Gastrointestinal Tract as a Major Route of Pharmaceutical Administration
Shayne C. Gad in Toxicology of the Gastrointestinal Tract, 2018
Absorption is defined as the transfer of a substance from its site of entry to the circulatory or lymphatic system. The rate and efficiency of absorption of any substance administered orally are dependent upon numerous factors such as: Patient age, gender, disease stateDisintegration and drug dissolution: foodstuffs, GI tract pH, pKa, solubility, lipophilicity, partial size, rate of peristalsisGI tract permeation: food–drug interactions, uptake and efflux transportersDrug to portal vein: hepatic metabolism such as CYP 450 enzymes, drug–drug interactions, protein binding
Small Animal Handling, Care, and Anesthesia
George C. Kagadis, Nancy L. Ford, Dimitrios N. Karnabatidis, George K. Loudos in Handbook of Small Animal Imaging, 2018
The subcutaneous route is frequently used for the administration of substances and fluids to prevent dehydration that can ensue following anesthesia and/or surgery, but rarely used for the administration of anesthetics. The rate of absorption will depend on the formulation of the substance. In general, the smallest needle should be used taking into account the viscosity of the substance. The recommended volumes are 10 mL/kg (mouse) and 5 mL/kg (rat) (Diehl et al. 2001). This would be approximately a 0.25 mL injection for a 25 g mouse. However, for subcutaneous fluid administration, up to 1 mL is normally given for a mouse. Normally the scapular region is the preferred site for subcutaneous injections; however, due to rodent’s loose skin, these injections can be given along the back and along the abdomen. A “tent” of skin should be created by lifting the skin in the area, and the needle should be inserted at an angle into the tented area. The entire needle should be placed into the subcutaneous space to ensure that the injected substance does not leak out of the puncture site. Before injecting, aspiration should occur to ensure that the needle has not penetrated a blood vessel or exited the skin, in which case air will be aspirated.
Modelling and analysis of skin pigmentation
Ahmad Fadzil Mohamad Hani, Dileep Kumar in Optical Imaging for Biomedical and Clinical Applications, 2017
The Beer–Lambert law relates the absorption of light to the properties of the material through which the light is travelling. The law formulates that there is a logarithmic dependence between the transmission, T, of light through a substance and the product of the absorption coefficient of the substance, α, and the distance the light travels through the material (i.e., the path length), ℓ. The application of Beer–Lambert law and its modification for skin have been reported by Shimada [69,143,144]. This technique uses the spectral distortion induced by multiple scattering via a linearised equation relating the general tissue attenuation to the tissue absorption coefficient, μa. The absorbance, A, is defined from the reflectance, R, of the skin, which is regarded to be a semi-infinite medium.
MPS dose reconstruction for internal emitters: some site-specific issues and approaches
Published in International Journal of Radiation Biology, 2022
Richard W. Leggett, Keith F. Eckerman, Michael Bellamy
For the most part, the biokinetic models applied in the dose reconstructions conducted to this point in the MPS are the models applied in ICRP Publication 68 (1994a). For the LANL study and for some special cases at Rocketdyne and Mound described in a later section of this article, the models of Publication 68 have been replaced with updated or site-specific biokinetic models. For most inhalation exposures at Rocketdyne, Mound, and Mallinckrodt, the applied respiratory model was the Human respiratory tract model (HRTM) introduced in ICRP Publication 66 (1994b) and applied in Publication 68. The ICRP originally provided three sets of parameter values for the HRTM describing different levels of solubility (‘absorption types’) of inhaled particles in the respiratory tract: Type F, representing fast dissolution and a high rate of absorption to blood; Type M, representing a moderate rate of dissolution and a moderate rate of absorption to blood; and Type S, representing slow dissolution and slow absorption to blood. These absorption types are referred to frequently in this article and, unless otherwise indicated, refer to their original definitions.
Bortezomib-loaded lipidic-nano drug delivery systems; formulation, therapeutic efficacy, and pharmacokinetics
Published in Journal of Microencapsulation, 2021
Mohammad Mahmoudian, Hadi Valizadeh, Raimar Löbenberg, Parvin Zakeri-Milani
During the development of BTZ, it was thought that BTZ would be orally bioavailable. Adams and Stein (1996) reported good oral potency and long half-life (24 h in rat) for BTZ in the treatment of rheumatoid arthritis (Adams and Stein 1996). However, there is one more data pertaining to oral delivery of BTZ and currently, BTZ is approved for SC/IV administration. In order to oral delivery of BTZ, biopharmaceutical class (BC) of BTZ was predicted based on the intestinal permeability studies in rats. It was predicted that BTZ has low intestinal permeability and high solubility (BC III). Drug absorption is the process of drug entrance from the site of administration into the bloodstream. Based on the biopharmaceutical classification system, drug solubility, and permeability can be considered as absorption limiting factors for orally delivered drugs. Therefore, the low intestinal absorption can be considered as a rate-limiting factor for oral absorption of BTZ (Raza et al. 2017).
Microwave-assisted and one-step synthesis of PEG passivated fluorescent carbon dots from gelatin as an efficient nanocarrier for methotrexate delivery
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2019
Nasser Arsalani, Parinaz Nezhad-Mokhtari, Esmaiel Jabbari
Figure 3(a) displays the UV–vis absorption and PL spectra of the CDs-PEG. The absorption spectrum showed a characteristic weak absorption peak at 290 nm. When it was excited at 290 nm, the PL spectra exhibited a peak position at 430 nm. In addition, the PL emission of the CDs-PEG is intensely dependent on the excitation wavelength, regularly decreased with the increasing of excitation wavelength. Such an observation is similar to that of QDs, which may be representing the optical selectivity of variously sized NPs (the quantum effect) or various emissive traps on the CDs surface. Moreover, abundant functional groups such as amines and carboxyl acids, which are presented simultaneously during the microwave pyrolysis, may introduce different defects onto the surface of CDs, acting as excitation energy traps and leading to different PL properties [3]. The QY of CDs-PEG solution was calculated at around 34% using QS as a reference. In a parallel control experiment, if the PEG passivation was eliminated, a similar colour change and UV–vis absorption spectrum were detected. However, these non-passivated NPs presented a poor luminescence emission spectrum (Figure 3(b)). It should be pointed out that the polymeric passivation agent contains no visible or near-UV chromophores and so no emission should be gained at visible wavelengths. Therefore the observed colourful luminescence emission may be owing to the surface-passivated NPs [7].
Related Knowledge Centers
- Atom
- Penetration Depth
- Radiant Energy
- Intensity
- Attenuation Coefficient
- Molar Absorption Coefficient
- Beer–Lambert Law
- Mass Attenuation Coefficient
- Absorption Cross Section
- Cross Section