Anaesthesia interactions with other drugs

It is generally recommended that MAOIs should be withdrawn at least 2 weeks before anaesthesia. Individual cases of both hypo-and hypertension have been seen and MAOIs can interact dangerously with other drugs sometimes used during surgery (particularly pethidine (meperidine) and ephedrine). 

A study in 6 healthy subjects receiving 30-hour infusions of lidocaine at a rate of 2 mg/minute found that pretreatment with propranolol 80 mg every 8 hours for 3 days raised the steady-state plasma lidocaine levels by 19% (from 2.1 to 2.5 micrograms/mL) and reduced the plasma clearance by 16%. Other similar studies have found a 22.5 to 30% increase in steady-state serum lidocaine levels and a 14.7 to 46% fall in plasma clearance due to the concurrent use of propranolol. Two cases of lidocaine toxicity attributed to a lidocaine-propranolol interaction were revealed by a search of the FDA adverse drug reaction file in 1981. A further case of lidocaine toxicity (seizures) has been described in a man on propranolol after accidental oral ingestion of lidocaine for oesophageal anaesthesia. High serum levels of lidocaine were detected. ... 

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