Compare and contrast ketamine and midazolam

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College Answer

In addition to the key PK and PD properties of each drug, a clear comparison was required to score well (why choose one drug over the other?). When a table was used the addition of a comparison column was helpful.

A good answer covered the following: ketamine has analgesic properties whilst midazolam does not; ketamine preserves airway reflexes and does not cause respiratory depression unlike midazolam; whilst ketamine increases cerebral blood flow and CMRO2, midazolam decreases it; ketamine has a direct myocardial depressant effect which is often offset by an increase in sympathetic tone, whilst midazolam has no direct cardiac depressant effects but may reduce BP due to reduced SVR; midazolam has anticonvulsant properties, ketamine does not; ketamine is a bronchodilator; both drug effects are offset by redistribution; midazolam is lipophillic at body pH and will accumulate with prolonged infusions, ketamine will not; both are metabolised in the liver; midazolam can be reliably reversed by flumazenil, whereas there is no reliable complete reversal of ketamine; midazolam exhibits tolerance, dependence and withdrawal, whereas patients will only experience tolerance to the analgesic properties of ketamine. “

Drugs in Anaesthesia and Intensive care” chapters on midazolam and ketamine outline the key facts to include in this answer; interpretation and comparison of these facts will help achieve a good mark.