Modulation of alcohol consumption using an operant self-administration paradigm: effects of a new dopamine aminoacidic conjugate, Phenylalanine-β(3,4dihydroxyphenyl)-etilamide.

Rewarding and reinforcing properties of alcohol have been shown to be mediated by activation of the mesolimbic dopaminergic system. Experimental evidences suggest that mesolimbic dopamine system is hypofunctional in addicted brain; further, reduced dopaminergic activity outlasts somatic signs of withdrawal and may drive craving and relapse. Boosting strategy on dopaminergic neurons could represent a valid therapy. Effects of pharmacological manipulation of brain Dopaminergic receptors by a new dopamine conjugate, Phenylalanine-β(3,4dihydroxyphenyl)-etilamide (DA-Phen), on operant behaviour and on both acute and prolonged withdrawal symptoms during ethanol abstinence have been evaluated. Mal…

New prospective in treatment of Parkinson's disease: Studies on permeation of ropinirole through buccal mucosa

The aptitude of ropinirole to permeate the buccal tissue was tested using porcine mucosa mounted on Franz-type diffusion cells as ex vivo model. Drug permeation was also evaluated in presence of various penetration enhancers and in iontophoretic conditions. Ropinirole, widely used in treatment of motor fluctuations of Parkinson's disease, passes the buccal mucosa. Flux and permeability coefficient values suggested that the membrane does not appear a limiting step to the drug absorption. Nevertheless, an initial lag time is observed but the input rate can be modulated by permeation enhancement using limonene or by application of electric fields. Absorption improvement was accompanied by the …

Aminoacidic derivatives as novel CNS-targeted neurotherapeutics

Drug delivery to the CNS is subject to the permeability limitations imposed by the BBB that regulates movements of actives in and out of the brain. During the drug discovery phase a key aspect could be the selection of the compounds properties crucial for brain penetration. Novel CNS-targeted neurotherapeutics should possess the optimal characteristics that allow passive diffusion through the BBB via the transcellular route, or have the structural features necessary to serve as a substrate for one of the endogenous transport systems of the BBB. An attractive and rewarding chemistry-based strategy, employed to increase the CNS transport of poorly penetrating therapeutic agents, is the transi…

Physical Methods for Enhancing Oral Mucosal Delivery: Sonophoresis, Iontophoresis and Electroporation

The need for more rapid onset of action and improved absorption of medications has resulted in great development of drug delivery technologies. Transmucosal drug delivery offers a convenient route of administration for a variety of clinical indications. Unfortunately, the wide variability in structure of the oral mucosal tissues could constitute a key factor in drug penetration and absorption. To circumvent this obstacle and to increase the drug flux through the mucosal membranes, different approaches to permeation enhancement are used. This chapter describes the most significant aspects of the physical techniques widely used such as sonophoresis, iontophoresis, and electroporation. These p…

A new dopamine amino-acid conjugate: preclinical in vitro studies and evaluation of behavioural effects in rats

It is well established that alterations in the functionality of dopaminergic transmission are associated with neurodegenerative diseases such as Parkinson’s Disease. The purpose of this study was to investigate the activity of a new dopamine amino-acid conjugate: L-phenylalanine-β-(3,4-dihydroxyphenyl) etilamide(DA-Phe) in the central nervous system, by assessing its influence on different behavioural parameters in the rat. Preliminarily, we tested the in vitro stability in plasmatic environment following the disappearance of DA-Phen from human plasma and the concurrent appearance of dopamine. Using rat brain homogenate, we also evaluated the level of DA-Phen cleavage by cerebral enzymes an…

DA-Phen as a new potential DA-mimetic agent for treatment of alcohol addiction: preclinical in vivo studies

Rewarding and reinforcing properties of alcohol are mediated by activation of the mesolimbic dopaminergic system1. This neurosystem is hypofunctional in the addicted brain, even beyond somatic and psychological signs of withdrawal. Boosting strategy on the dopaminergic tone could represent a valid approach to alcohol addiction treatment2. The effects of a new dopamine conjugate3 (2-amino-N-[2-(3,4-dihydroxy-phenyl)-ethyl]-3-phenyl-propionamide, DA-Phen) on operant behaviour and on withdrawal behaviour, following alcohol deprivation, were evaluated. The concentration of acetaldehyde (ACD), ethanol's first metabolite, as an indirect measure of the possible DA-Phen modulation in alcohol consum…

