Pharmaceutical Differences Between Block Copolymer Self-Assembled and Cross-Linked Nanoassemblies as Carriers for Tunable Drug Release

Purpose

To identify the effects of cross-linkers and drug-binding linkers on physicochemical and biological properties of polymer nanoassembly drug carriers.

Methods

Four types of polymer nanoassemblies were synthesized from poly(ethylene glycol)-poly(aspartate) [PEG-p(Asp)] block copolymers: self-assembled nanoassemblies (SNAs) and cross-linked nanoassemblies (CNAs) to each of which an anticancer drug doxorubicin (DOX) was loaded by either physical entrapment or chemical conjugation (through acid-sensitive hydrazone linkers).

Results

Drug loading in nanoassemblies was 27?~?56% by weight. The particle size of SNA changed after drug and drug-binding linker entrapment (20?~?100 nm), whereas CNAs remained 30?~?40 nm. Drug release rates were fine-tunable by using amide cross-linkers and hydrazone drug-binding linkers in combination. In vitro cytotoxicity assays using a human lung cancer A549 cell line revealed that DOX-loaded nanoassemblies were equally potent as free DOX with a wide range of drug release half-life (t_1/2?=?3.24?~?18.48 h, at pH 5.0), but 5 times less effective when t_1/2?=?44.52 h.

Conclusion

Nanoassemblies that incorporate cross-linkers and drug-binding linkers in combination have pharmaceutical advantages such as uniform particle size, physicochemical stability, fine-tunable drug release rates, and maximum cytotoxicity of entrapped drug payloads.     

Pharmacokinetics and Pharmacodynamics of the Antiplatelet Combination Aspirin (Acetylsalicylic Acid) Plus Extended-Release Dipyridamole Are Not Altered by Coadministration with the Potent CYP2C19 Inhibitor Omeprazole

Background

The fixed-dose combination of aspirin (acetylsalicylic acid) 25 mg plus extended-release dipyridamole 200 mg (ASA + ER-DP) is used for long-term secondary stroke prevention in patients who have experienced non-cardioembolic stroke or transient ischemic attack. Although the theoretical risk is low that the antiplatelet activity of ASA + ER-DP will be affected by concomitant use of a proton pump inhibitor (PPI), no formal drug-drug interaction studies have been conducted.

Objective

This study aimed to determine whether the PPI omeprazole influences the pharmacokinetic (PK) and pharmacodynamic (PD) behavior of ASA + ER-DP.

Study Design and Setting

This was a randomized, open-label, multiple-dose, crossover, drug-drug interaction study carried out in a clinical trial unit.

Participants

Sixty healthy male and female volunteers aged 18–50 years were included in the study.

Intervention

Participants were randomized to one of two treatment sequences (ABCD or CDAB), each comprising four 7-day treatments with a washout of ≥14 days between the second and third treatments. Treatment A = ASA + ER-DP 25 mg/200 mg (Aggrenox^®) twice daily (BID) alone; B = ASA + ER-DP 25 mg/200 mg BID + omeprazole (Prilosec^®) 80 mg once daily (QD) following ASA + ER-DP alone for 7 days; C = omeprazole 80 mg QD alone; D = omeprazole 80 mg QD + ASA + ER-DP 25 mg/200 mg BID following omeprazole alone for 7 days.

Main Outcome Measures

The main outcome measures were systemic PK exposure to ER-DP and ASA inhibition of arachidonic acid-induced platelet aggregation.

Results

Systemic exposure to ER-DP was similar with and without omeprazole, based on steady-state area under the concentration-time curve (AUC) from 0 to 12 h (AUC_0–12,ss, ng·h/mL) and maximum plasma concentration (C_max,ss, ng/mL). For the treatment comparison D versus A, the percent mean ratios were 96.38 (90 % confidence interval [CI] 90.96–102.13) for AUC_0–12,ss and 92.03 (86.95–97.40) for C_max,ss. The ER-DP concentration versus time profiles were nearly superimposable. There was no effect on the PDs of the ASA component: the extent of ASA inhibition of arachidonic acid-induced platelet aggregation was almost identical with and without omeprazole, with a percent mean ratio for treatment D versus A = 99.02 (90 % CI 98.32–99.72) at 4 h after last dose. All treatments were well tolerated.

Conclusion

The PK and PD behavior of ASA + ER-DP was not altered by concurrent administration of omeprazole.     

