Check out our New Publishers' Select for Free Articles

Advanced Drug Delivery Reviews (v.57, #8)

Editorial Board (pp. ii).

Non-invasive spectroscopic and imaging techniques in drug delivery by Karsten M�der Theme Editor (pp. 1083-1084).

Seeing is believing—visualizing drug delivery in vitro and in vivo by Harold Swartz (pp. 1085-1086).

Illustrations have always been essential in spreading new scientific and medical ideas. The extraordinary progress of spectroscopic and imaging methods allows the visualization of the performance of drug delivery systems under both in vitro and in vivo conditions. Detailed and quantitative information about the location and concentration of the drug and carrier can be obtained as a function of time, thereby enabling a more profound understanding of biological effects. This information is crucial to the design of optimized drug delivery systems. This issue of ADDR features novel, non-radioactive methods potentially useful for drug delivery scientists in selecting the most appropriate imaging techniques for solving the drug delivery problem at hand.

Keywords: Drug delivery; Imaging techniques; NMR-imaging; EPR-imaging; Biosusceptometry; In vivo spectroscopy

Optical imaging in drug discovery and diagnostic applications by K. Licha; C. Olbrich (pp. 1087-1108).

Optical imaging combines a variety of different diagnostic modalities which have shown great promise for biomedical imaging and as a tool in drug discovery. Several different principles to identify and characterize fundamental processes at the organ, tissue, cellular and molecular level have been exploited, supported by the design of novel imaging agents and biomolecular reporter systems.New optical imaging procedures will contribute considerably to the improvement of the knowledge of disease processes and the more efficient evaluation of drug effects in living laboratory animals. They may also find new diagnostic and therapeutic applications in human clinical practices. These techniques can be used in the field of molecular imaging to allow both visualization and quantification of molecular events associated with disease in a non-invasive and radiation-free manner using relatively simple equipment. The different aspects of imaging instrumentation and methods; the achievements in synthesis and evaluation of novel imaging agents and biochemical reporters; as well as the opportunities of optical imaging in drug delivery, drug discovery and imaging diagnostics will be discussed in this review article.

Keywords: Optical imaging; Fluorescent dyes; Reporter probes; Drug discovery; Animal imaging; Near-infrared dyes; NIR; GFP; Luciferase

Near-infrared spectroscopy and imaging: Basic principles and pharmaceutical applications by Gabriele Reich (pp. 1109-1143).

Near-infrared (NIR) spectroscopy and imaging are fast and nondestructive analytical techniques that provide chemical and physical information of virtually any matrix. In combination with multivariate data analysis these two methods open many interesting perspectives for both qualitative and quantitative analysis. This review focuses on recent pharmaceutical NIR applications and covers (1) basic principles of NIR techniques including chemometric data processing, (2) regulatory issues, (3) raw material identification and qualification, (4) direct analysis of intact solid dosage forms, and (5) process monitoring and process control.

Keywords: Noninvasive qualitative and quantitative analysis; Calibration and validation; Chemometrics; Raw material identification and characterization; Quality control of intact dosage forms; Process analytical technologies (PAT); Process monitoring

Pharmaceutical applications of Mid-IR and Raman spectroscopy by Siegfried Wartewig; Reinhard H.H. Neubert (pp. 1144-1170).

Mid-IR and Raman spectroscopy are versatile tools in pharmaceutics and biopharmaceutics, with a wide field of applications ranging from characterization of drug formulations to elucidation of kinetic processes in drug delivery. After an introduction to the basic principles of IR and Raman spectroscopy, new developments in applications of these methods for studying drug delivery systems, in particular topical drug delivery, will be reviewed.FTIR-ATR is a well-established standard method used to study drug release in semisolid formulations, drug penetration, and influence of penetration modifiers; it is also capable of in vivo studies.FTIR-PAS has been applied to measure drug content in semisolid and solid formulations, to determine drug penetration into artificial and biological membranes. The big advantage of this technique is the possibility of spectral depth profiling. However, FTIR-PAS is so far limited to in vitro investigations.Raman spectroscopy can be used to characterize the structure of colloidal drug carrier systems. Raman spectroscopy is readily applicable to in vivo studies, but such investigations must fulfill the relevant laser safety guideline.Recently, there has been tremendous technical improvement in vibrational microspectroscopy. FTIR imaging shows great promise in its ability to visualize the drug and excipient distribution in pharmaceutical formulations such as tablets and therapeutic transdermal systems, as well as to reveal the mechanism of drug release. Furthermore, this unique technique offers completely new possibilities to study the lateral diffusion of drugs.

Keywords: Mid-IR; Raman spectroscopy; Photoacoustic spectroscopy; FTIR-ATR; Drug delivery; Penetration

Monitoring drug delivery processes by EPR and related techniques—principles and applications by David J. Lurie; Karsten M�der (pp. 1171-1190).