Evaluation of neuropeptide Y expression during acetaldehyde withdrawal in rats. Focus on hippocampus and nucleus accumbens

Stress-related neuropeptides are involved in setting up alcohol addiction. Ethanol is able to acutely induce CRH and ACTH release, while cronically a dampered response of the hypothalamus -pituitary- adrenal (HPA) axis has been observed. Also neuropeptide Y (NPY) has been shown to modulate ethanol consumption, and its central expression seems inversely correlated to ethanol intake. Recent in vivo and in vitro evidence have highlighted the key role of acetaldehyde (ACD), ethanol first metabolite, as a mediator of the central effects of ethanol, even as modulator of the neuropeptidergic transmission in the rat brain. The aim of this study was to investigate NPY immunoreactivity following a 4-…

Development and Characterization of an Amorphous Solid Dispersion of Furosemide in the Form of a Sublingual Bioadhesive Film to Enhance Bioavailability.

Administered by an oral route, Furosemide (FUR), a diuretic used in several edematous states and hypertension, presents bioavailability problems, reported as a consequence of an erratic gastrointestinal absorption due to various existing polymorphic forms and low and pH-dependent solubility. A mucoadhesive sublingual fast-dissolving FUR based film has been developed and evaluated in order to optimize the bioavailability of FUR by increasing solubility and guaranteeing a good dissolution reproducibility. The Differential Scanning Calorimetry (DSC) analyses confirmed that the film prepared using the solvent casting method entrapped FUR in the amorphous state. As a solid dispersion, FUR increa…

Design, synthesis and preliminary evaluation of dopamine-amino acid conjugates as potential D1 dopaminergic modulators.

Abstract The dopamine-amino acid conjugate DA-Phen was firstly designed to obtain a useful prodrug for the therapy of Parkinson's disease, but experimental evidence shows that it effectively interacts with D1 dopamine receptors (D1DRs), leading to an enhancement in cognitive flexibility and to the development of adaptive strategies in aversive mazes, together with a decrease in despair-like behavior. In this paper, homology modelling, molecular dynamics, and site mapping of D1 receptor were carried out with the aim of further performing docking studies on other dopamine conjugates compared with D1 agonists, in the attempt to identify new compounds with potential dopaminergic activity. Two n…

Effects of DA-Phen, a dopamine-aminoacidic conjugate, on alcohol intake and forced abstinence

The mesolimbic dopamine (DA) system plays a key role in drug reinforcement and is involved in the development of alcohol addiction. Manipulation of the DAergic system represents a promising strategy to control drug-seeking behavior. Previous studies on 2-amino-N-[2-(3,4-dihydroxy-phenyl)-ethyl]-3-phenyl-propionamide (DA-Phen) showed in vivo effects as a DA-ergic modulator. This study was aimed at investigate DA-Phen effects on operant behavior for alcohol seeking behavior, during reinstatement following subsequent periods of alcohol deprivation. For this purpose, male Wistar rats were tested in an operant paradigm of self-administration; behavioral reactivity and anxiety like-behavior durin…

Buccal delivery as a new challenge for treatment of motor fluctuations in Parkinson's Disease

A NEW DOPAMINE-AMINOACID CONJUGATE: SYNTHESIS AND DETERMINATION OF PHYSICO-CHEMICAL PROPERTIES USEFUL TO CROSS THE BBB

Nuovi derivati della Dopamina nell’Addiction da sostanze d’abuso: studi preclinici su modelli sperimentali murini

DA-Phen, a new dopamine aminoacid conjugate: in vivo testing and molecular modeling as dopaminergic modulator

Comparative Study of the Effects Exerted by N-Valproyl-L-Phenylalanine and N-valproyl-L-tryptophan on CA1 Hippocampal Epileptiform Activity in Rat

Background: The research on the improvement of epilepsy therapy is constantly growing. Valproyl-LPhenylalanine (VPA-Phen) and N-valproyl-L-tryptophan (VPA-Tryp) were synthesized to increase the antiepileptic efficacy of valproic acid. Methods: VPA-Phen and VPA-Tryp were comparatively tested on CA1 hippocampal epileptiform bursting activity obtained by increasing potassium and lowering calcium and magnesium concentrations in the fluid perfusing rat brain slices. Each slice was treated with a single concentration (0.2, 0.5, 1 mM) of VPA-Phen or VPA-Tryp. Both burst duration and interburst frequency, during and after treatment, were off-line compared with baseline values. For both parameters,…

Acetaldehyde operant self-administration in rats: focus on D2-receptor activation.