Effects of coincident 5-HT1A receptor stimulation and NMDA receptor antagonism on l-DOPA-induced dyskinesia and rotational behaviors in the hemi-parkinsonian rat

Rationale

Serotonin 1A receptor (5-HT1AR) agonists reduce l-DOPA-induced dyskinesia and enhance motor function in experimental and clinical investigations of Parkinson’s disease (PD). While the mechanism(s) by which these effects occur are unclear, recent research suggests that modulation of glutamate neurotransmission contributes.

Objective

To further delineate the relationship between 5-HT_1A receptors and glutamate, the current study examined the effects of the 5-HT_1AR agonist, ±8-OH-DPAT and the N-methyl-d-aspartic acid receptor (NMDAR) antagonist, MK-801, on l-DOPA-induced motor behavior.

Materials and methods

Unilateral 6-hydroxydopamine lesioned male Sprague–Dawley rats were rendered dyskinetic with 1 week of daily l-DOPA (12 mg/kg, i.p.) + benserazide (15 mg/kg, i.p.). On test days, one group of rats received pretreatments of: ±8-OH-DPAT (0, 0.03, 0.1, 0.3 mg/kg, i.p.) or MK-801 (0, 0.03, 0.1, 0.3 mg/kg, i.p.). A second group was administered combined ±8-OH-DPAT (0, 0.03 or 0.1 mg/kg, i.p.) + MK-801 (0, 0.1 mg/kg, i.p.). Pretreatments were followed by l-DOPA administration, after which, abnormal involuntary movements (AIMs) and rotations were monitored. To investigate effects on motor performance, subthreshold doses of ±8-OH-DPAT (0.03 mg/kg, i.p.) + MK-801 (0.1 mg/kg, i.p.) were administered to l-DOPA-naïve hemiparkinsonian rats before the forepaw adjusting steps test.

Results

Individually, both ±8-OH-DPAT and MK-801 dose-dependently decreased l-DOPA-induced AIMs without affecting rotations. Combined subthreshold doses of ±8-OH-DPAT+MK-801 reduced l-DOPA-induced AIMs and potently enhanced contralateral rotations without altering l-DOPA-induced motor improvements.

Conclusions

The current results indicate a functional interaction between 5-HT_1AR and NMDAR that may improve pharmacological treatment of PD patients.     

CRF1 receptor antagonists do not reverse pharmacological disruption of prepulse inhibition in rodents

Rationale

As enhanced corticotropin-releasing factor (CRF) transmission is associated with induction of sensorimotor gating deficits, CRF₁ receptor antagonists may reverse disrupted prepulse inhibition (PPI), an operational measure of sensorimotor gating.

Objectives

To determine the effects of CRF₁ receptor antagonists in pharmacological models of disrupted PPI and to determine if long-term elevated central CRF levels alter sensitivity towards PPI disrupting drugs.

Methods

CP154,526 (10–40 mg/kg), SSR125543 (3–30 mg/kg) and DMP695 (40 mg/kg) were tested on PPI disruption provoked by d-amphetamine (2.5, 3 mg/kg), ketamine (5, 30 mg/kg) and MK801 (0.2, 0.5 mg/kg) in Wistar rats, C57Bl/6J and CD1 mice, and on spontaneously low PPI in Iffa Credo rats and DBA/2J mice. PPI-disrupting effects of d-amphetamine (2.5–5 mg/kg) and MK801 (0.3–1 mg/kg) were examined in CRF-overexpressing (CRFtg) mice, which display PPI deficits. Finally, we determined the influence of CP154,526 on d-amphetamine-induced dopamine outflow in nucleus accumbens and prefrontal cortex of CRFtg mice using in vivo microdialysis.

Results

No CRF_1?antagonists improved PPI deficits in any test. CRFtg mice showed blunted PPI disruption in response to MK801, but not d-amphetamine. Further, d-amphetamine-induced dopamine release was less pronounced in CRFtg versus wild-type mice, a response normalized by pretreatment with CP154,526.

Conclusion

The inability of CRF₁ receptor antagonists to block pharmacological disruption of sensorimotor gating suggests that the involvement of CRF1 receptors in the modulation of dopaminergic and glutamatergic neurotransmission relevant for sensory gating is limited. Furthermore, the alterations observed in CRFtg mice support the notion that long-term elevated central CRF levels induce changes in these neurotransmitter systems.     

