Introduction
- Lidocaine is an amide local anaesthetic that is a non-selective sodium channel blocker
- Acts by suppressing ectopic neural discharges originating from injured afferent fibres by blocking sodium channels – damaged neurons more sensitive to Lidocaine
- Also has effects on brain sodium channels
- Does not have any effect on the normal function of other sensory/motor neurones
- Has effect on lowering susceptibility to all types of pain
- Activates endogenous opioid system
Pharmacology
a) Indications
- Neuropathic pain
a) Difficult pain not responding to other analgesics
b) In terminal phase
- Any difficult pains not responding to optimal treatment.
b) Contraindications
- hepatic disease
- cardiac arrhythmias, complete block
- Epilepsy
- cautions: epilepsy, shock brady cardia
c) Drug Interactions
- other anaesthetics
- antiarrhythmic drugs
- increased risk with drugs that prolong QT interval
- Beta Blockers
- Cimtidine
d) Available Preparations
1% Lidocaine hydrochloride 10mg/ml – 2,5,10,20ml
2% Lidocaine Hydrochloride 20mg/ml – 2,5ml
e) Side Effects
- Light-headedness, dizziness, somnolence increases risk with perianal numbness increasing dose
- Headache
- Respiratory depression
- Hallucinations
- Seizure
Guidelines
a) Administration/Dose
i) occasionally given IV as test dose equates to +100mg per day 1-5mg/kg (usual starting dose)
ii) pulse therapy (CSCI)
given via CSCI over 6-24 hours
increase by 100mg/day until response obtained
once response obtained continue at same dose for 5 days then stop infusion
can repeat infusion when pain returns
maximum dose 600mg/24hours
b) Prevention of Side Effects
- Consider reduction of opioids when commencing Lidocaine
- No oral equivalent to Lidocaine but good response may suggest that oral
- Mexilitine could be effective in maintaining analgesic control
Monitoring During Treatment
Baseline and then half hourly for first 2 hours, then 4 hourly thereafter:
- Heart rate/pulse
- Respiratory rate
- BP
- ECG – repeat ECG with each increase in dose or significant alteration in heart rate or rhythm
- O2 sats – if less than 90% consider treatment whilst on O2 to maintain saturation at less than 95%
- If any significant changes in observations notify doctors ASAP
References/Bibliography
Attal 2000
Attal 2004
Jauren Mae 2000
Cahara 2004
Kvanstrom & Karlsten 2003
Kvanstrom & Karlsen 2004
Ferrine (JPM) 2000
Tremont-Luklats et al 2005
BNF