Haloperidol Metabolite II Valproate Ester (S)-(-)-MRJF22: Preliminary Studies as a Potential Multifunctional Agent Against Uveal Melanoma.

Increased angiogenesis and vascular endothelial growth factor (VEGF) levels contribute to higher metastasis and mortality in uveal melanoma (UM), an aggressive malignancy of the eye in adults. (±)-MRJF22, a prodrug of the sigma (σ) ligand haloperidol metabolite II conjugated with the histone deacetylase (HDAC) inhibitor valproic acid, has previously demonstrated a promising antiangiogenic activity. Herein, the asymmetric synthesis of (R)-(+)-MRJF22 and (S)-(-)-MRJF22 was performed to investigate their contribution to (±)-MRJF22 antiangiogenic effects in human retinal endothelial cells (HREC) and to assess their therapeutic potential in primary human uveal melanoma (UM) 92-1 cell line. While both enantiomers displayed almost identical capabilities to reduce cell viability than the racemic mixture, (S)-(-)-MRJF22 exhibited the highest antimigratory effects in endothelial and tumor cells. Given the fundamental contribution of cell motility to cancer progression, (S)-(-)-MRJF22 may represent a promising candidate for novel antimetastatic therapy in patients with UM.

Concentration of Donepezil in the Cerebrospinal Fluid of AD Patients: Evaluation of Dosage Sufficiency in Standard Treatment Strategy.

Although some studies have described the pharmacokinetics and pharmacodynamics of donepezil in the peripheral compartment, studies focused on drug transport across the blood-brain barrier are still very rare. To our knowledge, the fluctuation in the cerebrospinal fluid concentration of donepezil after administration of the drug has not been described in the literature so far. We recruited 16 patients regularly taking a standard therapeutic dose of donepezil (10 mg per day). All patients (Caucasian race) were treated for at least three months with a stable dose of 10 mg per day prior to sample collection. Patients were divided into two groups depending on the time of plasma and cerebrospinal fluid sampling: 12 h (n = 9; 4 M/5F aged 78.68 ± 7.35 years) and 24 h (n = 7; 3 M/4F aged 77.14 ± 5.87 years) after donepezil administration. The cerebrospinal fluid sample was collected by standard lumbar puncture technique using a single-use traumatic needle. The samples were analysed on an Agilent 1260 Series liquid chromatograph comprising a degasser, a quaternary pump, a light-tight autosampler unit set, a thermostated column compartment, and a UV/VIS detector. Agilent ChemStation software, the statistical software Prism4, version 5.0 (GraphPad Software, USA), and IBM® SPSS® Statistics were used for the analysis of the results. The difference in plasma concentration of donepezil after 12 h (mean ± SEM; 39.99 ± 5.90 ng/ml) and after 24 h (29.38 ± 1.71 ng/ml) was nonsignificant. In contrast, the donepezil concentration in the cerebrospinal fluid was significantly higher in the 24-h interval (7.54 ± 0.55 ng/ml) compared with the 12-h interval (5.19 ± 0.83 ng/ml, which is ~70 % based on mean cerebrospinal fluid values). Based on these data, it is plausible to predict that donepezil might produce a stronger AChE inhibition in the brain at 24 h compared with 12 h following the administration. This information may help physicians individually adjust the time of drug administration in the patients according to time course of the disease symptoms.

No correlation between remifentanil blood, cerebrospinal fluid and cerebral extracellular fluid levels and TCI prediction: a pharmacokinetic study.

BACKGROUND: The aims of this paper were to elucidate the difference in concentration among remifentanil blood, cerebrospinal fluid and cerebral extracellular fluid levels, and to verify the presumable existence of a correlation between arterial and cerebral remifentanil. We used brain microdialysis to shed light on this aspect of the pharmacokinetic and to correlate these findings with Minto's model. METHODS: The study population was formed by 9 patients scheduled for elective intracranial surgery for cerebral supratentorial neoplasia. All patients received general anaesthetic; 100 microliters of dialysate were collected. Furthermore, arterial blood samples of 3 mL each were collected, respectively one at the beginning and one at the end of the sampling period. We determined the concentration of remifentanil and its main metabolite, remifentanil acid, in the blood and in the brain. The predictive performance of the Minto pharmacokinetic parameter set was evaluated by examining the performance error. RESULTS: The mean Performance Error was -45.13% (min -21.80, max -88.75) for the first series of arterial samples, -38.29% (min -6.57, max -79.17) for the second one and 67.73% (min 7, max -93.12) for the extra cellular fluid sample. The concentration of remifentanil set pumps was correlated with blood concentration for both series of samples. Neither the set concentration, nor the arterial samples were correlated with extra cellular fluid values. CONCLUSION: There was a wide interindividual variability with regard both to blood and cerebral remifentanil concentration. Moreover, the ratio between arterial blood and cerebral remifentanil was not consistent among our patients in spite of a stable infusion rate of remifentanil; at the end we found a trend of over prediction in the ratio between the various compartments examined.

