File Name: physical and chemical properties of drugs .zip
Nanoparticles often have unique physical and chemical properties. For example, the electronic, optical, and chemical properties of nanoparticles may be very different from those of each component in the bulk. At the nanoscale , materials behave very differently compared to larger scales and it is still very difficult to predict the physical and chemical properties of particles of such a very small size. The principal parameters of nanoparticles are their shape, size, surface characteristics and inner structure. Nanoparticles can be encountered as aerosols solids or liquids in air , suspensions solids in liquids or as emulsions liquids in liquids.
The observation that marketed oral drugs have restricted physicochemical properties, which are distinctly different from current medicinal chemistry, provides a viable hypothesis to tackle the attrition problem. The history of medicinal chemistry suggests that balancing the lipophilicity or hydrophobicity of drug candidates is central to successful outcomes. Thus, while highly lipophilic molecules often have high affinity for the biological target, in general they show increased risk of poor ADMET properties and increased attrition in drug development. While it is possible to discover drugs that lie at the perimeter of oral drug-like space, a portfolio composed of such molecules would suffer predictable high attrition, and would require serendipity for its success. The common practice of primarily optimizing potency in vitro has the potential to introduce unnecessary bias to drug design practice. A solution is to make better use of multi-parameter optimization, where emphasis is placed collectively on the potency and ADMET properties expected to modulate the specific disease.
Calculation of pH value of aqueous solutions of strong and weak acids and bases. Acidic and basic strength and p K a. Henderson—Hasselbalch equation. Ionisation of drug molecules. Activity, ionic strength and dielectric constant. Stereochemistry of drugs.
Physicochemical Principles of Pharmacy pp Cite as. In this chapter we will examine some of the physicochemical properties of drugs in aqueous solution which are of relevance to such liquid dosage forms as parenteral solutions, eye drops and irrigations. Some basic thermodynamics will be introduced and the concept of thermodynamic activity, which is an important parameter in determining drug potency, will be discussed. It is important that parenteral solutions are formulated with osmotic pressure similar to that of blood serum; in this chapter we will see how to adjust the tonicity of the formulation to achieve this aim. Most drugs are at least partially ionised at physiological pH and many studies have suggested that the charged group is essential for biological activity. We will look at the influence of pH on the ionisation of several types of drug in solution and consider equations that allow the calculation of the pH of solutions of these drugs. Unable to display preview.
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Aspirin , also known as acetylsalicylic acid ASA , is a medication used to reduce pain , fever , or inflammation. One common adverse effect is an upset stomach. A precursor to aspirin found in leaves from the willow tree has been used for its health effects for at least 2, years.
If your institution subscribes to this resource, and you don't have a MyAccess Profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus. Please consult the latest official manual style if you have any questions regarding the format accuracy. Biopharmaceutics is the study of the physicochemical properties of the drug and the drug product, in vitro , on the bioavailability of the drug, in vivo , to produce a desired therapeutic effect. Biopharmaceutics links the physical and chemical properties of the drug and the drug product to their performance, in vivo. A primary concern in biopharmaceutics is the bioavailability of drugs.
All matter has physical and chemical properties. Physical properties are characteristics that scientists can measure without changing the composition of the sample under study, such as mass, color, and volume the amount of space occupied by a sample. Chemical properties describe the characteristic ability of a substance to react to form new substances; they include its flammability and susceptibility to corrosion. All samples of a pure substance have the same chemical and physical properties. For example, pure copper is always a reddish-brown solid a physical property and always dissolves in dilute nitric acid to produce a blue solution and a brown gas a chemical property. A physical property is a characteristic of a substance that can be observed or measured without changing the identity of the substance. Silver is a shiny metal that conducts electricity very well.
Ты уходишь. - Ты же знаешь, что я бы осталась, - сказала она, задержавшись в дверях, - но у меня все же есть кое-какая гордость. Я просто не желаю играть вторую скрипку - тем более по отношению к подростку.