Top Best Pharmacokinetics Experts
Pharmacokinetics can be defined as the study of how ingested medication interacts with the human body from the moment it is ingested until it is completely excreted. The pharmacokinetics of medication is made up of four processes.
These processes include absorption, metabolism, distribution, and excretion. These processes are often influenced by how they are they are administered and how body organs work.
Pharmacokinetics describes the movement of drugs through the biological systems of the body. The pharmacokinetics processes can be divided into absorption, distribution, bioavailability, metabolism, and excretion.
Pharmacokinetics is used to study the beginning, duration, and intensity of the side effects of drugs. It helps us to understand how drugs move into our bodies, how they move into and out of the body.
Understanding pharmacokinetics helps practitioners to have flexibility when prescribing and giving out medication. This flexibility helps them to offer patients the best drugs with minimal risks and allows them to make necessary adjustments to suit the lifestyle and physiology of patients.
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Processes in Pharmacokinetics
- Absorption – it is through absorption that administered drugs get into the circulation system. absorption plays a role in determining the concentration and speed at which a drug gets to the targeted location. Drugs are usually administered in different ways including intravenous, oral, buccal, rectal, vaginal, intramuscular, intrathecal, otic, ocular, nebulized, transdermal, and inhaled. All the methods of drug administration mentioned have their advantages and disadvantages and characteristics of absorption.
Oral medications that delay the throat usually delay the start of the intended effects of the drug. This may cause damage to the mucosal. The low PH in the stomach reacts chemically with oral drugs before they get into the systematic circulation.
Bioavailability – this is the portion of the administered drug that makes it to the systematic circulation. Bioavailability depends on the drug properties and the mode in which they are administered.
Bioavailability is used as a reflection of the absorption of the medicine. For instance, in intravenous medication, the drug gets into the circulatory system instantly. The bioavailability of such drugs is said to be 100%.
The concept of bioavailability is more important in oral medication. In the case of oral drugs, they first have to navigate the acidity in the stomach and get absorbed by the digestive system.
Enzymes in the digestive system begin the metabolization process of the drugs. This process reduces the number of drugs that will get into the circulatory system. After absorption into the gut, oral medications will have to go through first-pass metabolism.
After administration, oral drugs are processed in large amounts by the gut wall, liver, and digestive enzymes. This lowers the amount of the drug that gets into the circulation system and will have a low bioavailability.
Other drug administration methods that lower the bioavailability is transdermal and intramuscular.
- Distribution – this is the process by which drugs administered spread to all the parts of the body. Distribution varies depending on the physiology of the person on medication and the biochemical properties of the drug being administered. The process of drug distribution in pharmacokinetics is influenced by convection and diffusion.
Diffusion and convection are further influenced by the size, binding abilities of the drug, polarity, the body of the patient, or the fluid status of the patient. The purpose of distribution is to achieve effective drug concentration. Medication can only be effective if reaches the designated compartmental destination, not protein-bound, and the volume of the drug is distributed.
The volume of distribution – this is the method used to describe the distribution of a drug. The volume of distribution can be defined as the number of drugs in the body divided by drug concentration in the plasma.
It is important to understand the volume of distribution for health practitioners to understand dosage schemes.
Protein building – once in the body, a drug can be protein-bound or not. Protein-free drugs are the only drugs that can act in their pharmacologically active sites such as receptors. Less protein binding increases the number of available drugs to act on receptors. This leads to greater drug effects and increased chances of toxicity.
Proteins that bind drugs are alpha-acid glycoprotein and albumin. The two proteins fluctuate depending on the age and development of the patient, their nutrition status, and if they have any other underlying kidney or liver disease.
Protein binding is relevant in cases of renal failure. In this case, uremia lowers the ability of acidic drugs to bind serum proteins. This increases the drug effect thereby increasing chances of toxicity such as respiratory depression.
- Metabolism – this is the process in which drugs are processed by the body. They are processed into their subsequent compounds. Metabolism helps convert drugs into substances that can dissolve more in water and progress to renal excretion. In some cases, metabolism converts drugs into active metabolites.
Metabolism strategies occur in different areas of the body. They occur in the gastrointestinal tract, plasma, skin, lungs, and kidneys. A larger amount of metabolism occurs in the liver.
- Excretion – this is the process by which ingested drugs are eliminated from the body. A lot of excretion occurs in the kidneys. However, certain drugs are excreted in the lungs, gastrointestinal tract, and skin. In kidneys, drugs are usually excreted by passive filtration in secretion in the tubules or glomerulus.
Clearance – Clearance is the ratio of the excretion rate of a drug to the drug concentration in plasma. The clearance of a drug is influenced by blood flow, the drug, and the status of the organs of the patient.
In perfect organs, medication is completely cleared from the blood. Practitioners should understand clearance to appropriately calculate dosing rates of medications.
Half-life – the half-life is the amount of time needed for serum drug concentration to reduce by 50%.
Drug Kinetics – drug kinetics is the graphical manifestation of drug metabolism and excretion. Drug kinetics illustrates the half-life of medication. There are two major forms of drug kinetics. They are described by first-order and zero-order kinetics.
Zero-order kinetics usually show a constant rate of metabolism and elimination that is independent of drug concentration. A good example of zero-order kinetics is phenytoin and alcohol elimination.
First-order kinetics depends on the amount of plasma concentration of the drug. First-order kinetics is the major model of elimination for most medications. Kinetic models are used to estimate steady states and bring the elimination of drugs to completion.
Steady-state occurs when drug administration and its elimination are balanced. This creates a plasma concentration that does not change with time. Under ideal circumstances, a steady state is achieved after treatment of the patient has been going on for four to five half-lives.
Clinical significance of Pharmacokinetics
Health providers prescribe medications with the aim of a therapeutic outcome while they minimize adverse side effects. Proper understanding of pharmacokinetics is important in establishing treatment plans that involve medications.
Pharmacokinetics seeks to summarize the movement of drugs in the body as well as the actions of the body on drugs. The theories, equations, and terms used in pharmacokinetics help health practitioners to estimate better the locations and concentrations of drugs in the different areas of the body.
Drug concentration is required to obtain desired effect and amount for a higher chance of adverse reactions that are determined through laboratory testing. Through pharmacokinetics, health providers have an easy time estimating dosing for safe medication over some time. Additionally, they can estimate the time it will take for medication to completely leave the body of the patient.
However, these estimations can be influenced by drug dosage differences and the pathophysiology of the patient. Understanding these concepts is important for medical practitioners. It helps them to improvise when faced with a clinical situation that needs improvisation.
Interventions of Nurses, Allied Health and Interprofessional Team
Interprofessional members need to work together to promote the safety and efficacy of pharmacotherapy. Patients should be trained on correct self-administration of drugs and how to store them well. They can be educated by nurses, pharmacists, or physicians. Getting this information from multiple providers gives the patient the assurance they need.
In addition, the team of interprofessional needs to monitor signs of drug toxicity and efficacy, which are influenced by the pharmacokinetic parameters of drugs. Pharmacists should always crosscheck the dosing, perform a drug interaction check and adhere to the plasma concentrations of drugs if ii is clinically warranted.
Pharmacists and nurses should establish an open communication line with the physician prescribing the medicine so that they discuss or report any concerns they may have on the patient’s drug regimen and regarding drug therapy. Interprofessional communication is important to optimize patient outcomes with few adverse effects.
Pharmacokinetics is an important area of study for healthcare providers. It guides them in prescribing medication and treatment. Pharmacokinetics helps us understand how drugs get into our body, how they move around in the body until they are excreted.