Determination of crenolanib in human serum and cerebrospinal fluid by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS).

A LC-ESI-MS/MS method for the determination of crenolanib (CP-868,596) in human serum was developed and validated employing d4-CP-868,596 as an internal standard (ISTD). In addition to human serum, the method was also partially validated for crenolanib determination in human cerebrospinal fluid (CSF) samples. Sample aliquots (50µl of serum or CSF) were prepared for analysis using liquid-liquid extraction (LLE) with tert-butyl methyl ether. Chromatography was performed using a phenomenex Gemini C18 column (3µm, 100mm×4.6mm I.D.) in a column heater set at 50°C and an isocratic mobile phase (methanol/water/formic acid at a volume ratio of 25/25/0.15, v/v/v). The flow rate was 0.45mL/min, and the retention time for both analyte and ISTD was less than 3.5min. Samples were analyzed with an API-5500 LC-MS/MS system (ESI) in positive ionization mode coupled to a Shimadzu HPLC system. The ion transitions monitored were m/z 444.4→373.1 and m/z 448.2→374.2 for crenolanib and ISTD, respectively. The method was linear over the range of 5-1000ng/mL for serum and 0.5-1000ng/mL for CSF. For human serum, both intra-day and inter-day precision were <4%, while intra-day and inter-day accuracy were within 8% of nominal values. Recovery was greater than 50% for both the analyte and ISTD. For CSF samples, both intra-day and inter-day precision were <9% except at the lower limit of quantification (LLOQ) which was <17%. The intra-day and inter-day accuracy were within 11% of the nominal CSF concentrations. After validation, this method was successfully applied to the analysis of serial pharmacokinetic samples obtained from a child treated with oral crenolanib.

Determination of vandetanib in human plasma and cerebrospinal fluid by liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS).

A sensitive and precise LC-ESI-MS/MS method for the determination of vandetanib (ZD6474) in human plasma and cerebrospinal fluid (CSF) using [(13)C,d(3)]-ZD6474 as an internal standard (ISTD) was developed and validated. Sample preparation consisted of a simple liquid-liquid extraction with tert-butyl methyl ether containing 0.1% or 0.5% ammonium hydroxide. ZD6474 and ISTD were separated on a Kinetex C18 column (2.6 µm, 50 mm × 2.1 mm) at ambient temperature with an isocratic mobile phase (acetonitrile/10mM ammonium formate=50/50, v/v, at pH 5.0) delivered at 0.11 mL/min. The retention time of both compounds was at 1.60 min in a runtime of three min. Detection was achieved by an API-3200 LC-MS/MS system, monitoring m/z 475.1/112.1 and m/z 479.1/116.2 for vandetanib and ISTD, respectively. The method was linear in the range of 0.25-50 ng/mL (R(2) ≥ 0.990) for the CSF curve and from 1.0 to 3000 ng/mL (R(2) ≥ 0.992) for the plasma curve. The mean recovery for vandetanib was 80%. Within-day and between-day precisions were ≤ 8.8% and ≤ 5.9% for CSF and plasma, respectively. Within-day and between-day accuracies ranged from 95.0 to 98.5% for CSF, and from 104.0 to 108.5% for plasma. Analysis of plasma from six different sources showed no matrix effect for vandetanib (MF=0.98, %CV ≤ 4.97, n=6). This method was successfully applied to the analysis of pharmacokinetic samples from children with brain tumors treated with oral vandetanib.

Impact of peripheral elimination on the concentration-effect relationship of remifentanil in anaesthetized dogs.

