Dual effect of clonidine on isolated rabbit pulmonary arteries

The additive effect of clonidine to lidocaine on postoperative pain management after root canal treatment on mandibular molars with symptomatic irreversible pulpitis: A prospective randomised double-blind clinical trial

Context:

Postoperative pain control has been a common challenge to clinicians in endodontics.

Aims:

This double-blind randomized clinical trial assessed the efficacy of clonidine added to lidocaine for postoperative pain following endodontic treatment of mandibular molars with symptomatic irreversible pulpitis (SIP).

Methods:

One hundred participants with lower molars experiencing SIP were recruited and randomly assigned to two groups. 1.8 mL of 2% lidocaine with either epinephrine (1:80,000) or clonidine (15 µg/mL) was administered to each group via an inferior alveolar nerve block. A Heft–Parker Visual Analog Scale was used to rate preoperative pain and at 6, 12, 24, 36, 48, and 72 h following endodontic treatment. Their postoperative analgesic consumption was recorded.

Statistical Analysis Used:

The analgesic efficacy was analyzed by Chi-square test, paired t-test, and repeated measures ANOVA (P < 0.05).

Results:

Early postoperative pain was significantly lower in the lidocaine/clonidine group than the lidocaine/epinephrine group (6 h: P = 0.038; 12 h: P = 0.031). The lidocaine/clonidine group consumed a significantly lower amount of analgesics (P = 0.048).

Conclusions:

The administration of clonidine added to lidocaine may reduce early postoperative pain and consumption of analgesics following endodontic treatment in lower molars with SIP.

Anesthetic Success Using Nitrous Oxide and a Combination of Lidocaine/Clonidine for the Inferior Alveolar Nerve Block and the Effects on Blood Pressure and Pulse in Patients with Symptomatic Irreversible Pulpitis: A Prospective, Randomized, Double-blind Study

INTRODUCTION

The pulpal anesthetic success rates for an inferior alveolar nerve block (IANB) alone in patients presenting with symptomatic irreversible pulpitis are less than adequate. Nitrous oxide and clonidine have shown increases in IANB success when administered individually, but their success has not been evaluated when used together. The purpose of this prospective, randomized, double-blind study was to determine the effect of nitrous oxide/oxygen plus an IANB using lidocaine/clonidine on the success of the IANB in patients with symptomatic irreversible pulpitis and to evaluate the effect of clonidine on blood pressure and pulse.

METHODS

Sixty-two emergency patients experiencing moderate to severe pain and a diagnosis of symptomatic irreversible pulpitis were enrolled. Subjects were randomly divided into 2 groups and received nitrous oxide/oxygen and an IANB using 2% lidocaine with either 27 μg clonidine or 18 μg epinephrine as vasoconstrictors. Blood pressure and pulse were recorded before and during the emergency endodontic treatment. Anesthetic success was defined as no or mild pain upon access and instrumentation of the canals.

RESULTS

The pulpal anesthetic success rate in both treatments was 58%, with no significant difference between the groups. There was no statistically significant difference in pulse or systolic blood pressure with the use of clonidine compared with epinephrine. Diastolic blood pressure was significant.

CONCLUSIONS

The use of nitrous/oxide plus the addition of lidocaine/clonidine for the IANB in teeth with symptomatic irreversible pulpitis resulted in no statistically significant difference in anesthetic success of the IANB. There were no statistically significant differences in pulse or systolic blood pressure with the use of clonidine compared with epinephrine; diastolic blood pressure was significant.

Lidocaine+clonidine for maxillary infiltration anaesthesia: parameters of anaesthesia and vascular effects

The local anaesthetic and haemodynamic parameters achieved by lidocaine with clonidine or epinephrine, administered for maxillary infiltration anaesthesia, were studied in 40 patients (American Society of Anesthesiologists, physical status 1) who underwent upper third molar surgery. All patients received 2 ml of 2% lidocaine with clonidine (15 microg/ml; n=20) or epinephrine (12.5 microg/ml; n=20) in a randomized, double-blind fashion. Vascular effects were evaluated on the isolated human infraorbital arteries. The parameters of maxillary infiltration anaesthsia produced by a combination of lidocaine+clonidine were similar to those obtained with lidocaine+epinephrine. In both groups, haemodynamic parameters exhibited similar variations, with the exception of a significant reduction in heart rate and systolic blood pressure in the lidocaine+clonidine group and significant increase in heart rate in the lidocaine+epinephrine group, 10 min after surgery. Clonidine (10(-7), 10(-6) and 10(-5)M) produced an endothelium-independent vasocontractile effect on the isolated human infraorbital arteries. The results of this study indicate for the first time in dental anaesthesia that the lidocaine+clonidine combination could be a useful and safe alternative to lidocaine+epinephrine for intraoral infiltration anaesthesia.

Comparative vasoactive effects of amrinone on systemic and pulmonary arteries in rabbits

Amrinone has been increasingly used in management of low cardiac output syndrome during anesthesia, particularly when associated with right heart failure and pulmonary hypertension. This in vitro study was performed to determine and compare the direct vasoactive effects of amrinone on isolated rabbit systemic and pulmonary arteries. Responses of aortic and pulmonary artery rings from New Zealand white rabbits were assessed in the presence and absence of intact endothelium and with or without precontraction by norepinephrine (NE, 3 x 10(-6)M) or potassium chloride (KCl, 3 x 10(-2)M). Using a tissue bath preparation, cumulative concentration response curves of amrinone were obtained at different concentrations after a period of stabilization. Amrinone caused a dose-related vasodilation of NE-precontracted aortic and pulmonary arteries. It elicited about 65% and 90% relaxation, respectively, at a concentration of 300 mumol/L. Amrinone also induced a dose-related vasodilation of KCl-precontracted aortic and pulmonary arteries but to a lesser degree. All these effects were endothelium independent. By comparison, amrinone caused more relaxation in both NE- and KCl-precontracted pulmonary artery than aortic rings. In conclusion, amrinone has significant endothelium-independent, direct vasodilatory effects on isolated rabbit systemic and pulmonary arteries, more pronounced in the latter, particularly NE-precontracted vessels. Amrinone may have some calcium channel-blocking effect.