Accuracy of nimodipine gel extraction

Until recently, use of nimodipine in aneurysmal subarachnoid hemorrhage patients unable to swallow required extraction of gel from inside the commercially available capsule. Despite the Black-Box warning against inadvertent intravenous administration, bedside extraction of the gel from the capsule continues to be a common practice in some institutions. The accuracy of bedside extraction has not been formally evaluated.

Twenty-eight nurses from the neurology and neurosurgical ICUs at a single center attempted to extract nimodipine gel from 2 capsules, each using the method currently approved by the US FDA. The primary outcome was mean weight of extracted gel per capsule, which was compared to both gel weight from batch compounded pharmacy syringes and a pre-calculated appropriate weight for 30 mg nimodipine gel.

Simulated bedside extraction provided lower yield than pharmacy-compounded syringes (22.6 ± 4.6 mg vs 30.4 ± 0.59 mg, p = 0.001). Bedside extraction provided inconsistent and low yield (75.4 ± 15.32 % of possible dose extracted, p = 0.0001 for comparison of means between bedside extraction syringes and predicted gel weight). Pharmacy-compounded syringes provided consistent high yield (101.3 ± 2.0 % of possible dose extracted, p = 0.14 for comparison of means between pharmacy syringes and predicted gel weight).

Combined with reports of significant patient harm and death with inadvertent intravenous administration, this study suggests that there is no role for bedside extraction of nimodipine in clinical practice.