium.

Changes in the plasma histamine concentration after the administration of vecuronium bromide

Clinical symptoms of anaphylactoid reaction to muscle relaxants vary from localized flush to cardiovascular collapse. Vecuronium bromide is reported to have very little histamine releasing property. However, there are some reports of anaphylaxis or anaphylactoid reaction to vecuronium. We studied plasma histamine concentration after the intravenous injection of vecuronium to confirm the histamine release. Twenty patients were randomly allocated to one of two groups, each group comprising of 10 patients: one group was to receive vecuronium 0.1 mg.kg(-1) and the other 0.2 mg.kg(-1) using the priming principle. Blood samples were taken prior to and 1, 3, 5, 8 and 13 min after the administration of vecuronium. The plasma histamine concentration was measured by radioimmunoassay with monoclonal antibody. There were no significant changes in plasma histamine concentration over 13 min after the administration of vecuronium compared with the baseline value. There were also no significant differences between these two groups. We concluded that vecuronium up to 0.2 mg.kg(-1) did not change the plasma histamine concentration in the patients having no previous history of allergy or atopic tendencies.

Effects of pancuronium and vecuronium on creatine phosphokinase in rat isolated heart, liver, kidney and diaphragm

1. The effects of two muscle relaxants, namely, pancuronium and vecuronium, on creatine phosphokinase (CPK) release from four different types of tissues, namely, heart, liver, kidney and diaphragm, were studied in the rat in vitro. 2. The total, neat and CPK levels (units/ml), released by muscle relaxants were measured using spectrophotometric determination at 340 nm. 3. The results showed that both muscle relaxants, in low concentrations, i.e. 0.34 or 0.32 microM, close to a clinical dose of 0.1 mg/kg, had no significant effect on CPK leakage in all four types of tissues studied. However, in concentrations 12-122 times clinical dose, the two muscle relaxants produced differential adverse effects in the tissues studied. 4. In most concentrations, pancuronium and vecuronium produced significant increases in the CPK release in the kidney and diaphragm. In contrast, pancuronium had no significant effect on CPK release in the liver and the lowest effect in the heart. Similar results were obtained with vecuronium. 5. The clinical relevance and/or implications of the present results are discussed and the results are compared to those previously reported by other workers in other preparations.

No cutaneous histamine release with buprenorphine?

Most narcotics cause histamine release, both systemic and cutaneous. Whether buprenorphine causes histamine release is not yet known. We conducted intradermal tests on 11 healthy adults with buprenorphine in dilutions of 1:10,000, 1:1000, 1:100 and 1:10 and with 0.9% saline and histamine 10(-3) mol/l. The size of dermal reaction was noted after 15 and 30 min. None of the volunteers showed any cutaneous reaction suggestive of histamine release with buprenorphine. The absence of histamine-releasing activity of buprenorphine may be due to the structure of the drug resulting in its decreased basicity or to the insufficient concentration of the drug achieved at mast cell membrane.

A pharmacologic study on the histamine releasing effect of atracurium and other muscle relaxants in rat isolated ileum

In this study, the effects of histamine, antihistamines (terfenadine and mepyramine), 5-hydroxytryptamine, and muscle relaxants, atracurium, vecuronium and gallamine, on the tone and contractility of rat ileum were studied and compared in vitro. The aim of the present investigation was to measure, pharmacologically, the histamine releasing effect of muscle relaxants, e.g atracurium, vecuronium and gallamine, by comparing their contractile response in the absence and presence of antihistamines and comparing their mechanical responses with those produced by histamine and 5-hydroxytryptamine (5-HT). The results showed that the antihistamines, triludan(terfenadine) and mepyramine produced opposite effects in rat ileum. Terfenadine (0.1-20 microM) produced concentration-dependent contractions in the rat ileum, whereas mepyramine (0.1-10 microM) relaxed the muscle, e.g. by 1.2 g tension. Atracurium (0.5-500 microM), vecuronium (0.2-200 microM), and gallamine (0.1-7.0 microM) produced marked contractions (1.5-4.0 g tension) in rat ileum, and these contractions were markedly reduced by mepyramine (1.3 microM) or terfenadine (5 microM), implicating histamine release in the generation of these contractions. However, there was some residual contraction which was not blocked by mepyramine, but by 5-HT antagonist, methysergide (1 microM), indicating that a mechanism other than histamine release may be responsible for the residual contraction, i.e. release of other mediators such as 5-HT, prostaglandins, or calcium. 5-HT (0.5-500 microM) and histamine (0.5-500 microM) produced contractions in the rat ileum, but 5-HT was more effective than histamine in producing these contractions. Similarly, gall amine was more effective than atracurium and vecuronium in contracting the rat ileum.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative cutaneous histamine release by neuromuscular blocking agents

Normal values of cutaneous wheal diameter following intradermal injection of six neuromuscular blocking drugs were determined. The relative cutaneous histamine-releasing ability of each drug was derived from calculated dose-response relationships. Equipotent neuromuscular blocking doses were found to have a cutaneous histamine releasing ability relative to pancuronium (= 1) of vecuronium 1.1: suxamethonium 1.7; alcuronium 5; atracurium 52; d-tubocurarine 172. A significant (P less than 0.001) variation was found between the dose-response slopes perhaps suggesting a variation in the mechanism of histamine release.

