The effects of verapamil on cerebrospinal fluid pressure in surgical patients

Modeling of the effect of cerebrospinal fluid flow modulation on locally delivered drugs in the brain

Cerebrospinal fluid (CSF) plays a vital role in maintaining brain homeostasis and recent research has focused on elucidating the role that convective flow of CSF plays in brain health. This paper describes a computational compartmental model of how CSF dynamics affect drug pharmacokinetics in the rat brain. Our model implements a local, sustained release approach for drug delivery to the brain. Simulation outputs highlight the potential for modulating CSF flow to improve overall drug pharmacokinetics in the central nervous system and suggest that concomitant CSF modulation and optimized drug release rates from implantable depots can be used to engineer the duration of action of chemotherapeutics. As an example, the tissue exposure of temozolomide, the standard of care treatment for glioblastoma, was modeled in conjunction with two CSF-modulating drugs: acetazolamide and verapamil. Simulations indicate that temozolomide exposure in the interstitial fluid is increased by 25% when using local sustained release delivery systems and concomitant acetazolamide delivery to reduce CSF production. This computational model can be used to produce insight on how to appropriately modulate CSF production and engineer drug release to tailor drug exposure in the brain while limiting off-target effects. As new research continues to elucidate the dynamic roles of CSF, this model can be further improved and leveraged to provide information on how CSF modulation may play a beneficial role in treating a wide variety of neurological disease.

Attenuation of the pressor response to laryngoscopy and tracheal intubation with intravenous verapamil

This study was undertaken in surgical patients in order to evaluate the effects of intravenous verapamil on the circulatory responses to laryngoscopy and tracheal intubation. Laryngoscopy for tracheal intubation was initiated 1 min after thiamylal 5 mg.kg-1 and succinylcholine 1.5 mg.kg-1 in the control group (n = 21). The verapamil group (n = 23) received intravenous verapamil 0.1 mg.kg-1 immediately after thiamylal-succinylcholine administration. The resulting changes in mean arterial pressure (MAP) and heart rate (HR) were continuously measured. Compared with the control group, MAP increased less in response to laryngoscopy and tracheal intubation (56 +/- 13% versus 25 +/- 15% above baselines, P less than 0.01) and returned toward baseline sooner in patients receiving verapamil. For hypertensive patients, MAP increases from baseline after intubation were 18 +/- 9% in the verapamil group, and 53 +/- 14% in the control group, respectively (P less than 0.001). Increases in HR response to laryngoscopy for intubation were comparable in both groups. We conclude that intravenous verapamil is effective in reducing pressor responses during endotracheal intubation, especially in hypertensive patients.