Lead author Rumiko Hosokawa and his team from the Department of Dental Anesthesiology, Faculty of Dental Science, Kyushu University, Maidashi, Higashi-ku, Fukuoka, Japan, explored the potential role that gabapentin may play as a preanesthetic medication administered prior to IV sedation (IVS) with propofol. A structural analogue of the inhibitory neurotransmitter gamma-aminobutyric acid, gabapentin has been used as an anticonvulsant with additional analgesic qualities.  Less well known, however, is gabapentin’s ability to offer an enhanced benefit of sedation, especially during IVS.

The small study included 10 subjects who underwent propofol IVS three times, each administration given once on three different days. On the first day, propofol IVS was administered without gabapentin (serving as control), and on the two subsequent days, gabapentin was administered, with Day 2 associated with a 200-mg dose and Day 3 associated with a 400-mg dose administered 3 hours prior to IVS, respectively. The target blood concentration of propofol was gradually increased, and at each target concentration, assessment scores were evaluated and subjects were monitored for changes in vital signs or other potential complications.

The assessment scores used by researchers included the Ramsay Sedation Score (RSS), which ranged from RSS 1 (anxious/agitated/restless) to RSS 6 (sedated with no response). In addition to the enhanced sedating effects, patients’ vital signs and any other potential postanesthetic complications were also recorded. Researchers found that the target blood concentration of propofol, when coadministered with 400 mg gabapentin, was significantly reduced at RSS 3, 4, 5, and 6 (P = .040, P = .004, P = .001, and P = .004, respectively), but that no significant difference in propofol target blood concentrations was seen either with the 200-mg dose or when no gabapentin was coadministered.

The authors noted, “To our knowledge, this is the first study to investigate the effectiveness of oral administration of gabapentin on sedative action during IVS using propofol target controlled infusion.” They further declared that in addition to a significantly reduced amount of propofol required to obtain acceptable and adequate sedation in IVS, no remarkable changes in respiration and circulation were observed. In addition, the authors reported that patients did not experience any complications associated with the additional preanesthetic gabapentin administration.

The authors concluded that oral administration of gabapentin 400-mg reduced the target blood concentration of propofol required to achieve an adequate sedation level estimated by RSS on IVS. However, the researchers also caution that further trials are needed to ensure appropriate and meaningful use of gabapentin in clinical anesthesia.

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