Rapid, sensitive procedure to determine buspirone levels in rat brains using gas chromatography with nitrogen-phosphorus detection

Buspirone Nanovesicular Nasal System for Non-Hormonal Hot Flushes Treatment

The aim of this work was to design and characterize a new nanovesicular nasal delivery system (NDS) containing buspirone, and investigate its efficiency in an animal model for the treatment of hot flushes. The presence of multilamellar vesicles with a mean size distribution of 370 nm was evidenced by transition electron microscopy (TEM), cryo-scanning electron microscopy (Cryo-SEM), and dynamic light scattering (DLS) tests. Pharmacodynamic evaluation of the nasal treatment efficacy with the new system was carried out in ovariectomized (OVX) rat—an animal model for hot flushes—and compared with other treatments. We found that the nasal administration of a buspirone NDS resulted in a significant reduction in tail skin temperature (TST). This effect was not observed in the control buspirone-treated groups. Buspirone levels in the plasma and brain of nasally-treated normal rats were quantified and compared with those of rats that had received oral administration by a LC-MS/MS assay. A significantly higher bioavailability was achieved with the new treatment relative to an oral administration of the same drug dose. No pathological changes in the nasal cavity were observed following sub-chronic nasal administration of buspirone NDS. In conclusion, the data of our investigation show that buspirone in the new nanovesicular nasal carrier could be considered for further studies for the development of a treatment for the hot flushes ailment.

Mass spectrometric investigation of buspirone drug in comparison with thermal analyses and MO-calculations

The buspirone drug is usually present as hydrochloride form of general formula C(21)H(31)N(5)O(2).HCl, and of molecular weight (MW)=421.96. It is an analgesic anxiolytic drug, which does not cause sedative or depression of central nervous system. In the present work it is investigated using electron impact mass spectral (EI-MS) fragmentation at 70 eV, in comparison with thermal analyses (TA) measurements (TG/DTG and DTA) and molecular orbital calculation (MOC). Semi-empirical MO calculation, PM3 procedure, has been carried out on buspirone both as neutral molecule (in TA) and the corresponding positively charged species (in MS). The calculated MOC parameters include bond length, bond order, particle charge distribution on different atoms and heats of formation. The fragmentation pathways of buspirone in EI-MS lead to the formation of important primary and secondary fragment ions. The mechanism of formation of some important daughter ions can be illuminated from comparing with that obtained using electrospray ESIMS/MS mode mass spectrometer through the accurate mass measurement determination. The losses of the intermediate aliphatic part (CH2)4 due to cleavage of N-C bond from both sides is the primary cleavage in both techniques (MS and TA). The PM3 provides a base for fine distinction among sites of initial bond cleavage and subsequent fragmentation of drug molecule in both TA and MS techniques; consequently the choice of the correct pathway of such fragmentation knowing this structural session of bonds can be used to decide the active sites of this drug responsible for its chemical, biological and medical reactivity.

Flow injection analysis with tubular membrane ion-selective electrode and coated wires for buspirone hydrochloride

New Plastic membrane ion-selective electrode for buspirone hydrochloride based on buspironium tetraphenylborate was prepared. The electrode exhibited mean slope of calibration graph of 58.4 mV per decade of BusCl concentration at 25 degrees C. The electrode can be used within the concentration range 6.3 x 10(-5) - 10(-2) M BusCl at a pH range of 2.5-7.0. The standard electrode potentials were determined at different temperatures and used to calculate the isothermal temperature coefficient of the electrode, amounting to 0.00056 V degrees C(-1). The electrode showed a very good selectivity for BusCl with respect to a number of inorganic cations, sugars and amino acids. The electrode was applied to the potentiometric determination of the buspirone ion and its pharmaceutical preparation under batch and flow injection conditions. Also, buspirone was determined by conductimetric titrations. Graphite rod, copper and silver coated wire electrodes were prepared and characterized as sensors for the drug under investigation.

Common effects of chronically administered antipanic drugs on brainstem GABA(A) receptor subunit gene expression

Panic disorder is an anxiety disorder that can be treated by long-term administration of tricyclic antidepressants such as imipramine, monoamine oxidase inhibitors such as phenelzine, or the selective serotonin reuptake inhibitor (SSRI) antidepressants. Clinical data also indicate that some benzodiazepines, such as alprazolam, are effective antipanic agents, and that their therapeutic onset is faster than that of antidepressants. Benzodiazepines are well known for their action at GABA(A) receptors, and preclinical data indicate that imipramine and phenelzine also interfere with the GABAergic system. In addition some clinical data lend support to decreased benzodiazepine-sensitive receptor function in panic disorder patients. Using imipramine, phenelzine and alprazolam, we investigated, in rats, the possibility that the therapeutic efficacy of antipanic agents stems from the remodeling of GABAergic transmission in the pons-medulla region. Of the 12 GABA(A) receptor subunit (alpha 1--6, beta 1--3, gamma 1--3) steady-state mRNA levels investigated, we observed an increase in the levels of the alpha 3-, beta 1- and gamma 2-subunit transcripts with all three antipanic agents tested. The effects of imipramine and phenelzine on these subunits occurred after 21 days of treatment, while alprazolam effects were observed after 3 days of administration. Histochemical data suggest that the alpha 3 beta 1 gamma 2 subunits comprise a receptor subtype in the pons-medulla region. Therefore, we conclude that these molecular events parallel the therapeutic profile of the drugs examined. We further propose that these events may correspond to a remodeling of the GABA(A) receptor population, and may be useful markers for investigation of the antipanic properties of drugs.

Equine metabolism of buspirone studied by high-performance liquid chromatography/mass spectrometry

The metabolism and urinary excretion of a 100 mg dose of the non-sedating anxiolytic drug buspirone was examined using high-performance liquid chromatography/electrospray ionization mass spectrometry in the positive ion mode. In addition to a significant proportion of unchanged buspirone we were able to detect three major metabolite classes. These were identified as monohydroxy, dihydroxy and dihydroxymethoxy products. Detection of the metabolites and the parent drug was possible in all the urine samples collected (1-12 h) post-administration.