3870137066

NMR CIAŁA STAŁEGO - ZASTOSOWANIA W FARMACJI I DIAGNOSTYCE MEDYCZNEJ 123

ABSTRACT

Some characteristic features, distinguishingNMR in solution and solid phase, are briefly described. The techniąues of magie angle spinning, cross-polarization, as well as the experiments with variable cross-polarization time and dipolar-dephasing pulse seąuences are illustrated. The spectra measured for Solutions are frequently used as an aid in the assignment of solid-state ones. The differences A = S ,    -

£ statc ^{are ex}pl^a>^ned in terms of conformational effects (resulting from frozen intramolecular reorientation in the solids) and intra- and intermolecular interactions (hydrogen bonds and also short intermolecular contacts in the crystals).

Solid-state NMR spectroscopy has become an important technique in the field of pharmaceutical Sciences. Solid-state techniques are used for the characterization of pharmaceutical solids: drug substances and dosage forms (tablets) and their mu-tual interactions. Structural information on solid antibiotics (penicillin salts, eryth-romycin A, chloramphenicol and its derivatives), anticoagulants (warfarin, sintrom), antimalaria (artemizinin) or anxiolytic drugs (buspirone and its analogues) was ob-tained by the analysis of ^l3C CP MAS spectra. Frequently exploited area is polymor-phism because pharmaceutical polymorphs can display different solubilities, disso-lution rates and bioavailability. Polymorphic forms ofsteroids (testosterone, predni-solone, cortisone) and 4-azasteroids (finasteride) and of numerous other drugs (e.g. AZT, paracetamol, phenobarbital) have been detected. Solid-state NMR has thus an ability to differentiate polymorphs, determine asymmetry in the crystal unit celi and investigate molecular motions within the solids.

MAS NMR spectra can be recorded for powdered tablets, enabling fast identi-fication ofthe active substance. Few examples of forensic applications include „Exta-sy” and Viagra tablets. The technique ideally lends itself to the studies on drug-excipients interaction, possible conversions of the drug during processing and stora-ge can be followed.

Multinuclear solid State NMR is also useful in characterization of materials and tissues removed during surgery (bones, brain tumors, urinaiy Stones).

Keywords: ¹³CP MAS NMR, 'H MAS NMR, solid-state, polymorphism Słowa kluczowe: ¹³CP MAS NMR, 'H MAS NMR, ciało stałe, polimorfizm