Mindblown: a blog about philosophy.
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Metabolism Of Drugs
Drugs are chemical substances, which interact with living organisms and produce some pharmacological effects and then, they should be eliminated from the body unchanged or by changing to some easily excretable molecules. The process by which the body brings about changes in drug molecule is referred as drug metabolism or biotransformation. Enzymes responsible for metabolism…
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Dose Response Relationship
The exact relationship between the dose and the response depends on the biological object under observation and the drug employed.When a logarithm of dose as abscissa and responses as ordinate are constructed graphically, the “S” shaped or sigmoid type curve is obtained.The lowest concentration of a drug that elicits a response is minimal dose, and…
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Site Of Drug Action
A drug may act:(i) Extracellularly e.g: osmotic diuretics, plasma expanders.(ii) On the cell surface e.g.: digitalis, penicillin, catecholamines(iii) Inside the cell e.g.: anti-cancer drugs, steroid hormones.
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Receptor And Non-Receptor Mechanisms
Most of the drugs act by interacting with a cellular component called receptor. Some drugs act through simple physical or chemicalreactions without interacting with any receptor.• Receptors are protein molecules present either on the cell surface or with in the cell e.g. adrenergic receptors, cholinoceptors, insulin receptors, etc.• The endogenous neurotransmitters, hormones, autacoids and most…
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Drugs Are Obtained From
Minerals: Liquid paraffin, magnesium sulfate, magnesium trisilicate, kaolin, etc. Animals: Insulin, thyroid extract, heparin and antitoxin sera, etc. Plants: Morphine, digoxin, atropine, castor oil, etc. Synthetic source: Aspirin, sulphonamides, paracetamol, zidovudine, etc. Micro organisms: Penicillin, streptomycin and many other antibiotics. Genetic engineering: Human insulin, human growth hormone etc.Out of all the above sources, majority of…
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Pharmacodynamics
Pharmacodynamics (PD) is the study of the effect of a medicine on the body. There are two ways a medicine can affect the body: A medicine can change conditions within the body, or A medicine can interact with specific parts of the body on a cellular or sub-cellular level. The primary objective of pharmacodynamic studies is to…
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Bioequivalence
Birkett (2009) describes bioequivalence as “a clinical definition referring to two formulations of a drug”. “Drugs are considered bioequivalent if the extents and rates of absorption of drug from them are so similar that there is likely no clinically important difference between their effects” The EMA states “Two medicinal products containing the same active substance are considered bioequivalent if…
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Bioavailability
In order to understand and interpret pharmacokinetik measurements the concept of bioavailabity should be known. To note: Absorption and bioavailability are related concepts. In Pharmacokinetics Made Easy (Birkett, 2009) defines bioavailability as: “Bioavailability is the fraction of the dose which reaches systemic circulation as intact drug” Other definitions are possible and perhaps even desirable. The flaw of most definitions is the tendency to ignore the…
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Measuring Pharmacokinetics
Based on data gathered during pharmacokinetic studies, Pharmacokinetics (PK), applying scientific and mathematical models helps to predict and understand the time course of Absorption, Distribution, Metabolism, and Excretion of medicines in the body.. This allows scientists to assess the relationship between the medicine’s beneficial and toxic effects, and to predict the safety and tolerability of the medicine in humans. Data gathered during pharmacokinetic studies…
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Excretion
It refers to how the body gets rid of a medicine or its metabolites. There are three main routes of elimination: kidneys (urine), liver, and bowel (bile in faeces). Most medicines are excreted as active, partially active, or inactive metabolites by the kidneys. Infants and elderly have underdeveloped or impaired abilities to metabolise and excrete…
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