Cecilia Rustichelli

Solid-state study of polymorphic drugs : carbamazepine

Polymorphs of a compound have solid crystalline phases with different internal crystal lattices; in pharmaceuticals, differences due to polymorphism and pseudopolymorphism can affect bioavailability and effective clinical use. The aim of this work was to obtain the different polymorphic modifications of the anticonvulsant drug, carbamazepine, and to characterise them by means of typical structure-sensitive analytical techniques, such as FT-IR spectroscopy, XRPD and DSC. Further investigations were also performed by Hot Stage FT-IR thermomicroscopy, which permitted the visible and spectroscopic characterisation of the polymorphic forms during heating. Our results confirm the existence of three different polymorphic forms for anhydrous carbamazepine: Form III, the commercial one, Form I, obtained by heating Form III and Form II, crystallised from ethanolic solution. Substantial differences were detected among the polymorphs with regard to solid-state properties. Moreover, Hot Stage FT-IR thermomicroscopy proved its analytical potential to characterise the drugs polymorphism.

Study of flavonoids/β-cyclodextrins inclusion complexes by NMR, FT-IR, DSC, X-ray investigation☆

Flavonoids are natural substances with a lot of biological activities, including the antioxidant one. Their use in pharmaceutical field is, however, limited by their aqueous insolubility. As the formation of the inclusion complexes can improve their solubility in water, the flavonoids hesperetin, hesperidin, naringenin and naringin have been complexed with beta-cyclodextrin (beta-CD) by the coprecipitation method and studied in solution and in solid state by NMR, FT-IR, differential scanning calorimetry and X-ray techniques. The effects of complexation on the chemical shifts of the internal and external protons of beta-CD in the presence of each flavonoid were observed.

Study of β-blockers/β-cyclodextrins inclusion complex by NMR, DSC, X-ray and SEM investigation ☆

Abstract The formation of inclusion complexes between β-cyclodextrin with the two β-blockers, atenolol and celiprolol, have been studied in the aqueous environment and in the solid state by nuclear magnetic resonance (NMR) spectroscopy, X-ray, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) techniques. The magnitude of the chemical shifts of the interior and exterior β-cyclodextrin protons in the presence of each β-blocker indicated that these are included within the β-cyclodextrin cavity. In aqueous solution they form 1:1 complexes. In the solid state the formation of the β-cyclodextrin/atenolol (celiprolol) complexes is confirmed by X-ray, DSC and SEM, also employed to characterize pure substances and their physical mixtures.

Analysis of cannabinoids in fiber hemp plant varieties (Cannabis sativa L.) by high-performance liquid chromatography

SummaryAn analytical procedure was developed for the detection of neutral and acidic cannabinoids in herbal cannabis without the need of any preliminary derivatization. The method was used to assay cannabinoid content of over one hundred fiber hemp samples grown in different Italian localities and harvested at different maturation level degrees during the summer. No interferences were observed due to the vegetal matrix.The influence of genetic factors and environmental conditions on cannabinoid content is discussed; the results may be of interest to enhance potential of fiber hemp in compliance with law enforcement purposes.

Simultaneous separation and identification of hashish constituents by coupled liquid chromatography-mass spectrometry (HPLC-MS)

SummaryThis paper reports the use of liquid chromatography for the separation and determination of the major cannabinoids extracted from hashish samples. The direct coupling to the mass spectrometer enables the selective identification both of neutral and acidic cannabinoids. The developed method does not require any preliminary derivatization and should, therefore, be of interest in forensic analysis for simple and unequivocal determination of hashish constituents.

Novel antifouling agent zinc pyrithione: determination, acute toxicity, and bioaccumulation in marine mussels (Mytilus galloprovincialis).

Antifouling biocide zinc pyrithione (ZnPT) and its biological fate have received little attention because this compound was assumed not to be persistent in marine ecosystems. An analytical procedure was developed that has proved to be efficient and very sensitive in extracting ZnPT and its main secondary products, Zn and ionized pyrithione (PT(-)), from both seawater and biological samples, namely in the gills and digestive gland of the bioindicator species Mytilus galloprovincialis. Short-term experiments were carried out to investigate ZnPT toxicity and bioaccumulation. The effects on survival and tissue bioaccumulation of ZnPT and its secondary products were studied on adult mussels from a natural population, collected in the harbor area of Porto Santo Stefano (Italy) and exposed to sublethal doses of the biocide for up to 7 d. Zinc pyrithione was shown to be persistent in the experimental seawater in the short term. A basal level of ZnPT and ionized PT(-) was detected in the mussels, indicating that ZnPT availability in the sampling site is already high enough to induce a detectable accumulation in individuals of the native population. Zinc pyrithione rapidly accumulated in the tissues of the exposed mussels, proportionately to both exposure concentration and time, identifying the gills and digestive gland as important targets in the biological pathway of the contaminants. Even though the 7-d median lethal concentration (LC50) = 8.27 µM established here appears high with respect to reported ZnPT environmental concentrations, the results indicate that this biocide could represent a threat for marine organisms in coastal environments and that further investigations on its biological effects at sublethal doses are needed.

