Reversal of cerebral vasospasm using an intrathecally administered nitric oxide donor.

OBJECT: Intrathecal bolus administration of (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)aminio]diazen++ +-1-ium-1,2-diolate (DETA/NO), a long half-life diazeniumdiolate-class nitric oxide (NO) donor, was evaluated for safety and efficacy in the treatment of delayed cerebral vasospasm in a canine model of subarachnoid hemorrhage (SAH). METHODS: The baseline basilar artery (BA) diameter of 25 dogs was measured with the aid of angiography on Day 0. Vasospasm was then induced by intracisternal injection of autologous arterial blood on Days 0 and 2. Repeated arteriography on Day 7 revealed an average BA diameter of 58% of baseline. Each dog was then randomized to one of four groups: a pathology control group (SAH only, four animals); a treatment control group (SAH plus 2 micromol of the inactive drug carrier DETA, eight animals); a low-dose treatment group (SAH plus 0.2 micromol DETA/NO, six animals); or a high-dose treatment group (SAH plus 2 micromol DETA/NO, six animals). The drugs were administered in a 2-ml intrathecal bolus via the cisterna magna. Arterial caliber was monitored by angiography over the subsequent 4 hours. A 2-micromol dose of the drug was then given and serial arteriography continued for an additional hour to screen for tachyphylaxis. Intracranial pressure and respiratory and hemodynamic parameters were continuously monitored. Histopathological analyses of the animals' brains were performed after the dogs were killed on Day 8. The drug DETA/NO produced reversal of vasospasm in a dose-dependent fashion that roughly followed a double exponential time course. Doses of 2 micromol DETA/NO resulted in restoration of the angiographically monitored BA diameter to the prevasospasm size at 1.5 hours posttreatment, and this was sustained at 88% of baseline at 4 hours (p < 0.01, independent samples t-test). By contrast, the treatment control group remained on average at 54% of baseline diameter. The low-dose treatment group achieved only partial and more transitory relaxation. Histopathological analyses showed findings consistent with chronic SAH but did not demonstrate any toxicity associated with the NO donor. No adverse physiological changes were seen. CONCLUSIONS: This study indicates that long-acting NO donors are potentially useful as agents to restore circulation in patients suffering from cerebral vasospasm.

Capillary reversed-phase high-performance liquid chromatographic determination of acetyl-methylprednisolone in feline spinal cord.

Capillary reversed-phase high-performance liquid chromatography (RP-HPLC) was used to determine acetylmethylprednisolone (A-MP) that had been administered to feline spinal cord tissue. The method used a 300 mm x 0.32 mm I.D. packed capillary octadecylsilyl (ODS) column and an isocratic mobile phase of 40 mM triethylamine formate (TEAF, pH 3.2)-acetonitrile (50:50, v:v). The chromatographic behavior of A-MP was evaluated with respect to peak-area and peak-height by varying the A-MP concentration (12-190 microM) with a fixed injection volume (1 microliter), and by varying the injection volume (1-10 microliter) with a fixed concentration (12 microM) of A-MP. The limit of detection (signal-to-noise ratio, 3:1) was 250 pg (600 fmol) of synthetic A-MP. Various amounts of A-MP directly spiked into feline spinal cord segments were solvent extracted, separated, and plotted against peak-area (r2 = 1.00). Background tissue without A-MP gives minimal (< 1%) interference at 243 nm. The method also detects exogenous A-MP that was administered into feline spinal cord via an intrathecal injection. Furthermore, the presence of A-MP was confirmed via its molecular ion and corresponding product ions that were obtained by fast-atom bombardment tandem mass spectrometry (FAB-MS-MS).