High Therapeutic Efficiency of Magnetic Hyperthermia in Xenograft Models Achieved with Moderate Temperature Dosages in the Tumor Area

Purpose

Tumor cells can be effectively inactivated by heating mediated by magnetic nanoparticles. However, optimized nanomaterials to supply thermal stress inside the tumor remain to be identified. The present study investigates the therapeutic effects of magnetic hyperthermia induced by superparamagnetic iron oxide nanoparticles on breast (MDA-MB-231) and pancreatic cancer (BxPC-3) xenografts in mice in vivo.

Methods

Superparamagnetic iron oxide nanoparticles, synthesized either via an aqueous (MF66; average core size 12 nm) or an organic route (OD15; average core size 15 nm) are analyzed in terms of their specific absorption rate (SAR), cell uptake and their effectivity in in vivo hyperthermia treatment.

Results

Exceptionally high SAR values ranging from 658?±?53 W*g_Fe ^?1 for OD15 up to 900?±?22 W*g_Fe ^?1 for MF66 were determined in an alternating magnetic field (AMF, H?=?15.4 kA*m^?1 (19 mT), f?=?435 kHz). Conversion of SAR values into system-independent intrinsic loss power (ILP, 6.4?±?0.5 nH*m²*kg^?1 (OD15) and 8.7?±?0.2 nH*m²*kg^?1 (MF66)) confirmed the markedly high heating potential compared to recently published data. Magnetic hyperthermia after intratumoral nanoparticle injection results in dramatically reduced tumor volume in both cancer models, although the applied temperature dosages measured as CEM43T90 (cumulative equivalent minutes at 43°C) are only between 1 and 24 min. Histological analysis of magnetic hyperthermia treated tumor tissue exhibit alterations in cell viability (apoptosis and necrosis) and show a decreased cell proliferation.

Conclusions

Concluding, the studied magnetic nanoparticles lead to extensive cell death in human tumor xenografts and are considered suitable platforms for future hyperthermic studies.     

Does a Hot Drink Provide Faster Absorption of Paracetamol Than a Tablet? A Pharmacoscintigraphic Study in Healthy Male Volunteers

Purpose

To investigate the hypothesis that paracetamol is absorbed faster from a hot drink than from a standard tablet using simultaneous scintigraphic imaging and pharmacokinetic sampling.

Methods

Twenty-five healthy male volunteers received both paracetamol formulations in a randomised manner. The formulation administered in the first treatment arm was radiolabelled to allow scintigraphic monitoring. In both treatment arms, blood samples were taken for assessing paracetamol absorption.

Results

Following the hot drink, paracetamol absorption was both significantly faster and greater over the first 60 min post-dose compared with the tablet, as evidenced by the median time to reach t_0.25?μg/mL of 4.6 and 23.1 min, respectively, and AUC_0-60 of 4668.00 and 1331.17 h*ng/mL, respectively. In addition, t_max was significantly shorter for the hot drink (median time = 1.50 h) compared with the tablet (1.99 h). However, C_max was significantly greater following the tablet (9,077 ng/mL) compared with the hot drink (8,062 ng/mL). Onset of gastric emptying after the hot drink was significantly faster than after the standard tablet (7.9 versus 54.2 min), as confirmed scintigraphically.

Conclusions

Compared with a standard tablet, a hot drink provides faster absorption of paracetamol potentially due to more rapid gastric emptying.     

Synthesis, anti-inflammatory, and structure antioxidant activity relationship of novel 4-quinazoline

