Absorption, Distribution, Metabolism and Excretion of Drugs Essay
Absorption, Distribution, Metabolism and Excretion of Drugs Essay
When a drug is taken there are four vital process that are involved. This process include absorption, distribution, metabolism and excretion from the body systems.
Absorption of drugs
This is the process which drugs move from the site of intake into the blood stream. Majority of the drugs taken are observed through inactive absorption but some may need specialized transporter intermediated transport. Given that lesser particles diffuse rapid than large molecules, lipid soluble non- ionized drugs are rapidly observed into the blood stream. Blood flow and pain stress are some factors that affect drug absorption into the body.Absorption, Distribution, Metabolism and Excretion of Drugs Essay. The type of drug taken is differently absorbed into the body system. Acidic drugs are well absorbed into the stomach because of acidic conditions while basic drugs are absorbed into the intestine due to availability of alkaline conditions. Most drugs are always absorbed in the small intestine compared to the stomach because time taken in the stomach is less and stomach offers less surface area for absorption. If alkaline drugs are taken after taking meal its absorption is reduced greatly while if acidic drug is taken after meal its action is rapidly noticed due to owing of gastric absorption. Drugs contains some molecules which require aqueous environment to be absorbed then the other insoluble part is absorbed into the blood stream. Presence of bile juices in the intestines plays critical role in aiding recovery of drugs and the subsequent absorption. Majority of drugs that are unsolvable in water, therefore bile juices in the small intestine emulsify them to make them more absorbable into the body. Other drugs are absorbed into the body through active transport. If drugs are introduced into the blood through muscles intravenous layer absorption takes place but they are dependent on the type of the drug taken. Absorption, Distribution, Metabolism and Excretion of Drugs Essay.
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Distribution of drugs
This is the process through which drugs move throughout the body system. Movement of drugs is greatly determined by blood flow to the body tissues. This can also be defined as the capability of drugs to enter into vasculature system and the ability to enter body cells. Distribution of drugs takes place through the following; plasma protein binding, given that blood stream has great ability to transport any insoluble substances some drugs bind themselves to proteins which are very amphipathic in nature. Majority of drugs that travel through the plasma are partially in solution form and partially attach to the plasma protein. In this case the attached part is inactive and the unattached part is active. Absorption, Distribution, Metabolism and Excretion of Drugs Essay. Generally acidic drugs binds to albumin and alkaline drugs to alpha1- acid glycoprotein. Another process is tissue distribution, after absorption of drugs majority of them are spread into the blood stream to be transported to various body parts where they bring their outcome. The degree to which drugs are likely to gather in the body tissue is greatly depends on the lipophilicity and the normal flow of blood to the body tissues, therefore greatly perfused organs tend to take utmost all drugs absorbed into the body. Absorption, Distribution, Metabolism and Excretion of Drugs Essay.
Metabolism of drugs
This is a process through which drugs are transformed within the body making them more hydrophilic so that they can be easily removed from out of the body system by the kidney. This process is vital because some of the drugs taken have some chemical substances that are foreign in the body and may have adverse effects if not excreted. Metabolism ensures drugs are excreted out of the body. During metabolism of drugs there some enzymes play critical part in breaking down molecules. This enzymes include; “phase I metabolism enzymes”, this alter the drug chemically through oxidation, reduction and hydrolysis. They may also remove or add active groups to this drugs. Phase II metabolism enzymes, this includes conjugation of drugs with polar groups thus rendering them to be possible for excretion. Main sites of breakdown of drugs include, liver and kidney, thus when drug is extracted hydrophilic they are definitely emitted out of the body through bile and urine without substantial reabsorption. Absorption, Distribution, Metabolism and Excretion of Drugs Essay.Another process is enzyme induction, given that there are some drugs that may lead to increased production of enzymes to speed up the rate of metabolism of drugs thus there is high dose of drug that is required to achieve the therapeutic effect. Enzyme inhibition, in some cases some drugs may result into enzyme inhibition of some enzymes. This may lead to accumulation of drugs in the body therefore metabolism ensures rapid excretion of drugs to minimize side effects resulting from toxicity.
Excretion of drugs
This is removal of substances from the body system. The main ways through which drugs are excreted from the body include, renal and biliary excretion. Renal filtration contributes greatly to the excretion of drugs from the body. Drugs that are bound to plasma membrane generally remain in the circulation. Most of the drugs may be excreted unchanged or others may be expelled out of the body as metabolites in the urine or bile. Some drugs may be removed from the body through natural means like tears, urine and saliva though in small traces. Absorption, Distribution, Metabolism and Excretion of Drugs Essay.
Reference
Richard A. Lehne (2013). Pharmacology for Nursing care (8th ed.). ISBN: 9781437735826
