LIDOCAINE

This anti-arrhythmic agent suppresses automaticity of conduction and spontaneous depolarisation of the ventricles during diastole. Clearance is related to both hepatic blood flow and hepatic function; it will be prolonged in liver disease, cardiac failure and the elderly. The effects after the initial bolus dose last about 20 min. An IV infusion is needed to maintain the anti-arrhythmic effect.

USES

Prevention of ventricular ectopic beats,VT and VF after MI

CONTRAINDICATIONS

• It is no longer the first-line drug in pulseless VT or VF during cardiac arrest

• Hypersensitivity to amide-type local anaesthetics (rare)

• Heart block (risk of asystole)

ADMINISTRATION

• Loading dose:

1.5 mg/kg IV over 2 min, repeat after 5 min to a total dose of

3 mg/kg if necessary. Reduce dose in the elderly

• Maintenance dose:

4 mg/min for 1st hour

2 mg/min for 2nd hour

1 mg/min thereafter

• Reduce infusion rates in patients with hepatic impairment, cardiac failure and in the elderly

• Undiluted 40 ml 2% solution (800 mg)

4 mg/min = 12 ml/h

2 mg/min = 6 ml/h

1 mg/min = 3 ml/h

Continuous ECG and BP monitoring

How not to use lidocaine

Do not give by rapid IV bolus (should not be given at >50 mg/min)

ADVERSE EFFECTS

• Paraesthesia,muscle twitching, tinnitus

• Anxiety, drowsiness, confusion, convulsions

• Hypotension, bradycardia, asystole

CAUTIONS

• Elderly (reduced volume of distribution, reduce dose by 50%)

• Hepatic impairment

• Cardiac failure

• Other class 1 anti-arrhythmics, e.g. phenytoin, may increase risk of toxicity

ORGAN FAILURE

Cardiac: reduce dose

Hepatic: reduce dose

OMEPRAZOLE

Omeprazole is a proton pump inhibitor (PPI) which inhibits gastric acid production by the gastric parietal cells.Following endoscopic treatment of bleeding peptic ulcers, omeprazole given intravenous for 72 hours has been shown to reduce the risk of rebleeding.

USES

• Bleeding peptic ulcers, after endoscopic treatment of bleeding (unlicensed)
• Continuation of PPI therapy when the PO/NG route is unavailable.
• Helicobacter pylori eradication.

ADMINISTRATION

• Bleeding peptic ulcers, after endoscopic treatment of bleeding

IV: Initial 80 mg IV loading dose given over 1 hour, followed by 8 mg/h
IV infusion for 72 hours
Reconstitute with either sodium chloride 0.9% or glucose 5%

• Continuation of PPI therapy when the PO/NG route is unavailable
IV bolus: 40 mg daily. Reconstitute 40 mg vial with the solvent provided and administer over 5 min
• Eradication of Helicobacter pylori

ADVERSE EFFECT

• GI disturbances (nausea, vomiting, abdominal pain, diarrhoea and constipation)
• Paraesthesia
• Agitation
• Liver dysfunction
• Hyponatraemia
• Leukopenia and thrombocytopenia rarely

CAUTIONS

• Severe hepatic disease (risk of encephalopathy)
• Pregnancy (toxic in animal studies)
• May mask symptoms of gastric cancer
• Omeprazole may enhance anticoagulant effect ofwarfarin – monitor INR and may increase phenytoin levels
• Omeprazole may reduce the effectiveness of clopidogrel

ORGAN FAILURE

Hepatic: reduce dose

Morphine

Morphine is the standard opioid with which others are compared and remains a valuable drug for the treatment of acute, severe pain.Peak effect after IV bolus is 15 min. Duration of action is between 2 and 3 hours. Both liver and kidney function are responsible for morphine elimination. The liver mainly metabolises it. One of the principal metabolites, morphine 6-glucuronide (M6G), is also a potent opioid agonist and may accumulate in renal failure.

USES

• Relief of severe pain
• To facilitate mechanical ventilation
• Acute left ventricular failure – by relieving anxiety and producing vasodilatation

CONTRAINDICATION

• Airway obstruction
• Pain caused by biliary colic

ADMINISTRATION

• IV bolus: 2.5 mg every 15 min PRN
• IV infusion rate: 1–5 mg/h

Dilute in glucose 5% or sodium chloride 0.9% 
Stop or reduce infusion each day and restart when first signs of discomfort appear. Failure to assess daily will result in overdosage and difficulty in weaning patient from ventilation

• If the patient is conscious the best method is to give an infusion pump they can control (PCAS): 50 mg made up to 50 ml with sodium chloride 0.9%; IV bolus: 1 mg; lockout: 3–10 min

How not to use morphine

In combination with an opioid partial agonist, e.g. buprenorphine (antagonises opioid effects)

ADVERSE EFFECTS

• Respiratory depression and apnoea
• Hypotension and tachycardia
• Nausea and vomiting
• Delayed gastric emptying
• Reduced intestinal mobility
• Biliary spasm
• Constipation
• Urinary retention
• Histamine release
• Tolerance
• Pulmonary oedema

CAUTIONS

Enhanced and prolonged effect when used in patients with renal failure, the elderly and in patients with hypovolaemia and hypothermia.
Enhanced sedative and respiratory depression from interaction with:
• benzodiazepines
• antidepressants
• anti-psychotics

Organ failure

• CNS: sedative effects increased
• Respiratory: respiratory depression
• Hepatic: can precipitate coma
• Renal: increased cerebral sensitivity. M6G accumulates

Renal replacement therapy

CVVH dialysed dose as in CC 10–20 ml/min, i.e. use smaller than usual dose, e.g. 2.5–5 mg. HD dialysed dose as in CC 10 ml/min, i.e. use smaller doses, e.g. 1.25–2.5 mg and extended dosing intervals. PD not dialysable, dose as per HD. Active metabolite M6G accumulates in renal failure.Titrate to response, such as pain/sedation scores.