The practice of medicinal chemistry is devoted to the discovery and development of new agents for treating disease. A new derivative of methyl 2-((E)-3-(3,4-dihydroxyphenyl)acrylamido)benzoate 2 was synthesized by reacting the amino group of methyl anthranilate 1 with caffeic acid in the presence of PCl₃. Cyclcondensation of 2 with hydrazine hydrate afforded the corresponding 2,3-dihydro-2-(3,4-dihydroxyphenyl) pyrazolo[5,1-b]quinazolin-9(1H)-one 3. The median lethal doses (LD_50s) of compounds 2 and 3 in mice were 1,135 and 495 mg/kg b.w., respectively. The anti-inflammatory, reducing power, chelating activity on Fe²⁺, free radical-scavenging, and total antioxidant activities were more pronounced in compound 2 compared to compound 3. On the other hand, antipyretic activity was more pronounced in compound 3 compared to compound 2. Antioxidant activity of compounds 2 and 3 increased with increased concentrations. Total antioxidant activity of compounds 2, 3 and both standards decreased in the order of α-tocopherol > compound 2 > trolox > BHA > BHT > compound 3. Administration of compounds 2 and 3 orally to the rats at dose of 50, 100, and 150 mg/kg b.w., for 10 days showed non-significant changes in serum level of GOT, GPT, ALP, γ-GT, and LDH as compared with the control group. In addition, oral administration of the compound 2 at a concentration of 100 and 150 mg/kg b.w. and compound 3 at a concentration of 150 mg/kg b.w. daily to normal rats for 10 days showed a significant increase in liver GSH, GPx, GR, and GST activities and significant decrease in TBARS level. But, administration of diclofenac sodium (30 mg/kg b.w.) orally to the rats daily for 10 days to rats showed significant increase in serum SGOT, SGPT, ALP, γ-GT, and LDH and significant decrease in liver GSH, GPx, GR, and GST activities. These findings suggest that compounds 2 and 3 exhibited good antioxidant and anti-inflammatory activity and also showed effects on liver enzymes.     

Characterization and Evaluation of Multi-Component Crystals of Hydrochlorothiazide

Purpose

The present work aims at improving the physicochemical properties of hydrochlorothiazide, a poorly water soluble antihypertensive drug by preparing its multi-component crystals with nicotinic acid (HCT-NA) and 2-picolinic acid (HCT-PIC).

Methods

The crystals prepared by solution crystallization were investigated by thermoanalytical techniques. The crystal structures of HCT-NA (1) and HCT-PIC (2) were determined by the single crystal X-ray diffraction and were assessed for their aqueous solubility, antihypertensive activity and acute toxicity in rats.

Results

Both 1 and 2 crystallized in the orthorhombic space group P2₁2₁2₁ and formation of salts were confirmed. The solubility profiles of 1 and 2 in basic media showed a maximum release of 2.5 mg/ml and 1.9 mg/ml, respectively, in comparison to the drug (0.82 mg/ml). The in-vivo antihypertensive activity of 1 in deoxycorticosterone acetate salt induced hypertensive rats showed 1.5 fold improvement. No increase in the signs of toxicity were revealed in rats during the acute toxicity studies even at doses of 2,000 mg/kg by body weight in comparison to the free drug. Histopathological findings supported the safety of these multi-component crystals.

Conclusions

The new solid phases exhibit potential to be explored for the oral drug delivery of HCT with improved solubility and therapeutic outcome.     

Determination of dopamine D2 receptor occupancy by lurasidone using positron emission tomography in healthy male subjects

Rationale

A positron emission tomography (PET) study of dopamine D₂ receptor occupancy was conducted to support a rational dose selection for clinical efficacy studies with lurasidone, an atypical antipsychotic that was approved for the treatment of schizophrenia by the FDA in late 2010.

Objectives

To determine the dopamine D₂ receptor occupancy of lurasidone in the ventral striatum, putamen and caudate nucleus, and to characterize the relationship between lurasidone serum concentration and D₂ receptor occupancy.

Methods

A single oral dose of lurasidone (10, 20, 40, 60, or 80 mg) was administered sequentially to healthy male subjects (n?=?4 in each cohort). Two PET scans were performed. For each scan, 20 mCi of [¹¹C]raclopride was administered intravenously as a bolus injection, followed immediately by 90 min of PET scan acquisitions.

Results

The D₂ receptor occupancy levels were 41–43 % for 10 mg, 51–55 % for 20 mg, 63–67 % for 40 mg, 77–84 % for 60 mg, and 73–79 % for 80 mg of lurasidone. The relationship between D₂ receptor occupancy and the mean serum lurasidone concentration during the PET scan (C _PET) was similar for the putamen, caudate nucleus, and ventral striatum regions. Mean D₂ receptor occupancy levels correlated well with average peak serum concentration of lurasidone.

Conclusions

In healthy volunteers, single doses of lurasidone 40–80 mg resulted in D₂ receptor occupancy levels of >60 %, a level of receptor occupancy previously associated with clinical response for atypical antipsychotics.     

