Mass spectrometry-based method for quantification of nimodipine and glutamate in cerebrospinal fluid. Pilot study with patients after aneurysmal subarachnoid haemorrhage.

WHAT IS KNOWN AND OBJECTIVE: Delayed cerebral ischaemia is an important cause of morbidity and mortality after aneurysmal subarachnoid haemorrhage (aSAH). Nimodipine is the only drug approved by the FDA for improving outcome after aSAH. Clinically, however, there are no specific values of this drug in cerebrospinal fluid (CSF) during aSAH treatment that could be associated to outcome improvement. Furthermore, the neurotransmitter glutamate acts as a secondary marker for brain injury. The aim was to establish a method to measure nimodipine and glutamate concentrations simultaneously in CSF of patients after aSAH. METHODS: From June 2017 to June 2018, we prospectively collected clinical data of patients with aSAH admitted to our neurointensive care unit. All included patients received nimodipine orally (60 mg every 4 hours). Patients, who developed clinical vasospasm during their in-hospital stay, underwent intra-arterial application of nimodipine (IAN), followed by angiographic control. A method using high-performance liquid chromatography coupled with mass spectrometric analysis (LC-MS/MS) was established for quantification of both analytes in CSF. RESULTS AND DISCUSSION: In 15 (60%) of 25 patients, nimodipine and glutamate concentrations were measured. After IAN for treatment of vasospasms, CSF nimodipine concentrations were slightly higher than in patients who received nimodipine only orally (0.60 ± 0.27 ng/mL vs 0.48 ± 0.18 ng/mL). Patients developing vasospasm exhibited higher glutamate concentrations than patients without vasospasm (188.84 ng/mL vs136.07 ng/mL). WHAT IS NEW AND CONCLUSION: The developed method allowed the simultaneous quantification of nimodipine and glutamate in CSF. Furthermore, we demonstrated that IAN resulted in higher concentrations in CSF, when compared to oral application only.

Lack of Antiparkinsonian Effects of Systemic Injections of the Specific T-Type Calcium Channel Blocker ML218 in MPTP-Treated Monkeys.

Dopaminergic medications ameliorate many of the motor impairments of Parkinson's disease (PD). However, parkinsonism is often only partially reversed by these drugs, and they can have significant side effects. Therefore, a need remains for novel treatments of parkinsonism. Studies in rodents and preliminary clinical evidence have shown that T-type calcium channel (TTCC) antagonists have antiparkinsonian effects. However, most of the available studies utilized nonselective agents. We now evaluated whether systemic injections of the specific TTCC blocker ML218 have antiparkinsonian effects in MPTP-treated parkinsonian Rhesus monkeys. The animals were treated chronically with MPTP until they reached stable parkinsonism. In pharmacokinetic studies, we found that ML218 reaches a peak CSF concentration 1-2 h after s.c. administration. In electrocardiographic studies, we found no effects of ML218 on cardiac rhythmicity. As expected, systemic injections of the dopamine precursor L-DOPA dose-dependently increased the movements in our parkinsonian animals. We then tested the behavioral effects of systemic injections of ML218 (1, 10, or 30 mg/kg) or its vehicle, but did not detect specific antiparkinsonian effects. ML218 (3 or 10 mg/kg) was also not synergistic with L-DOPA. Using recordings of electrocorticogram signals (in one animal), we found that ML218 increased sleep. We conclude that ML218 does not have antiparkinsonian effects in MPTP-treated parkinsonian monkeys, due at least in part, to the agent's sedative effects.

Simple and validated UHPLC-MS/MS analysis of nimodipine in plasma and cerebrospinal fluid of patients with subarachnoid haemorrhage.

