Solid delivery technique

X-ray patterns can be obtained using either a powder diffractometer or a camera. Currently, diffractometers find widespread use in the analysis of pharmaceutical solids. The technique is usually nondestructive in nature. The theory and operation of powder diffractometers is outside the scope of this discussion, but these topics have received excellent coverage elsewhere. Instead, the discussion will be restricted to the applications of X-ray powder diffractometry (XRD) in the analysis of pharmaceutical solids. The United States Pharmacopeia provides a brief but comprehensive introduction to X-ray dif-fractometry. The use of XRD in the physical characterization of pharmaceutical solids and in the characterization of controlled release delivery systems have been discussed earlier. ... 

Other modern research has highlighted the importance of CG for different drug delivery systems, as follows CG and chitosan combinations (2 3,3 2, and 4 1) as a carriers for buccal drug delivery of 10 mg propranolol hydrochloride mucoadhesive tablets coated on one face with 5% (w/v) ethyl cellulose or formulated using a direct compression technique [226] enhancement of solubility, dissolution rate and bioavailability of poorly water-soluble drug lovastatin using modified CG (by heating) and solid dispersion techniques [227] formulation and evaluation of nimesulide orodispersible tablets... 

Table 8.36 lists the main classical and newer approaches to solid sampling for elemental analysis. Little work on the introduction of solids into flames has been reported, because of problems of sample delivery and the relatively low source temperature. In arc and spark emission and in laser ablation as a sampling technique, the ablated sample material cannot be determined exactly. The limitations of arc or... 

Rotational-echo double-resonance (REDOR)(75,79) is a new solid-state NMR technique which is sensitive to through-space carbon-nitrogen interactions between selectively 13C and 15N-enriched sites separated by up to 5A (20-22). The parameter directly measured in a REDOR experiment is the heteronuclear dipolar coupling constant DCN, which is in itself proportional to the inverse third power of the intemuclear distance, rCN. It is this dependence on (icn)3 which accounts both for REDOR s ability to accurately measure short distances and its insensitivity to longer-range interactions. As a technique which can probe, in detail, intermolecular interactions over a distance range of 5A, REDOR is well suited to studying the distribution of small selectively-labeled molecules in polymer delivery systems. 

The degradation of proteins in the solid state occur to a lesser extent and typically via different mechanisms than those that occur in solution [109,110]. Lyophilization is currently the more common technique in the manufacture of dried therapeutic proteins however, there is increasing interest in the use of spraydrying, owing to the unique physical nature of the spray-dried powder and its potential usefulness in protein drug delivery. 

Controlled delivery of collections of molecules onto a substrate with nanometre resolution can be achieved with the tip of an AFM. This positive printing mode technique is called dip-pen nanolithography (DPN) and its working principle is illustrated in Fig. 3.27. DPN uses an AFM tip as a nanopencil, a substrate as the paper and molecules with a chemical affinity for the substrate as the ink. Capillary transport of molecules from the AFM tip to the solid substrate is used in DPN to directly write patterns consisting of a relatively small collection of molecules in submicrometre dimensions. The hrst example introducing the technique was the transfer of octadecanethiol onto gold surfaces (Piner et al, 1999). 

Organizational characteristics of surface-active molecules have been studied by several researchers due to their applications in many areas such as personal care, polymerization, catalysis, drug delivery, separation and purification, enhanced oil recovery and lubrication. The structure of supramolecular organized assemblies formed in different solvents, when a critical concentration is exceeded, determines their properties such as solubilization [1-3], catalysis [1,4-6], adsorption [7-11] and flocculation [12,13]. As such, many techniques have been used to determine their structural properties. In this paper, the results obtained using fluorescence probing for properties of assemblies in solution and at solid-liquid interfaces are discussed in detail after a brief review of relevant assemblies formed by them. 

In terms of beam delivery, the DLW method is based on optical microscopy, confocal microscopy [4,6,13] and laser tweezers [14] (for reviews on laser tweezers see [ 15,16]). These techniques allow for a high spatial 3D resolution of a tightly focused laser beam with optical exposure of micrometric-sized volumes via linear and nonlinear absorption. In addition, mechanical and thermal forces can be exerted upon objects as small as 10 nm molecular dipolar alignment can be controlled by polarization of light in volumes of with submicrometric cross-sections. This circumstance widens the field of applications for laser nano- and microfabrication in liquid and solid materials [17-22]. 

Given the complexity in molecular transport in tissues, understanding mechanisms of convection, diffusion, and binding in the interstitial space regardless of administration techniques may provide the means to overcome transport barriers for more uniform and adequate delivery of large therapeutic agents in solid tumors. 

Bugay DE. Characterization of the solid-state spectroscopic techniques. Adv Drug Delivery Rev 2001 48 43-65. 

Although a wide range of polymers have been investigated with various cyclodex-trins, these studies mainly focused on the IC preparation techniques and characterization of solid phases. The solution properties, such as the self - assembly behavior, dissociation, particle size an surface activity, were not commonly reported. These solution properties, especially the assembly and surface behavior, are vital for the potential applications of such systems in biomedical science, such as in controlled drug delivery. 

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