Potentiation of local lignocaine-induced sensory block by calcium channel blockers in rats

The impact of cardiovascular drugs on the efficacy of local anesthesia in dentistry

BACKGROUND AND AIM

Drugs used chronically by patients with diseases of the cardiovascular system (group C of the ATC classification) may act on adrenergic receptors and/or certain ion channels, which gives them the potential to interact with the action of local dental anesthetics. The aim of the study was to investigate the effect of systemically administered chronic cardiovascular medication (oral route) on the efficacy of intraoral local anesthesia in patients with diseases of the cardiovascular system.

PATIENTS AND METHODS

This was a prospective cohort study which analyzed the efficacy of local terminal anesthesia (onset of anesthesia, duration anesthetized area) in the upper jaw of 70 patients: 40 patients on medication for cardiovascular system disorders and 30 patients who were not using these drugs (the control group). The following cardiovascular drugs were used: beta blockers, angiotensin converting enzyme inhibitors, calcium channel blockers, vasodilatators, diuretics, angiotensin receptor blockers, antiarrhythmics, statins and alfa blockers.

RESULTS

The onset of anesthesia on the vestibular side was faster in those taking cardiovascular drugs (40.50±19.87 s) than the control patients (58.93±31.07 s; P = 0.004) and duration of anesthesia on this side was shorter. Although the difference was not significant, it was evident that on vestibular and palatal side the anesthetized area was more rapidly reduced in the patients taking cardiovascular drugs. The duration of cardiovascular therapy also had a significant impact on the anesthetized area.

CONCLUSION

Drugs acting on cardiovascular system may influence the effect of local anesthetics used in dentistry, possibly through interaction with autonomic receptors and ion channels.

Effect of Nicardipine on Haemodynamic and Bispectral Index Changes following Endotracheal Intubation

We investigated the effect of IV nicardipine on haemodynamic and bispectral index responses to the induction of general anaesthesia and intubation. Forty patients were randomly allocated to two groups of 20 to receive normal saline or nicardipine 15 μg/kg IV 30 s after induction. Ninety seconds later, tracheal intubation was performed. Systolic blood pressure, heart rate and bispectral index were measured at baseline, 1 min after induction, pre-intubation, and every minute until 5 min after endotracheal intubation. Rate–pressure product values were calculated. In the nicardipine group, systolic blood pressure decreased compared with the control group, and heart rate increased compared with the control group. Bispectral index and rate–pressure product showed no differences between the two groups. In conclusion, the administration of 15 μg/kg nicardipine IV does not affect anaesthetic depth in response to the induction of general anaesthesia and intubation.

Efficacy of diltiazem as an adjunct to lignocaine in intravenous regional anesthesia

Background:

Various adjuncts have been used with lignocaine to decrease tourniquet pain and prolong post-operative analgesia during intravenous regional anesthesia (IVRA). Calcium-channel blockers potentiate the analgesic effect of local anesthetics. This study was designed to evaluate the efficacy of diltiazem as an adjunct to lignocaine in IVRA with respect to tourniquet tolerance, perioperative analgesia, and quality of anesthesia.

Methods:

In this prospective, randomized, and double-blind study, 40 patients (American Society for Anesthesiologists grade I/II) undergoing elective hand surgery under IVRA were assigned into two groups of 20 each and administered IVRA either with lignocaine 3 mg/kg (group Lignocaine (L)) or lignocaine 3 mg/kg plus diltiazem 0.2 mg/kg (group Lignocaine-Diltiazem (LD)) with normal saline (total volume-40 ml). Hemodynamic parameters, onset of the complete sensory blockade, motor blockade, and intraoperative (tourniquet pain) and post-operative Visual Analogue Scale scores, total intraoperative and consumption of post-operative fentanyl intraoperative were recorded.

Results:

Sensory block was established in 2.5±0.688 min in group LD verses 5.60±0.851 min in group L. Motor blockade was established in 8.65±0.933 min in group LD and 13.46±0.604 min in group L. The mean VAS scores >3 were attained early at 30 min (3.1±0.912) in group L. Patients in group L requested early rescue analgesic at 30±8.633 min compared with 49.64±7.958 min in group LD.

Conclusions:

Diltiazem as an adjunct to lignocaine provided enhanced intraoperative and post-operative analgesia without any significant side effects.

