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Pharmacodynamics and Pharmacokinetics

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Pharmacodynamics and Pharmacokinetics

Pharmacodynamics is the study of drugs’ effects on living organisms. This includes observing how the drug responds, depending on the concentration of the drug in the organism. It is simply how an organism responds after administration of any given drugs. The Pharmacodynamics of a drug may be affected by many things. Some of physiological changes that can affect it include aging, allergy or administration of other drugs. Some other disorders that could influence pharmacodynamics are diseases like diabetes, malnutrition mutation of genes among others. The disorder can change receptors by decreasing their sensitivity (Kwon, 2002).

Pharmacodynamics has both negative and positive effects on a patient. The positive ones are blending well with enzymes, ion, binding with receptors among others. The negative ones are possibility of mutating cells, addiction, abnormal conditions, which may be chronic among others. Drugs have different therapeutic windows so they should be handled accordingly. Those with a smaller therapeutic window should be closely monitored. They are likely to become ineffective easily or cause severe effects ((Rosenbaum, 2011).

Pharmacokinetic is described as how the body acts on the drugs. Four processes are involved in the given period. They include absorption, distribution metabolism and excretion. There is also another important process called liberation. This process releases the drug from its formation. All the five processes show how the body affects the drugs. Factors affecting pharmacokinetics are location of where the drug was administered and the dose of drug. These two factors mainly influence the rate of absorption (Shagel, Wu-Pong & Yu, 2005). This is why a critical patient is injected where the drug will spread fast in the body. Pharmacokinetics of drugs influences length of time and intensity of the drugs effects. It also depends on the chemical structure of the drugs and the patient factors. Some of them are age, genetics, cosmetics and other factors. Initially, it was a patient who determined his or her pharmacokinetics. This is because of his or her needs. The dose was continually administered until the patient’s body gets enough. A physician should study pharmacokinetics the drugs he or she uses most (Kwon, 2002).

There are several routes of administering drugs. They are mouth, enteral, mucosal, parenteral and percateneous. In normal circumstances, patients take medication via their mouths. This becomes impossible if there is vomiting. The physician seeks another route of administration. A patient’s illness determines which route will be used to administer drugs. For example, an infection on the skin calls for an ointment, which will be spread on the infection. If the patient is unconscious and requires a faster way of absorbing medication then parenteral would be convenient route (Rosenbaum, 2011).

Cellular metabolism has two major routes. The reason for either route to be used depends on what is happening to the body energy. Catabolism happens when energy is being produced. Organic matter is broken down through cellular respiration and energy is harvested. Anabolism process utilizes energy in the formation of cell components. Metabolism has chemical reactions, which are divided further to pathways. When a chemical goes through this pathway, it will be converted to another chemical. Metabolism is important because it keeps organisms alive (Kwon, 2002).

All body tissues have some ability to metabolize drugs. However, the major organ responsible for this function is the liver. This organ is appropriate for drug metabolism because of its adaptation. It is large and contains high concentrated enzymes, suitable for metabolizing drugs. These chemicals convert drug elements into useful substance called metabolites. The liver has smooth endoplasmic reticulum, which makes it possible for drug metabolism. Other sites used for metabolizing drugs are lungs, skin, kidney, epithelial cells and gastrointestinal tract. These organs are also responsible for toxicity reactions (Shargel, Wu-Pong & Yu, 2005).

Reference:

Kwon, Y. (2002). Handbook of essential pharmacokinetics, pharmacodynamics and drug metabolism for industrial scientists. New York: Kluwer Academic Publishers.

Rosenbaum, S. (2011). Basic pharmacokinetics and pharmacodynamics: An integrated textbook and computer simulations. Hoboken, N.J: John Wiley & Sons.

Shargel, L., Wu-Pong, S., & Yu, A. B. C. (2005). Applied biopharmaceutics & pharmacokinetics. New York: Appleton & Lange Reviews/McGraw-Hill, Medical Pub. Division.