Drugs in Pregnancy and Lactation
A. S. Curry, J. V. Hewitt in Biochemistry of Women: Clinical Concepts, 1974
The metabolism of drugs takes place especially in the liver but also in other tissues, such as the blood, the gastrointestinal tract, kidneys, lungs, and skin.1,2 The metabolic reactions that occur have been classified into two major classes, namely, biotransformations, in which the drug molecule undergoes a chemical change (oxygenation, oxidation, reduction, or hydrolysis), and conjugations, in which the synthesis of a derivative of the drug, or of its metabolite, occurs (acetylation, methylation, glucuronide, sulfate, glycine, and glutathione formation). For example, the hypnotic drug phenobarbital undergoes oxygenation to form p-hydroxyphenobarbital, which is subsequently conjugated to yield p-hydroxyphenobarbital glucuronide, which is then more rapidly excreted from the body (see Figure 1). The hepatic enzyme system that is responsible for the hydroxylation of drugs is located in the endoplasmic reticulum (microsomes) and comprises the carbon monoxide-binding pigment, cytochrome P-450, which together with NADPH-cytochrome c reductase, cytochrome P-450 reductase, and possibly other enzymic entities, form the electron transport chain catalyzing the O2- and NADPH-dependent incorporation of oxygen into the substrate (see Figure 2).
Cutaneous Photosensitization
David W. Hobson in Dermal and Ocular Toxicology, 2020
Responses of biological systems to light are based on chemical reactions initiated by molecular absorption of light. Absorption of light by specific molecules in the system results in the promotion of electrons to higher energy states. These “excited-state” molecules possess the necessary energy of activation required to undergo a photochemical reaction. The absorbing molecule may photochemically react in a reagent manner with adjacent biomolecules and thus be exhausted in the reaction or it may resemble a catalytic mechanism causing a modification of a biomolecule without itself undergoing a permanent chemical change. The latter mechanism allows the photosensitizing molecule to return to the unexcited (ground) state and thus be available to absorb another quantum of light and repeat the photochemical reaction cycle again.
Basic Principles in Photomedicine and Photochemistry
Henry W. Lim, Nicholas A. Soter in Clinical Photomedicine, 2018
Internal conversion is a photophysical process that returns the excited singlet state molecule to the ground state without a chemical change. The energy of the excited state is dissipated as heat, and internal conversion is described as a “radiationless decay” process. Usually the amount of heat produced is not detectable because it is very small and dissipates quickly in the tissue. When a high-intensity light source is used that excites many molecules in a small volume of tissue, a temperature rise may result if the molecules return to the ground state by internal conversion. A laser is almost always required to produce a large number of excited state molecules in a small tissue volume. The thermal energy produced upon rapid internal conversion of hemoglobin molecules after excitation by a pulsed dye laser has been used in laser treatment of port wine stains. The heat deposited is believed to cause coagulation of blood and denaturation of proteins.
Recent approaches to ameliorate selectivity and sensitivity of enzyme based cholesterol biosensors: a review
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Anjum Gahlaut, Vinita Hooda, Vikas Dhull, Vikas Hooda
Biosensor is an analytical device which detects the biochemical change produced due to the presence of specific analyte. A signal is produced which is proportional to the concentration of the target analyte present in its proximity. Basic assembly of biosensor consists of recognition layer, transducer and processor. Recognition layer is the main sensing element of the biosensor; it is made up of biological component that can be an enzyme, a cell, antibody, receptor molecule or DNA. Recognition layer is immobilized either directly on transducer or on some other support present in its intimate contact. Transducer acts like a translator that recognizes the physico-chemical change (i.e. pH change, heat transfer, uptake or release of gases or specific ions, electron transfer and mass changes) and converts it into electronic signal and the processor converts it into readable digital output. Schematic representation of biosensor has been depicted in Figure 2. The concept of biosensor was pioneered by Clark for determination of glucose, thereafter concept has been explored widely for determination of various other molecules like cholesterol, lactate, uric acid, hCG, etc. Differentiating on the basis of type of transducer used, biosensors can be categorized into following:
Role of artificial intelligence and vibrational spectroscopy in cancer diagnostics
Published in Expert Review of Molecular Diagnostics, 2020
Ihtesham U. Rehman, Rabia Sannam Khan, Shazza Rehman
A wealth of data now exists, describing chemical structural changes associated with various human disease conditions, including cancers. There still is the unmet need for the creation of a single comprehensive and standardized database of these chemical change spectra for future applications and reference from where both the AI and ML can play a pivotal role in clinical applications. In addition, machine learning and data mining approaches have been advancing rapidly in recent years, with exciting new applications and it is anticipated that in the near future these combined approaches will provide a number of solutions not only to tackle cancer but also to facilitate a clearer understanding of other disease processes and biomaterials in a way that allows tailoring drugs and materials for a number of specific clinical applications.
Development of eplerenone nano sono-crystals using factorial design: enhanced solubility and dissolution rate via anti solvent crystallization technique
Published in Drug Development and Industrial Pharmacy, 2022
Ghada E. Yassin, Maha K. A. Khalifa
Khames et al. [6] obtained the same result of FTIR of raw EP while Fousteris et al. and Newa et al. reported the same FTIR results for Poloxamer 188 and PEG 6000 respectively [21,22]. As a result, all of the characteristic fingerprints in the raw drug spectra were replicated almost exactly in the same region in the spectra of EP at the physical mixture and the formulated sono-crystals, demonstrating that the EP and polymers have no significant interaction. From this comparison, it can be said that there was no chemical change occurred after the crystallization by using the organic solvent and ultrasonic energy. Also, the sonication is not having any impact on the drug morphology or its form. Abd-Elhakeem et al. [23] reported similar findings X- ray diffraction of raw EP while Sharma et al. and Heo et al. discussed the same results of poloxamer 188 and PEG 6000 [24,25]. The X-ray diffractograms of the physical mixture of EP and Poloxamer and PEG 6000 exhibited a reduction in the intensity for peaks, indicating partial alteration of the drug into amorphous form leading to increased solubility [10]. This decrease in intensity might be attributed to changes in crystal habit associated with particle size reduction [18]. Also it reveals that there is a little change in crystallinity of the drug after the sonication and these results are matched with Gandhi et al. when studying the development of nano-crystals of sirolimus using sonication based crystallization [26]. However, the characteristic peaks of crystalline EP were still detectable at their positions suggesting that the EP didn’t undergo structural modifications.
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