We present a simple, fast and validated method for the determination of nimodipine in plasma and cerebrospinal fluid (CSF) of patients with subarachnoid haemorrhage using ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Plasma or CSF 250µL aliquots were pretreated with acetonitrile spiked with lacosamide as internal standard. The chromatographic separation was performed on a Fusion (3µm) 50×2.0mm I.D. column with gradient elution of 0.1% (v/v) formic acid in water and 0.1% (v/v) formic acid in acetonitrile at a flow rate of 0.35mL/min. The MS/MS ion transitions were 419.1→343 for nimodipine and 251.1→91 for the internal standard. The linearity was determined from 2.0 to 40.0ng/mL in plasma and 40.0-800.0pg/mL in CSF. The lower limit of quantitation (LLOQ) of nimodipine was 0.4ng/mL in plasma and 40pg/mL in CSF. The mean recovery for nimodipine was ≥75% in plasma and ≥90% in CSF at all three considered concentrations. Intra- and interassay precision and accuracy were ≤15% at all quality control concentrations in plasma and CSF. The method was applied to measure plasma and CSF concentrations of nimodipine in a series of patients with subarachnoid haemorrhage treated with intravenous nimodipine. The present procedure, omitting time-consuming liquid-liquid extraction and drying steps, is faster, simpler and cheaper than published LC-MS/MS analytical methods for nimodipine in plasma and the first validated one for nimodipine in CSF.

Absorption, elimination and cerebrospinal fluid concentrations of nimodipine in healthy beagle dogs receiving human intravenous and oral formulation.

Nimodipine is an L-type calcium channel blocker and is used to treat vasospasm in patients with subarachnoid hemorrhage. Its putative mechanism of action is relaxation of smooth muscle cells in cerebral arteries. In addition, nimodipine may have pleiotropic effects against vasospasm. Systemic hypotension is an adverse effect when patients are treated with oral or intravenous nimodipine. Intracranial administration of nimodipine formulations may produce higher concentration of nimodipine in the cerebrospinal fluid (CSF) than is possible to achieve orally or intravenously, while resulting in lower incidence of systemic hypotension. The aim of this study was to provide information on plasma and CSF levels of nimodipine in beagle dogs as a comparative data for development of experimental intracranial treatment modalities. Plasma levels of nimodipine were measured after current 30 and 60 mg single oral dose of nimodipine (Nimotop(®) 30 mg tablets), a single intravenous bolus 0.72 mg/dog of nimodipine (Nimotop(®) 0.2 mg/ml infusion solution) and CSF levels after 60 mg single oral dose of nimodipine. CSF/Plasma concentration ratio of nimodipine after oral administration of 60 mg at 1 h was 0.013 ± 0.0005. The mean terminal elimination half-life of nimodipine after i.v. bolus dose 0.72 mg was 1.8 h and mean plasma clearance was 40.3 and 3.4 l/h/kg. Absolute bioavailability was 22 %. Maximum plasma concentration and area under the plasma concentration-time curve from time of administration until the last measurable plasma concentration increased in a dose-proportional manner comparing the exposure parameters at oral doses of 30 and 60 mg. Individual variation in the kinetic profile of nimodipine was measured.

Pharmacokinetic analysis of ziconotide (SNX-111), an intrathecal N-type calcium channel blocking analgesic, delivered by bolus and infusion in the dog.

BACKGROUND AND PURPOSE: Ziconotide is a peptide that blocks N-type calcium channels and is antihyperalgesic after intrathecal (IT) delivery. We here characterize the spinal kinetics of IT bolus and infused ziconotide in dog. EXPERIMENTAL APPROACH: Male beagle dogs (N= 5) were prepared with chronic IT lumbar injection and cerebrospinal fluid (LCSF) sampling catheters connected to vest-mounted pumps. Each dog received the following: 1) IT bolus ziconotide (10 µg + 1 µCi (3) H-inulin); 2) IT infusion for 48 hours of ziconotide (1 µg/100 µL/hour); 3) IT infusion for 48 hours of ziconotide (5 µg/100 µL/hour); and 4) intravenous injection of ziconotide (0.1 mg/kg). After IT bolus, LCSF ziconotide and inulin showed an initial peak and biphasic (distribution/elimination) clearance (ziconotide T(1/2-α/ß) = 0.14 and 1.77 hours, and inulin T(1/2-α/ß) = 0.16 and 3.88 hours, respectively). The LCSF : plasma ziconotide concentration ratio was 20,000:1 at 30 min and 30:1 at eight hours. IT infusion of 1 and then 5 µg/hour resulted in LCSF concentrations that peaked by eight hours and remained stable at 343 and 1380 ng/mL, respectively, to the end of the 48-hour infusions. Terminal elimination T(1/2) after termination of continuous infusion was 2.47 hours. Ziconotide LCSF : cisternal CSF : plasma concentration ratios after infusion of 1 and 5 µg/hour were 1:0.017:0.001 and 1:0.015:0.003, respectively. IT infusion of ziconotide at 1 µg/hour inhibited thermal skin twitch by 24 hours and produced modest trembling, ataxia, and decreased arousal. Effects continued through the 48-hour infusion period, increased in magnitude during the subsequent 5 µg/hour infusion periods, and disappeared after drug clearance. CONCLUSIONS AND IMPLICATIONS: After IT bolus or infusion, ziconotide displays linear kinetics that are consistent with a hydrophilic molecule of approximately 2500 Da that is cleared slightly more rapidly than inulin from the LCSF. Behavioral effects were dose dependent and reversible.