Acetaldehyde (ACD), ethanol first metabolite, is rewarding in rodents and humans; it induces “place preference”, is self-administer directly in the VTA, orally in an operant/conflict paradigm and increases DA neurons’ firing. This research aims at investigating DA2-receptor role in the reinstatement of acetaldehyde operant-drinking behaviour, following induction, maintenance and abstinence in the rat. Male Wistar rats are trained to orally self-administer ACD solution (3.2% v/v) or water, in an operant chamber under a FR1. Afterwards animals undergo cyclic periods of deprivation and relapse to ACD. The effect ofD2-receptor activation by quinpirole (0.03mg/kg,i.p.) on operant ACD self-admini…

Is Acetaldehyde a substance of abuse? Evidence from a free-access, three-bottle choice paradigm

At present, neuroscience literature dealing with Acetaldehyde (ACD), ethanol first metabolite, as a drug of abuse, reported conditioned taste aversion paradigm and conditioned place preference, following ICV or i.p. administration. No reports exist on ACD oral self-administration probably because of its high volatility. For this reason, this pilot study was aimed at the evaluation of ACD concentration in aqueous solutions, and consequently to the rat drinking behaviour when acetaldehyde was presented in a free-access paradigm together with water and a sweet solution. Preliminarly we investigated the loss of ACD content in aqueous standard solutions. For the investigation of ACD concentratio…

Assessment of in vivo organ-uptake and in silico prediction of CYP mediated metabolism of DA-Phen, a new dopaminergic agent

Abstract The drug development process strives to predict metabolic fate of a drug candidate, together with its uptake in major organs, whether they act as target, deposit or metabolism sites, to the aim of establish a relationship between the pharmacodynamics and the pharmacokinetics and highlight the potential toxicity of the drug candidate. The present study was aimed at evaluating the in vivo uptake of 2-Amino-N-[2-(3,4-dihydroxy-phenyl)-ethyl]-3-phenyl-propionamide (DA-Phen) − a new dopaminergic neurotransmission modulator, in target and non-target organs of animal subjects and integrating these data with SMARTCyp results, an in silico method that predicts the sites of cytochrome P450-m…

In situ delivery of corticosteroids for treatment of oral diseases.

In many mucocutaneous disorders, corticosteroids therapy is currently central. Systemic therapy is restricted to severe disorders whereas topical applications are considered as the first-line treatment. The oral cavity environment, the medication form and other factors related to the delivery method are key factors for the therapy efficiency and effectiveness. Current marketed medications are not able to avoid wrong drug exposure and scarce patients’ compliance. Innovative in situ delivery systems are able to prolong the drug retention time on the mucosa and to avoid the drawbacks of conventional formulations. This review is intended to give a general overview of oral mucocutaneous patholo…

Physical methods to promote drug delivery on mucosal tissues of the oral cavity.

Introduction: The successful of drug delivery through the mucosal tissue of the oral cavity represents a current challenge as well as a great future perspective. The need for more rapid onset of action and improved absorption of medications has resulted in great development of drug delivery technologies that use physical methods to overcome the barrier properties of oral mucosae. Areas covered: This review discusses the various physical techniques which have been, and are being, explored to sustain drug delivery in the oral cavity. In particular, supersaturation, eutectic formation, iontophoresis, electroporation, sonophoresis, laser radiation, photomechanical waves, and needleless injectio…

Small endogenous molecules as moiety to improve targeting of CNS drugs.

A major challenge in the development of novel neuro-therapeutic agents is to effectively overcome the blood-brain barrier (BBB), which acts as a 'working dynamic barrier'. The core problem in the treatment of neurodegenerative diseases is failed delivery of potential medicines due to their inadequate permeation rate. Areas covered: The present review gives a summary of endogenous moieties used in synthesizing prodrugs, derivatives and bioisosteric drugs appositely designed to structurally resemble physiological molecular entities able to be passively absorbed or carried by specific carrier proteins expressed at BBB level. In particular, this overview focuses on aminoacidic, glycosyl, purine…

Studies on a new potential dopaminergic agent: in vitro BBB permeability, in vivo behavioural effects and molecular docking evaluation.