Properties of the racemic species of verapamil hydrochloride and gallopamil hydrochloride

It is well known that the stereoselective actions associated with the enantiomeric constituents of a racemic drug can differ markedly in their pharmacodynamic or pharmacokinetic properties. Nevertheless, molecular chirality manifests itself in the solid, that is, crystalline state. The aim of this work was to characterize the solid-state properties of verapamil HCl and gallopamil HCl, two well-known chiral calcium channel antagonists. The characterization of the solid state for the single enantiomers and equimolecular mixtures for both the calcium antagonists was performed by solid-state techniques such as Fourier transform infrared (FT-IR spectroscopy), X-ray powder diffractometry (XRD) and differential scanning calorimetry (DSC). The FT-IR spectra and XRD of the single enantiomers are different from those of the corresponding equimolecular mixture owing to their different crystalline structure. The thermal behavior of the racemates and pure enantiomers were examined by DSC, and the resultant experimental and theoretical binary phase diagrams are discussed. Spectroscopic solid-state techniques, such as FT-IR and XRD, are useful in combination with thermal analysis for characterizing the racemic species of chiral drugs. The data obtained prove that the equimolecular mixtures of both verapmil hydrochloride and gallopamil hydrochloride exist as racemic compounds. Determination of the enantiomeric purity of the enantiomers and racemic compounds of both the calcium antagonists analyzed was performed by DSC.

Resolution of the enantiomers of verapamil and gallopamil by chiral liquid chromatography-mass spectrometry

SummaryAn HPLC-CSP method has been developed for the separation of enantiomers of verapamil and gallopamil using the improved version of the α1-acid glycoprotein, chiral stationary phase as selector with a volatile mobile phase. The results of the investigation provide the conditions which allow direct coupling to a mass spectrometer. In addition, the simultaneous enantioseparation of both the enantiomeric pairs of verapamil and gallopamil was achieved.

Hair testing in clinical setting: Simultaneous determination of 50 psychoactive drugs and metabolites in headache patients by LC tandem MS.

Headache patients suffering from recurrent attacks are a population at risk of overuse and abuse of analgesic medications. Associated with triptans, the first-line drugs recommended for the acute treatment, these patients usually take other medications such as opioids analgesics for the attack treatment, antidepressants and antiepileptics for prophylaxis treatment and benzodiazepines, non-benzodiazepine hypnotics and antipsychotics for the treatment of comorbidities. Regular and frequent use of triptans, like of any other symptomatic analgesic, can cause chronic headache and medication-overuse headache (MOH). In these circumstances, a detoxification treatment is necessary and therefore the monitoring and follow-up of the patients are crucial to the success of the treatment. In the present study, a LC tandem MS method has been developed for the identification of 50 psychoactive drugs in human hair, including triptans, benzodiazepines and metabolites, analgesics, antiepileptic, antidepressants and metabolites, a non-benzodiazepine hypnotic (z-drug), antipsychotics and metabolites. Hair samples were decontaminated, pulverized and incubated overnight in methanol; the extracts were then purified by a new and rapid QuEChERS procedure and analyzed by LC-MS/MS under gradient elution with positive ionization MRM mode. The procedure was fully validated in terms of selectivity, linearity, limit of detection and lower limit of quantitation, precision and accuracy, carry-over, matrix effect, recovery and dilution integrity. The validated procedure has been applied to 234 real hair samples collected from headache patients with known type and dosage of the taken drugs; the obtained data could be of interest to evaluate the xenobiotic concentrations in patients with known therapy.

Simultaneous determination of pregnenolone sulphate, dehydroepiandrosterone and allopregnanolone in rat brain areas by liquid chromatography-electrospray tandem mass spectrometry.

Neurosteroids (NSs) are well known modulators of neuronal activity and by binding to different neuronal receptors are responsible for a broad spectrum of biological and pathophysiological conditions. Here, a sensitive liquid chromatographic-electrospray ionization-tandem mass spectrometric method (LC-ESI-MS/MS) has been developed and validated for the simultaneous determination in rat brain areas of three NSs, i.e. pregnenolone sulphate (PS), dehydroepiandrosterone (DHEA) and allopregnanolone (AP). NSs were extracted with methanol-formic acid, purified by Hybrid-SPE cartridges and subjected to LC-ESI-MS/MS without any preliminary derivatization or deconjugation procedure. Quantitation was performed by multiple reaction monitoring mode with the internal standard method, using deuterium-labelled analogues of the analyzed NSs. The proposed method provided for the first time a direct quantitative determination of PS without hydrolysis; in particular, PS concentrations were found significantly (p<0.01) higher in hippocampus, the brain area associated primarily with memory, than in cortical tissue of control rats, suggesting the important role of this NS in the process of memory formation. The developed method could be successfully applied to quantify simultaneously PS, DHEA and AP levels in brain tissue in order to study their changes during various neurodegenerative diseases and to investigate the role of PS in the brain.