Background
Mirtazapine is an antidepressant drug that blocks central 5-HT2 receptors with anxiolytic and sleep-promoting effects and theoretically can be used as a premedication.
Methods
Sixty ASA I-II patients aged 25–50 yr were randomly allocated according to the premedication received 2 h before induction of anesthesia into two equal groups: group M patients received mirtazapine 30 mg tablet mixed with 20 ml of water and group P patients received 20 ml of plain water. Anxiety level was measured by visual analogue scale (VAS) and bispectral index (BIS) electrodes were connected before induction of anesthesia. Intravenous (i.v) infusion of propofol 1% at a rate of 300 ml h was started to induce hypnosis till a target BIS value of 45 (BIS45) is reached, and then endotracheal intubation is performed after fentanyl and cis-atracuruim being administered. Propofol dose requirements to achieve loss of response to verbal contact (RVC), loss of eyelash reflex (ELR), and a target BIS45 were recorded. Anesthesia was maintained with sevoflurane titrated to BIS value of 40–50 and oxygen/air mixture. Recovery time was recorded. In postanaesthesia care unit (PACU), VAS for pain and Ramsay sedation score were recorded. Patients were discharged from PACU when two consecutive Aldrete scores of 9 or 10 are obtained, and time of PACU stay was recorded.
Results
Preoperative anxiety by VAS and propofol doses required achieving loss of RVC and ELR, and target BIS45 were significantly lower in mirtazapine group. The two groups were comparable with regard to recovery and PACU stay times as well as postoperative pain and anxiety.
Conclusion
Mirtazapine 30 mg oral tablets can be used as a premedication as it reduces preoperative anxiety and hypnotic dose requirements of propofol, and does not prolong recovery time.