BACKGROUND: This study elucidates the impact of sampling site when estimating pharmacokinetic-pharmacodynamic (PK-PD) parameters of drugs such as remifentanil that undergo tissue extraction in the biophase. The interrelationship between the concentrations of remifentanil predicted for the effect compartment and those measured in arterial, venous, and cerebrospinal fluid were investigated under steady-state conditions. METHODS: Following induction of anaesthesia with pentobarbital, an arterial cannula (femoral) and two venous catheters (jugular and femoral) were inserted. Electrodes were placed for EEG recording of theta wave activity. Each dog received two consecutive 5-min infusions for the PK-PD study and a bolus followed by a 60-min infusion was started for the steady-state study. Cerebrospinal fluid, arterial and venous blood samples were drawn simultaneously after 30, 40, and 50 min. At the end of the infusion, arterial blood samples were collected for pharmacokinetic analysis. RESULTS: Remifentanil PK-PD parameters based on theta wave activity were as follows: apparent volume of distribution at steady-state (V(ss)) (231+/-37 ml kg(-1)), total body clearance (Cl) (63+/-16 ml min(-1) kg(-1)), terminal elimination half-life (t(1/2 beta)) (7.71 min), effect compartment concentration at 50% of maximal observed effect (EC(50)) (21+/-13 ng ml(-1)), and equilibration rate constant between plasma and effect compartment (k(e0)) (0.48+/-0.24 min). The mean steady-state cerebrospinal fluid concentration of 236 ng ml(-1) represented 52 and 74% of that in arterial and venous blood, respectively. CONCLUSIONS: Our study re-emphasizes the importance of a sampling site when performing PK-PD modelling for drugs undergoing elimination from the effect compartment. For a drug undergoing tissue elimination such as remifentanil, venous rather than arterial concentrations will reflect more exactly the effect compartment concentrations, under steady-state conditions.

Preclinical neuropharmacology of naratriptan.

The basic CNS neuropharmacology of naratriptan is reviewed here. Naratriptan is a second-generation triptan antimigraine drug, developed at a time when CNS activity was thought not to be relevant to its therapeutic effect in migraine. It was, however, developed to be a more lipid-soluble, more readily absorbed and less readily metabolized variant on preexisting triptans and these variations conferred on it a higher CNS profile. Naratriptan is a 5-HT(1B/1D) receptor agonist with a highly selective action on migraine pain and nausea, without significant effect on other pain or even other trigeminal pain. Probable sites of therapeutic action of naratriptan include any or all of: the cranial vasculature; the peripheral terminations of trigeminovascular sensory nerves; the first-order synapses of the trigeminovascular sensory system; the descending pain control system; and the nuclei of the thalamus. Naratriptan may prevent painful dilatation of intracranial vessels or reverse such painful dilatation. Naratriptan can prevent the release of sensory peptides and inhibit painful neurogenic vasodilatation of intracranial blood vessels. At the first order synapse of the trigeminal sensory system, naratriptan can selectively suppress neurotransmission from sensory fibers from dural and vascular tissue, while sparing transmission from other trigeminal fibers, probably through inhibition of neuropeptide transmitter release. In the periaqueductal gray matter and in the nucleus raphe magnus, naratriptan selectively activates inhibitory neurons which project to the trigeminal nucleus and spinal cord and which exert inhibitory influences on trigeminovascular sensory input. Naratriptan has also a therapeutic effect on the nausea of migraine, possibly exerting its action at the level of the nucleus tractus solitarius via the same mechanisms by which it inhibits trigeminovascular nociceptive input. The incidence of naratriptan-induced adverse effects in the CNS is low and it is not an analgesic for pain other than that of vascular headache. In patients receiving selective serotonin uptake inhibitors (SSRIs) naratriptan may cause serotonin syndrome-like behavioral side effects. The mechanism of action involved in the production of behavioral and other CNS side effects of naratriptan is unknown.

Pharmacokinetic and safety assessments of concurrent administration of risperidone and donepezil.

Treatment of Alzheimer's disease sometimes uses combinations of drugs because dementia is frequently associated with behavioral symptoms. Risperidone and donepezil are both metabolized through cytochrome P450 2D6 and 3A4, raising the possibility of drug interactions with combination therapy. The objective of this study was to determine whether significant drug interactions occur with concomitant administration of donepezil and risperidone. In an open-label, three-way crossover study, 24 healthy men were randomly assigned to receive 0.5 mg of risperidone twice daily, 5 mg of donepezil once daily, or both drugs for 14 consecutive days, followed by a 21-day washout period. The treatment ratios of AUC and associated 90% confidence intervals (CIs) for risperidone active moiety, defined as risperidone plus 9-hydroxyrisperidone (ratio = 110.2%; 90% CI = 103.7-117.2), and for donepezil (ratio = 97.1%; 90% CI = 90.0-103.6) were within the 80% to 125% of bioequivalence range. The treatment ratios of Cmax and associated 90% CIs for risperidone active moiety (ratio = 114.6%; 90% CI = 107.0-122.8) and for donepezil (ratio = 96.1%; 90% CI = 90.0-102.6) were also within the bioequivalence range. Therefore, no significant pharmacokinetic differences occurred in either risperidone active moiety or donepezil when given alone or in combination. Adverse events (predominantly headache, nervousness, and somnolence) were minor and comparable for all treatment groups. The results indicate that no clinically meaningful drug interactions occurred between risperidone 1 mg daily and donepezil 5 mg daily at steady state, and therefore no dosage adjustment is required when both drugs are combined with the dosage regimen studied. Additional investigations are warranted to determine the potential for interactions in elderly patients with dementia who may eliminate risperidone and donepezil more slowly and thus be more vulnerable to clinical drug interactions than the young healthy subjects examined in this study.