Prophylactic intravenous nimodipine treatment in skull base surgery: pharmacokinetic aspects.

BACKGROUND: Nimodipine is primarily used in subarachnoid hemorrhage (SAH). Clinical trials revealed also a beneficial effect of prophylactic nimodipine treatment on cranial nerve functions following vestibular schwannoma surgery. OBJECTIVE: The unknown pharmacokinetics of prophylactically administered nimodipine were investigated. METHODS: Samples were taken from 27 patients with skull base lesions. Prophylactic intravenous nimodipine infusion was started 5.8-25.8 h (mean 17.9 h) before surgery. Nimodipine concentrations were determined in serum (intra- and postoperatively), cerebrospinal fluid (CSF) (intraoperatively), and tissue samples. RESULTS: Wide interindividual differences were observed. Mean concentrations for nimodipine were 46.9 ng/ml (SD: 6.4; min. 4.1 and max. 92.7 ng/ml) in intraoperative serum, 73.2 ng/ml (SD: 16.7; min. 6.6 and max. 253 ng/ml) in postoperative serum and 8.3 ng/ml (SD: 1.5; min. 1.0 und max. 29.7 ng/ml) in intraoperative CSF. The correlation between intra- and postoperative serum (p=0.004, r=0.560) and between intra-operative serum and CSF concentration (p=0.003, r=0.567) were statistically significant. Furthermore the correlation between intraoperative serum concentration and concentrations collected from vestibular nerves was high (r=0.711), but not statistically significant (p=0.178). CONCLUSIONS: Interindividually, continously administered intravenous nimodipine produces considerably variable serum levels. Controls of nimodipine serum concentrations may be useful to optimize nimodipine medication in skull base surgery and in the management of SAH. The serum nimodipine level is a useful marker for CSF and intracranial nerve tissue concentrations of nimodipine.

Add-on treatment with verapamil in pharmacoresistant canine epilepsy.

PURPOSE: Verapamil add-on treatment has been suggested as a novel therapeutic concept for overcoming transporter-mediated pharmacoresistance. Efficacy data have been limited so far to case reports in individual epileptic patients. Therefore, we aimed to thoroughly evaluate the efficacy and tolerability of verapamil add-on treatment. METHODS: In a prestudy in healthy Beagle dogs the tolerability of verapamil add-on treatment was investigated. The efficacy of verapamil was then evaluated in 11 dogs with phenobarbital-resistant epilepsy. KEY FINDINGS: Verapamil add-on treatment (6.2-7.3 mg/kg) did not affect phenobarbital concentrations in plasma or cerebrospinal fluid. Side effects observed in healthy as well as in epileptic dogs comprised bradycardia and a decrease in blood pressure. Therefore, we had to limit the dosage to 1-1.5 mg/kg in the main study. In phenobarbital nonresponders, verapamil failed to improve seizure control. Verapamil treatment was discontinued prematurely in five animals due to worsening of seizure control or lack of an effect. In the remaining animals, seizure frequency tended to increase during the verapamil add-on phase, reaching a mean of two seizures per month compared to the pre-verapamil phase with phenobarbital monotherapy (mean of 1.4 seizures per month). In view of the detrimental effects in the majority of the dogs, the study had to be discontinued and no further animals were enrolled. SIGNIFICANCE: The failure of the maximum tolerated dosage to improve seizure control in dogs with phenobarbital-resistant epilepsy argues against the suitability of verapamil add-on treatment to overcome pharmacoresistance. Deterioration of seizure control in some individual animals suggests that verapamil might also exert unfavorable effects on seizure thresholds or its spread.