2-Amino-N-[2-(3,4-dihydroxy-phenyl)-ethyl]-3-phenyl-propionamide (DA-PHEN) has been previously synthesized to obtain a potential prodrug capable of release dopamine (DA) into CNS. However, DA-PHEN could act per se as a dopaminergic drug. In this study, the permeability transport (Pe), obtained by parallel artificial permeability assay (PAMPA), indicated a low passive transcellular transport (Pe = 0.32 ± 0.01 × 10(-6 )cm/s). Using the Caco-2 cell system, the Papp AP-BL in absorptive direction (3.36 ± 0.02 × 10(-5 )cm/s) was significantly higher than the Papp BL-AP in secretive direction (1.75 ± 0.07 × 10(-5 )cm/s), suggesting a polarized transport. The efflux ratio (Papp AP-BL/Papp BL-AP = 0…

N-Valproyl-L-Phenylalanine as new potential antiepileptic drug: Synthesis, characterization and in vitro studies on stability, toxicity and anticonvulsant efficacy

Valproic acid (VPA) is considered first-line drug in treatment of generalized idiopathic seizures such as absence, generalized tonic-clonic and myoclonic seizures. Among major antiepileptic drugs, VPA is also considered effective in childhood epilepsies and infantile spasms. Due to its broad activity, VPA acts as a mood stabilizer in bipolar disorder and it is useful in migraine prophylaxis. Despite its long-standing usage, severe reactions to VPA, such as liver toxicity and teratogenicity, are reported. To circumvent side effects due to structural characteristics of VPA, we synthesized in good yield a new VPA-aminoacid conjugate, the N-valproyl-L-Phenylalanine, and characterized by FT-IR, …

Acetaldehyde self-administration by a two-bottle choice paradigm: Consequences on emotional reactivity, spatial learning, and memory

Abstract Acetaldehyde, the first alcohol metabolite, is responsible for many pharmacological effects that are not clearly distinguishable from those exerted by its parent compound. It alters motor performance, induces reinforced learning and motivated behavior, and produces different reactions according to the route of administration and the relative accumulation in the brain or in the periphery. The effective activity of oral acetaldehyde represents an unresolved field of inquiry that deserves further investigation. Thus, this study explores the acquisition and maintenance of acetaldehyde drinking behavior in adult male rats, employing a two-bottle choice paradigm for water and acetaldehyd…

DESIGN AND CHARACTERIZATION OF MUCOADHESIVE SUBLINGUAL FILMS CONTAINING FUROSEMIDE

Buccal drug delivery: what's new and what does the future hold?

The buccal mucosa is the stratified squamous epithelial tissue inside lining of the cheeks. It is a favorable site of drug absorption since the tissue is non-keratinized, relatively immobile and strongly supplied with blood by a dense capillary-vessel network; moreover, it is highly tolerant to allergens, resistant to potentially harmful agents and has a relatively low enzymatic activity. The tissue consents quick onset of effect, offers an easily accessible and generally well-accepted site for drug delivery, is a useful route of administration in patients in an unconscious state (e.g., when swallowing is impaired), and is suitable for retentive dosage forms of administration. Buccal mucosa…

Aloin delivery on buccal mucosa: ex vivo studies and design of a new locoregional dosing system

Context: Chemoprevention of potential malignant disorders or cancerous lesions that affect oral mucosae requires extended duration of treatment. Locoregional delivery of natural products could represent a promising strategy for this purpose. Objective: To investigate the aptitude of aloin to permeate through, or accumulate in, the buccal mucosa and to develop a new prolonged oro-mucosal drug delivery system. Materials and Methods: Permeation/accumulation of aloin from Curacao Aloe (containing 50% barbaloin) was evaluated ex vivo, using porcine buccal mucosa as the most useful model to simulate human epithelium. Oro-mucosal matrix tablets were prepared by dispersing aloin (10% w/w) in Eudrag…

Optimization of local delivery of antifungal agents in the oral cavity by a new formulation

In recent years, with the increased use of antibiotics and immunosuppres-sive agents, there was an increased incidence of oral mycosis and Candida albicans is the most common etiologic agent in oropharyngeal candidiasis, especially in patients with HIV. The aim of this work is to develop a new dosage form containing miconazole (MN) to be topically applied on oral mucosa, allowing for a massive penetration of the drug in the tissue. The vehicle for the drug delivery was lipid microparticles incorporated in a hydrophilic gel. The lipospheres were obtained by hot melt encapsulation method using as matrix ingredients a mixtures of esters of fatty acids with higher fatty alcohols, having low mel…

Transbuccal delivery of l-dopa methyl ester: ex vivo permeation studies