Plasma histamine levels following atracurium

Plasma histamine levels were determined in 41 patients, 1.5 and 4 minutes after the intravenous administration of 0.6 mg/kg of atracurium. Clinical features of histamine release were sought at the time of blood sampling. Sixteen patients had elevation of plasma histamine 2.6 (SD 1.2) ng/ml 1.5 minutes after the injection of atracurium. Plasma histamine had returned to control levels at 4 minutes. There was a poor correlation between plasma histamine levels and the clinical manifestations observed. We conclude that atracurium has a low plasma histamine release potential and that cutaneous reactions after atracurium do not always indicate that plasma histamine levels are elevated.

Atracurium in clinical anaesthesia: effect of dosage on onset, duration and conditions for tracheal intubation

Conditions for tracheal intubation at 90 seconds, time to onset of maximum block and duration of clinical relaxation after five different doses of atracurium, which ranged from 0.4 to 1.0 mg/kg were studied in 200 adult patients who were anaesthetized with nitrous oxide, oxygen and halothane or fentanyl. The conditions for intubation improved significantly with increasing doses, and were acceptable in 55% patients with a 0.4 mg/kg dose and in about 90% of those who received the two higher doses. The time to onset of complete block was 257 seconds with 0.4 mg/kg and decreased progressively to 124 seconds with 1.0 mg/kg. The duration of clinical relaxation under fentanyl anaesthesia averaged 29 minutes with 0.4 mg/kg and increased in a dose-related manner to 57 minutes with 1.0 mg/kg: halothane anaesthesia produced only a marginal increase. There was no evidence of cumulation with up to six repeat doses of 0.125 mg/kg. The only side effect noticed was cutaneous flushing observed in 42% of patients. This was again dose dependent, being 18% with 0.4 mg/kg and increasing to 73% after 1.0 mg/kg. There was associated hypotension and bronchospasm in one patient.

[Hemodynamic effects of atracurium in man]

Haemodynamic effects of atracurium at three doses (0.2, 0.6 and 1.2 mg . kg-1) were studied in thirty patients, anaesthetized with thiopentone (5 mg . kg-1) and fentanyl (0.2 microgram . kg-1 . min-1). No cardiovascular side-effects were observed with doses of 0.2 and 0.6 mg . kg-1. However, a 1.2 mg . kg-1 dose induced a transient but significant decrease in mean arterial pressure (-10%; p less than 0.001), maximal in the second minute, associated with an increase in heart rate (+10%; p less than 0.001) and cardiac index (+9%), and a decrease in systemic vascular resistance (-16%; p less than 0.001). The decrease in arterial pressure was constant in every patient and associated with a generalized flush in one of them. Histamine-release induced by atracurium may be one of the possible mechanisms involved in this hypotension.

Histaminoid responses to atracurium, vecuronium and tubocurarine

Sixty patients scheduled for elective surgery underwent intradermal testing with 0.1 ml of the following solutions diluted in 0.9% saline: vecuronium and tubocurarine (1 in 1,000), atracurium (1 in 1,000 and 1 in 10,000), thiopentone (1 in 100) and also a 0.9% saline control. Thirty minutes later, an area of erythema of greater than 1.5 cm, or a wheal exceeding 1.0 cm in diameter, was recorded as a positive reaction. The patients then randomly received equipotent doses of atracurium, vecuronium or tubocurarine during a standardized anaesthetic induction. Any cutaneous reaction and the percentage fall in systolic pressure three minutes after administration of the relaxant were recorded. In 51 patients plasma IgE levels were measured. The incidence of positive cutaneous reactions to intradermal and intravenous relaxants was significantly different with each agent (p less than 0.01). The percentage fall in systolic pressure after tubocurarine was significantly different relative to the other two agents (p less than 0.01). This was regarded as reflecting potency in releasing histamine and placed the relaxants in the same order: tubocurarine, atracurium and vecuronium. The response to intradermal administration was no guide to the subsequent response after intravenous administration of the three relaxants. IgE levels below 15 IU X ml-1 occurred significantly more often in females and were associated with a significantly higher incidence of cutaneous reactions after intradermal atracurium (1 in 1,000 and 1 in 10,000) (p less than 0.05 and 0.001 respectively) and tubocurarine (1 in 1,000). With these two agents, generalized flushing after intravenous administration was also more common in this group, relative to the normal/high IgE group.

Atracurium and vecuronium: two unique neuromuscular blocking agents

Atracurium and vecuronium are two new nondepolarizing skeletal muscle relaxants that were developed to overcome the deficiencies seen with currently available agents (tubocurarine, metocurine, pancuronium, and gallamine). Both compounds have unique metabolic profiles, separating them from other nondepolarizing agents. Neither drug depends on normal renal function for excretion and each can safely be given to patients with renal failure. Atracurium also does not depend on hepatic function for metabolism; however, vecuronium may require dosing adjustments in hepatic disease. Atracurium and vecuronium have similar onset times for muscle relaxation but shorter durations of action than other nondepolarizing muscle relaxants. Both agents produce minimal cumulative effects with repeated doses. A major advantage of both agents is their relative lack of cardiovascular effects when given in clinically effective doses, differing from other nondepolarizing muscle relaxants. Both agents produce a lower degree of histamine release than other agents, although atracurium appears to produce a higher incidence of histamine-like reactions than vecuronium. Vecuronium appears to be the agent of choice in patients with a history of asthma or allergy. The place in therapy for these new agents is discussed.