Preparation of nimodipine-loaded microemulsion for intranasal delivery and evaluation on the targeting efficiency to the brain.

The purpose of this study was to improve the solubility and enhance the brain uptake of nimodipine (NM) in an o/w microemulsion, which was suitable for intranasal delivery. Three microemulsion systems stabilized by the nonionic surfactants either Cremophor RH 40 or Labrasol, and containing a variety of oils, namely isopropyl myristate, Labrafil M 1944CS and Maisine 35-1 were developed and characterized. The nasal absorption of NM from microemulsion formulation was investigated in rats. The optimal microemulsion formulation consisted of 8% Labrafil M 1944CS, 30% Cremophor RH 40/ethanol (3:1) and water, with a maximum solubility of NM up to 6.4 mg/ml, droplet size of 30.3 +/- 5.3 nm, and no ciliotoxicity. After a single intranasal administration of this preparation at a dose of 2 mg/kg, the plasma concentration peaked at 1 h and the absolute bioavailability was about 32%. The uptake of NM in the olfactory bulb from the nasal route was three folds, compared with intravenous (i.v.) injection. The ratios of AUC in brain tissues and cerebrospinal fluid to that in plasma obtained after nasal administration were significantly higher than those after i.v. administration. These results suggest that the microemulsion system is a promising approach for intranasal delivery of NM for the treatment and prevention of neurodegenerative diseases.

Distribution of nimodipine in brain following intranasal administration in rats.

AIM: To determine whether nasally applied nimodipine (NM) could improve its systemic bioavailability and be transported directly from the nasal cavity to the brain. METHODS: NM was administered nasally, intravenously (iv), and orally to male Sprague-Dawley rats. At different times post dose, blood, cerebrospinal fluid (CSF), and brain tissue samples were collected, and the concentrations of NM in the samples were analyzed by HPLC. RESULTS: Oral systemic bioavailability of NM in rats was 1.17 %, nasal dosing improved bioavailibility to 67.4 %. Following intranasal administration, NM concentrations in olfactory bulb (OB) within 30 min post dose were found significant higher than in the other brain tissues. However, similar NM levels in different brain regions were observed after iv injection. AUC in CSF and OB from the nasal route was 1.26 and 1.39 fold compared with the iv route, respectively. The brain-to-plasma AUC ratios were significantly higher after nasal administration than after iv administration (P<0.01). CONCLUSION: Nasally administered NM could markedly improve the bioavailability and a fraction of the NM dose could be transported into brain via the olfactory pathway in rats.

Nimodipine transfer into human breast milk and cerebrospinal fluid.

OBJECTIVE: To report nimodipine concentrations in breast milk and cerebrospinal fluid (CSF) of a lactating woman who was given the drug to prevent a vascular spasm secondary to angiographic examination. METHODS: A 36-year-old woman received a total dose of nimodipine 46 mg iv over 24 hours. She extracted milk when she noted mammary tightness, and blood samples were taken simultaneously by venipuncture in the arm contralateral to that of the nimodipine infusion. A CSF sample also was taken in a diagnostic lumbar puncture. RESULTS: Nimodipine concentration in milk was much lower than that in serum, with a milk/serum ratio of 0.06-0.15. The CSF/serum ratio was 0.01. We estimate that the infant would have received between 0.008% and 0.092% of the weight-adjusted dose that was administered to the mother if the baby had been nursed. CONCLUSIONS: Nimodipine is transferred to human milk in a lower proportion than are other calcium-channel blockers. These results suggest that treating the mother with nimodipine would entail no risk to the nursing infant.