Effects of mood stabilizers on marble-burying behavior in mice

Rationale

Obsessive–compulsive disorder (OCD) is characterized by recurrent unwanted thoughts (obsessions), usually accompanied by repetitive behaviors (compulsions) intended to alleviate anxiety. Marble-burying behavior is a pharmacological model for study of OCD.

Objectives

In the present study, we examined the effects of mood stabilizers on marble-burying behavior in mice, as well as the role of GABA receptors in this behavior.

Methods

The effects of treatment with valproate, carbamazepine, lithium carbonate, lamotrigine, muscimol and baclofen on marble-burying behavior in mice were evaluated.

Results

Valproate (10, 30 and 100 mg/kg, i.p.) and carbamazepine (30 and 100 mg/kg, p.o.) significantly reduced marble-burying behavior without affecting total locomotor activity in ICR mice. Lamotrigine (30 mg/kg, i.p.) also significantly reduced marble-burying behavior in ddY mice. On the other hand, lithium carbonate (10, 30 and 100 mg/kg, i.p.) reduced total locomotor activity without affecting marble-burying behavior in ddY mice. The selective GABA_A receptor agonist muscimol (1 mg/kg) significantly reduced marble-burying behavior without affecting total locomotor activity, whereas the selective GABA_B receptor agonist baclofen (3 mg/kg) reduced total locomotor activity without affecting marble-burying behavior. Moreover, the selective GABA_A receptor antagonist bicuculline (3 mg/kg) significantly counteracted the decrease in marble-burying induced by the administration of muscimol (1 mg/kg) and valproate (100 mg/kg).

Conclusions

These results suggest that GABAergic mechanism is involved in marble-burying behavior, and that valproate, carbamazepine and lamotrigine reduce marble-burying behavior. Moreover, valproate reduces marble-burying behavior via a GABA_A receptor-dependent mechanism.     

Preparation, Characterization, and Release of Amoxicillin from Electrospun Fibrous Wound Dressing Patches

Purpose

To produce electrospun polymeric fibrous wound dressing patches that can release the antibiotic drug amoxicillin in a controlled manner.

Methods

Poly(D,L-lactide-co-glycolide) acid (PLGA) fibrous dressings with entrapped amoxicillin were produced by electrospinning. The morphology and successful entrapment of amoxicillin in the PLGA fibrous dressings were validated by scanning electron microscopy (SEM) and Fourier Transform Infrared (FTIR) spectroscopy. The rate of drug release from the dressing patches was measured in various media for a period of 21 days using UV spectroscopy.

Results

PLGA fibres entrapping amoxicillin were collected for 300 s and then cut to form square patches with an average weight of 55 mg. Each dressing patch contained ~2 mg of amoxicillin. The mean fibre diameter was 2.2?±?0.4 μm. The drug release from the PLGA dressings was found to be different for each medium during the 21-day release period with the highest and lowest concentration of drug released observed when the dressings were immersed in simulated body fluid (SBF) and phosphate buffered saline (PBS), respectively.

Conclusions

The release profiles obtained in this study and the well-established biocompatibility of PLGA indicate that the fibre-based patches with entrapped amoxicillin fabricated in this work are very well suited for applications in wound healing and infection control.     

Serotonergic hallucinogens differentially modify gamma and high frequency oscillations in the rat nucleus accumbens

Rationale

The nucleus accumbens (NAc) is a site critical for the actions of many drugs of abuse. Psychoactive compounds, such as N-methyl-d-aspartate receptor (NMDAR) antagonists, modify gamma (40-90) and high frequency oscillations (HFO, 130–180 Hz) in local field potentials (LFPs) recorded in the NAc. Lysergic acid diethylamide (LSD) and 2,5-dimethoxy-4-iodoamphetamine (DOI) are serotonergic hallucinogens and activation of 5HT_2A receptors likely underlies their hallucinogenic effects. Whether these compounds can also modulate LFP oscillations in the NAc is unclear.

Objective

This study aims to examine the effect of serotonergic hallucinogens on gamma and HFO recorded in the NAc and to test whether 5HT_2A receptors mediate the effects observed.

Methods

LFPs were recorded from the NAc of freely moving rats. Drugs were administered intraperitoneally.