Sensitive gas chromatographic-mass spectrometric method for the determination of gacyclidine in rat plasma and spinal cord dialyzates.

A sensitive gas chromatographic-mass spectrometric (GC-MS) procedure is described for the selective determination of gacyclidine (a non-competitive N-methyl-D-aspartate antagonist) in rat plasma and spinal cord dialyzates. It involves a single-step liquid-liquid extraction of plasma samples and dialyzates with hexane (pH 8.0) and the use of phencyclidine as an internal standard. The compounds were separated on a GC capillary column and specifically detected by MS in the selected-ion monitoring mode. Gacyclidine and its internal standard were monitored by using the fragment ions at m/z 206 and 200, respectively. The method was accurate and reproducible (intra- and inter-day reproducibility < 12%) with a limit of quantification of 1.6 ng ml-1 using 100 microliters plasma of dialyzate samples. The calibration curves for rat plasma and Ringer's solution were linear (r2 > 0.996) over a range from 1.6 to 200 ng ml-1. The extraction efficiency was close to 100%. This simple and rapid assay (total run time < 10 min) was validated for a pilot pharmacokinetic study in healthy rats after intravenous injection of a bolus dose of gacyclidine (2.5 mg kg-1).

Antinociceptive activity of CP-101,606, an NMDA receptor NR2B subunit antagonist.

1. The analgesic activity of CP-101,606, an NR2B subunit-selective N-methyl-D-aspartate (NMDA) receptor antagonist, was examined in carrageenan-induced hyperalgesia, capsaicin- and 4beta-phorbol-12-myristate-13-acetate (PMA)-induced nociceptive tests in the rat. 2. CP-101,606 30 mg kg(-1), s.c., at 0.5 and 2.5 h after carrageenan challenge suppressed mechanical hyperalgesia without any apparant alternations in motor coordination or behaviour in the rat. 3. CP-101,606 also inhibited capsaicin- and PMA-induced nociceptive responses (licking behaviour) with ED50 values of 7.5 and 5.7 mg kg(-1), s.c., respectively. 4. These results suggest that inhibition of the NR2B subunit of the NMDA receptor is effective in vivo at modulating nociception and hyperalgesia responses without causing the behavioural side effects often observed with currently available NMDA receptor antagonists.

AMPA, but not NMDA, receptor antagonism is neuroprotective in gerbil global ischaemia, even when delayed 24 h.

The selective alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) antagonist 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(f)quinoxaline (NBQX) and the selective N-methyl-D-aspartate (NMDA) receptor antagonists MK 801 and ifenprodil were administered to Mongolian gerbils following a 5 min period of bilateral carotid artery occlusion. NBQX when given 4, 6 or 24 h after ischaemia gave a reduced loss of hippocampal CA1 neurones compared to control animals receiving vehicle only. Dizocilipine (MK 801) (1-10 mg/kg i.p.) and ifenprodil (a total of 45 mg/kg i.p.) gave no protection. The peak levels of NBQX obtained in the cerebrospinal fluid of gerbils receiving the neuroprotective dose (3 x 30 mg/kg i.p.) was 1 microM. In gerbil cortex slices, this concentration had no effect on NMDA-evoked depolarization, but had a moderate effect on kainate and gave a total blockade of AMPA depolarizations. It is concluded that antagonists of non-NMDA glutamate receptor subtypes, possibly AMPA, may be a useful therapeutic approach for cerebral ischaemia-related brain damage following global ischaemia.

Ritanserin assessments in plasma and CSF by means of HPLC technique with fluorescence detection.

A specific HPLC-technique based on fluorescence detection was developed for assay of ritanserin, a serotonin receptor-blocking agent, in plasma and CSF. In 5 ml sample volumes, the limit of detection was 0.5 ng/ml, the recovery of ritanserin was 83 +/- 5%, and the inter-assay variability, expressed as the coefficient of variation, was 9.5% in the 2-788 ng/ml concentration range. When the values determined by this technique were compared with the results obtained by means of an independent HPLC-method with UV-detection, the coefficient of correlation was 0.995 (p less than 0.001). However, our technique proved to be more specific and less complicated.