Competitive and open channel block of recombinant nAChR channels by different antibiotics

Various antibiotics may impair neuromuscular transmission, provoking symptoms of myasthenia in patients with a compromised safety margin of the synaptic transmission, but little is known about the underlying mechanisms at the molecular level. Using a modified patch-clamp technique in combination with an ultrafast system for solution exchange we investigated the functional interaction of gentamicin, penicillin G, tetracycline, erythromycin and ceftriaxone with nAChR transiently transfected into HEK293 cells as a potential molecular target. Gentamicin, penicillin G, tetracycline and erythromycin induced a combination of open channel and competitive block of nAChR channel currents whereas ceftriaxone had no effect. The IC50 for the competitive block was close to or within the range of clinically relevant concentrations. Except for erythromycin the open channel block was observed only at higher concentrations. From our in-vitro results we conclude that competitive inhibition of nAChR channels by antibiotics is an important mechanism underlying the impairment of neuromuscular transmission under clinical conditions.

Effects of nicardipine and diltiazem on the bispectral index and 95% spectral edge frequency

BACKGROUND AND OBJECTIVE

Previous studies have shown that L-type voltage-sensitive Ca2+ channel blocking agents increased and the L-type Ca2+ channel activator Bay K 8644 reduced the general anaesthetic potency in animals. As the bispectral index correlates with the depth of sedation, we examined whether L-type Ca2+ channel blocking agents affect the bispectral index.

METHODS

Thirty hypertensive patients (systolic arterial pressure >160 mmHg) presenting for total intravenous anaesthesia with propofol, fentanyl and ketamine were recruited. Bispectral index monitoring was commenced directly the patients arrived in the operating theatre. All patients were given either nicardipine or diltiazem intravenously at the discretion of the anaesthesiologist in charge.

RESULTS

Twenty-three and seven patients received nicardipine or diltiazem, respectively. The bispectral index level (mean (95% confidence interval)) did not change with either drug. In the nicardipine group, the bispectral index at 0, 5, 10 and 15 min was 55 (52-58), 55 (51-59), 55 (52-59) and 56 (53-59), respectively. In the diltiazem group, values were 59 (48-71), 60 (51-70), 61 (52-71) and 61 (50-72), respectively. Both L-type Ca2+ channel blocking agents significantly decreased arterial pressure.

CONCLUSIONS

Clinical doses of nicardipine and diltiazem do not alter the bispectral index during general anaesthesia.

Effect of diltiazem and methylene blue on human sperm motility, viability and cervical mucus penetration: potential use as vas irrigants at the time of vasectomy

The purpose of this study was to identify compounds that could potentially be useful for vas irrigation at the time of vasectomy. We studied the in vitro effects of a group of membrane-active and ion-channel blocking agents on human sperm motility, viability and cervical mucus penetration. Diltiazem, an anti-arrhythmic drug, and methylene blue, an agent commonly used in vasography, showed the most promising effects with marked reduction of sperm motility and cervical mucus penetration after incubation with sperm for a short period of 15 min. Diltiazem was more effective than methylene blue in inhibiting the motility and viability of sperm. Furthermore, unlike methylene blue, diltiazem significantly compromised sperm viability. Other compounds studied, such as lidocaine, nicardipine and Neosporin((R)), showed only partial inhibitory activity. Based on the data reported herein, both diltiazem and methylene blue appear to be suitable candidates to be developed for vas irrigation at the time of vasectomy.

Effects of a calcium channel blocker on electrical activity in myofascial trigger spots of rabbits

OBJECTIVE

This study investigated the effect of a calcium channel blocking agent, verapamil, on the spontaneous electrical activity (SEA) in a myofascial trigger spot of biceps femoris muscles of rabbits.

DESIGN

Left and right legs of eight adult New Zealand rabbits were randomly assigned into either experimental or control groups to assess the effect of verapamil on SEA. Verapamil and normal saline were injected into the external iliac artery for experimental and control groups, respectively. The experiment was divided into two phases: Phase A investigated the immediate effect of verapamil on SEA of one active locus, and phase B studied the effect of verapamil on SEA of 25 different active loci. The average integrated value of SEA was used to statistically analyze the effect of verapamil on myofascial trigger-spot sensitivity.

RESULTS

In phase A, conducted on one active locus, the regression analysis results showed that the average integrated value in the verapamil group linearly decreased with time, but the average integrated value did not significantly change with time in the control group. In phase B, which analyzed 25 different active loci, the results indicated that the mean average integrated values in the verapamil group was significantly lower than that of the control group.

CONCLUSIONS

Calcium channel blockers can effectively inhibit the SEA of myofascial trigger spots.