Results

LSD (0.03–0.3 mg/kg) and DOI (0.5–2.0 mg/kg) increased the power and reduced the frequency of HFO. In contrast, the hallucinogens produced a robust reduction in the power of low (40–60 Hz), but not high gamma oscillations (70–90 Hz). MDL 11939 (1.0 mg/kg), a 5HT_2A receptor antagonist, fully reversed the changes induced by DOI on HFO but only partially for the low gamma band. Equivalent increases in HFO power were observed after TCB-2 (5HT_2A receptor agonist, 0.1–1.5 mg/kg), but not CP 809101 (5H_2C receptor agonist, 0.1–3 mg/kg). Notably, hallucinogen-induced increases in HFO power were smaller than those produced by ketamine (25 mg/kg).

Conclusions

Serotonergic hallucinogen-induced changes in HFO and gamma are mediated, at least in part, by stimulation of 5HT_2A receptors. Comparison of the oscillatory changes produced by serotonergic hallucinogens and NMDAR antagonists are also discussed.     

CB1 antagonism: interference with affective properties of acute naloxone-precipitated morphine withdrawal in rats

Rationale

Modulation of the endocannabinoid system has been found to interfere with opiate withdrawal. The potential of activation and blockade of the endocannabinoid system to prevent the aversive-affective state of naloxone-precipitated morphine withdrawal (MWD) was investigated in a one-trial conditioned place aversion (CPA) paradigm.

Objective

CPA provides a sensitive measure of the motivational effects of acute MWD. The potential of the fatty acid amide hydrolase (FAAH) inhibitors, URB597 and PF-3845, the CB₁ antagonist/inverse agonist, AM251, and the neutral CB₁ antagonists, AM4113 and AM6527 (oral), to interfere with establishment of a MWD-induced CPA was investigated. As well, the potential of AM251 and AM4113 to interfere with reinstatement of a previously established MWD-induced CPA was investigated.

Materials and methods

Using a one-trial place conditioning paradigm, rats were administered naloxone (1 mg/kg, subcutaneous (sc)) 24 h after receiving a high dose of morphine (20 mg/kg, sc) and were placed on the conditioning floor. To determine the effect of each pretreatment drug on the establishment of the MWD-induced CPA, URB597 (0.3 mg/kg, intraperitoneally (ip)), PF-3845 (10 mg/kg, ip), AM251 (1 or 2.5 mg/kg, ip), AM4113 (1 or 2.5 mg/kg, ip), and AM6527 (5 mg/kg, oral) were administered prior to conditioning.

Results

AM251 (2.5, but not 1 mg/k), AM4113, and AM6527, but not URB597 or PF-3845, interfered with the establishment of the MWD-induced CPA. AM251 and AM4113 did not prevent reinstatement of the CPA.

Conclusions

Neutral antagonism of the CB₁ receptor reduces the aversive affective properties of morphine withdrawal.     

Role of gamma-aminobutyric acid type A (GABAA) receptor subtypes in acute benzodiazepine physical dependence-like effects: evidence from squirrel monkeys responding under a schedule of food presentation

Rationale

Assays of schedule-controlled responding can be used to characterize the pharmacology of benzodiazepines and other GABA_A receptor modulators, and are sensitive to changes in drug effects that are related to physical dependence.

Objective

The present study used this approach to investigate the role of GABA_A receptor subtypes in mediating dependence-like effects following benzodiazepine administration.

Methods

Squirrel monkeys (n?=?6) were trained on a fixed-ratio schedule of food reinforcement. Initially, the response rate-decreasing effects of chlordiazepoxide (0.1–10 mg/kg; nonselective GABA_A receptor agonist), zolpidem (0.032–1.0 mg/kg; α1 subunit-containing GABA_A subtype-preferring agonist), and HZ-166 (0.1–10 mg/kg; functionally selective α2 and α3 subunit-containing GABA_A receptor agonist) were assessed. Next, acute dependence-like effects following single injections of chlordiazepoxide, zolpidem, and HZ-166 were assessed with flumazenil (0.1–3.2 mg/kg; nonselective GABA_A receptor antagonist). Finally, acute dependence-like effects following zolpidem administration were assessed with βCCt and 3-PBC (0.1–3.2 mg/kg and 0.32–10 mg/kg, respectively; α1 subunit-containing GABA_A receptor antagonists).