Electron Paramagnetic Resonance (EPR, or ESR) is a powerful non-invasive spectroscopic tool that can be used to monitor drug release processes in vitro and in vivo. Furthermore, spatial dissolution can be achieved by means of EPR-Imaging. The article introduces the basics of EPR and EPR-imaging. It discusses also the challenges of in vivo spectroscopy and imaging and presents information about new developments such as longitudinally detected EPR (LODEPR) and Proton Electron Double Resonance Imaging ((PEDRI). Examples of the usefulness of EPR in the field of drug delivery include the measurement of microviscosity and micropolarity, the direct detection of drug release mechanisms in vitro and in vivo, the monitoring of microacidity in biodegradable polymers and the characterisation of colloidal drug carriers.

Keywords: ESR; EPR; Drug delivery; PEDRI; Overhauser imaging; EPR imaging; In vivo EPR

Pharmaceutical applications of magnetic resonance imaging (MRI) by J. Craig Richardson; Richard W. Bowtell; Karsten M�der; Colin D. Melia (pp. 1191-1209).

Magnetic resonance imaging (MRI) is a powerful imaging modality that provides internal images of materials and living organisms on a microscopic and macroscopic scale. It is non-invasive and non-destructive, and one of very few techniques that can observe internal events inside undisturbed specimens in situ. It is versatile, as a wide range of NMR modalities can be accessed, and 2D and 3D imaging can be undertaken. Despite widespread use and major advances in clinical MRI, it has seen limited application in the pharmaceutical sciences. In vitro studies have focussed on drug release mechanisms in polymeric delivery systems, but isolated studies of bioadhesion, tablet properties, and extrusion and mixing processes illustrate the wider potential. Perhaps the greatest potential however, lies in investigations of pharmaceuticals in vivo, where pilot human and animal studies have demonstrated we can obtain unique insights into the behaviour of gastrointestinal, topical, colloidal, and targeted drug delivery systems.

Keywords: MRI; NMR; Magnetic resonance imaging; Microscopy; Pharmaceutical; Dosage forms

Magnetic Marker Monitoring: An application of biomagnetic measurement instrumentation and principles for the determination of the gastrointestinal behavior of magnetically marked solid dosage forms by Werner Weitschies; Olaf Kosch; Hubert M�nnikes; Lutz Trahms (pp. 1210-1222).

Magnetic Marker Monitoring offers an alternative to investigate the behavior of solid dosage forms in the organs of the gastrointestinal tract without the need to apply radiation. For Magnetic Marker Monitoring, the dosage form is marked as a permanent magnetic dipole by the incorporation of small amounts of ferromagnetic material, as for example the colorant black iron oxide, and subsequent magnetization. Thereby, the dosage form is labeled as the source of a well defined magnetic field, which can be measured using a measurement technique that is established for biomagnetic investigations. Using the established concepts for magnetic source localization, the three dimensional localization and orientation as well as the strength of the magnetic source can be reconstructed from these magnetic measurement data as a function of time. Furthermore, it is possible to gain quantitative information on the disintegration of dosage forms in vivo. Examples are given for results obtained concerning the esophageal transit, the gastric and the intestinal behavior of capsules and tablets.

Keywords: Magnetic Marker Monitoring; MMM; Gastrointestinal transit time; Solid dosage forms; Pharmacokinetics; Magnetic Moment Imaging; MMI

AC biosusceptometry in the study of drug delivery by L.A. Cor�; F.G. Romeiro; M. Stelzer; M.F. Am�rico; R.B. Oliveira; O. Baffa; J.R.A. Miranda (pp. 1223-1241).

Conventionally, pharmaceutical substances are administered orally because the gastrointestinal tract possesses the appropriate features for drug absorption. Nevertheless, the gastrointestinal tract physiology is complex and influenced by many factors. These factors must be completely understood for the optimization of oral drug delivery systems. Although in vitro tests provide information about release and drug absorption profiles, in vivo studies are essential, due to the biological variability. Several techniques have been employed in an attempt to conveniently characterize the behavior of solid dosage forms in vivo. The noninvasive biomagnetic technique of alternate current biosusceptometry (ACB) has been used in studies focusing on gastrointestinal motility and, more recently, to evaluate the performance of magnetic dosage forms. This article will discuss the main characteristics of AC biosusceptometry and its applicability for determination of the relationship between the human gastrointestinal tract and orally administered pharmaceutical dosage forms.

Keywords: AC susceptometer; Gastrointestinal motility; Solid dosage forms; Biomagnetic measurement; Magnetic marker; Magnetic tracer

Sections

Personal tools

Advanced Drug Delivery Reviews (v.57, #8)

Sections

Personal tools

Local resources

Advanced Drug Delivery Reviews (v.57, #8)