Results

Chlordiazepoxide, zolpidem, and HZ-166 produced dose- and time-dependent decreases in response rates, whereas flumazenil, βCCT, and 3-PBC were ineffective. After the drug effects waned, flumazenil produced dose-dependent decreases in response rates following administration of 10 mg/kg chlordiazepoxide and 1.0 mg/kg zolpidem, but not following any dose of HZ-166. Further, both βCCT and 3-PBC produced dose-dependent decreases in response rates when administered after 1.0 mg/kg zolpidem.

Conclusions

These data raise the possibility that α1 subunit-containing GABA_A receptors play a major role in physical dependence-related behaviors following a single injection of a benzodiazepine.     

The effects of BMY-14802 against l-DOPA- and dopamine agonist-induced dyskinesia in the hemiparkinsonian rat

Rationale

l-DOPA continues to be the primary treatment for patients with Parkinson’s disease; however, the benefits of long-term treatment are often accompanied by debilitating side effects known as dyskinesias. In recent years, several 5-HT_1A receptor agonists have been found to reduce dyskinesia in clinical and experimental models of PD. The purported sigma-1 antagonist, BMY-14802 has been previously demonstrated to reduce l-DOPA induced dyskinesia in a 5-HT_1A receptor dependent manner.

Objective

In the present study, we extend these findings by examining the anti-dyskinetic potential of BMY-14802 against l-DOPA, the D₁ receptor agonist SKF81297 and the D₂ receptor agonist, quinpirole, in the hemi-parkinsonian rat model. In addition, the receptor specificity of BMY-14802’s effects was evaluated using WAY-100635, a 5-HT_1A receptor antagonist.

Results

Results confirmed the dose-dependent (20?>?10?>?5 mg/kg) anti-dyskinetic effects of BMY-14802 against l-DOPA with preservation of anti-parkinsonian efficacy at 10 mg/kg. BMY-14802 at 10 and 20 mg/kg also reduced dyskinesia induced by both D₁ and D₂ receptor agonists. Additionally, BMY-14802’s anti-dyskinetic effects against l-DOPA, but not SKF81297 or quinpirole, were reversed by WAY-100635 (0.5 mg/kg).

Conclusion

Collectively, these findings demonstrate that BMY-14802 provides anti-dyskinetic relief against l-DOPA and direct DA agonist in a preclinical model of PD, acting via multiple receptor systems and supports the utility of such compounds for the improved treatment of PD.     

The CRF1 receptor antagonist SSR125543 prevents stress-induced cognitive deficit associated with hippocampal dysfunction: Comparison with paroxetine and d-cycloserine

Rationale

The selective CRF₁ (corticotropin releasing factor type 1) receptor antagonist SSR125543 has been previously shown to attenuate the long-term cognitive deficit produced by traumatic stress exposure. Memory disturbances described in post-traumatic stress disorder (PTSD) patients are believed to be associated with changes in neuronal activity, in particular at the level of the hippocampus.

Objectives

The present study aims at investigating whether the effects of SSR125543 (10 mg/kg/day for 2 weeks) on cognitive impairment induced by traumatic stress exposure are associated with changes in hippocampal excitability. Effects of SSR125543 were compared to those of the 5-HT reuptake inhibitor, paroxetine (10 mg/kg/day), and the partial N-methyl-d-aspartate (NMDA) receptor agonist, d-cycloserine (10 mg/kg/day), two compounds which have demonstrated clinical efficacy against PTSD.

Methods

Mice received two unavoidable electric foot-shocks. Then, 1 or 16 days after stress, they were tested for their memory performance using the object recognition test. Neuronal excitability was recorded during the third week post-stress in the CA1 area of the hippocampus. Drugs were administered from day 1 post-stress to the day preceding the electrophysiological study.

Results

Application of electric shocks produced cognitive impairment 16, but not 1 day after stress, an effect which was associated with a decrease in hippocampal neuronal excitability. Both stress-induced effects were prevented by repeated administration of SSR125543, paroxetine and d-cycloserine.

Conclusions

These findings confirm that the CRF₁ receptor antagonist SSR125543 is able to attenuate the behavioral effects of traumatic stress exposure and indicate that these effects are associated with a normalization of hippocampal neuronal excitability impaired by stress.     

Yohimbine increases opioid-seeking behavior in heroin-dependent, buprenorphine-maintained individuals

Rationale

In laboratory animals, the biological stressor yohimbine (α₂-noradrenergic autoreceptor antagonist) promotes drug seeking. Human laboratory studies have demonstrated that psychological stressors can increase drug craving but not that stressors alter drug seeking.

Objectives

This clinical study tested whether yohimbine increases opioid-seeking behavior.

Methods

Ten heroin-dependent, buprenorphine-stabilized (8 mg/day) volunteers sampled two doses of hydromorphone [12 and 24 mg IM in counterbalanced order, labeled drug A (session 1) and drug B (session 2)]. During each of six later sessions (within-subject, double-blind, randomized crossover design), volunteers could respond on a 12-trial choice progressive ratio task to earn units (1 or 2 mg) of the sampled hydromorphone dose (drug A or B) vs money ($2) following different oral yohimbine pretreatment doses (0, 16.2, and 32.4 mg).

Results

Behavioral economic demand intensity and peak responding (O _max) were significantly higher for hydromorphone 2 than 1 mg. Relative to placebo, yohimbine significantly increased hydromorphone demand inelasticity, more so for hydromorphone 1-mg units (P _max?=?909, 3,647, and 3,225 for placebo, 16.2, and 32.4 mg yohimbine doses, respectively) than hydromorphone 2-mg units (P _max?=?2,656, 3,193, and 3,615, respectively). Yohimbine produced significant but clinically modest dose-dependent increases in blood pressure (systolic?≈?15 and diastolic?≈?10 mmHg) and opioid withdrawal symptoms, and decreased opioid agonist symptoms and elated mood.

Conclusions

These findings concur with preclinical data by demonstrating that yohimbine increases drug seeking; in this study, these effects occurred without clinically significant subjective distress or elevated craving, and partly depended on opioid unit dose.     

Synthesis and anticonvulsant activity of novel quinazolin-4(3H)-one derived pyrazole analogs

Eighteen novel 6,8-(dibromo/unsubstituted)-2-(methyl/phenyl)-3-(4-(5-(substitutedphenyl)-3-phenyl-4,5-dihydro-1H-pyrazole-1-carbonyl)phenyl)-quinazolin-4(3H)-ones 4a–4r were designed and synthesized in good yield. Antiepileptic screening of the title compounds was performed using MES and scPTZ seizures tests while the neurotoxicity was determined by rotorod test. In the preliminary screening, compounds 4d, 4e, 4p, 4q, and 4r were found active in MES model, while 4a, 4d, 4f, 4m, and 4p showed significant antiepileptic activity in scPTZ model. Further, all these eight compounds were administered to rats and compounds 4e, 4p, and 4q showed better activity than Phenytoin in oral route. Among these compounds 4p revealed protection in MES after i.p. administration at a dose of 30 mg/kg (0.5 h) and 100 mg/kg (4 h). The compound 4p also provided protection in the scPTZ at a dose of 100 mg/kg (0.5 h) and 300 mg/kg (4 h).     

Antiangiogenic Effect of Docetaxel and Everolimus as Individual and Dual-Drug-Loaded Micellar Nanocarriers

Purpose

The in vitro inhibitory effect of Docetaxel (DTX) and Everolimus (EVR) alone and together in poly(ethylene glycol)-block-poly(D,L-lactic acid) (PEG-b-PLA) nanocarriers on angiogenic processes and acute toxicity in mice was evaluated.

Methods

PEG-b-PLA DTX and/or EVR nanocarriers were characterized for size, drug loading, stability, and drug release. Cell proliferation, tubule formation, and migration studies were performed in Human Umbilical Vein Endothelial Cells (HUVEC) and Maximum Tolerated Doses (MTD) studies were in mice.

Results

DTX and EVR loading was 1.93 and 2.00 mg/mL respectively with similar solubilities for dual-drug micelles. All micelles were below 30 nm with diffusion controlled drug release. The IC₅₀ for DTX, EVR micelles were, 6.80?±?0.67, 18.57?±?2.86 and 0.65?±?0.11 nM respectively with a synergistic inhibitory effect for dual-drug nanocarriers. Significant inhibition of tube formation occurred upon treatment with dual-drug nanocarriers as compared to individual micelles. EVR presence in dual-drug nanocarriers was able to significantly increase the inhibition of the migration of HUVEC by DTX. The MTDs for EVR, DTX and dual-drug micelles were 50, 30 and 20 mg/kg for each respectively.

Conclusions

DTX-EVR dual-drug nanocarriers have antiangiogenic effects in vitro mediated through cellular angiogenic process and possess clinically relevant MTD.