What are the factors affecting absorption of drug?
Absorption: depends on drug pKa and whether its an acidic or basic drug, GI ph influences drug absorption by determining amount of drug that would exist in unionised form at the site of absorption.
How does absorption affect bioavailability?
Absorption is the movement of drug from the site of drug administration to the systemic circulation. Bioavailability is the extent to which absorption occurs. In other words, bioavailability is the fraction of the administered drug that reaches the systemic circulation in the unchanged form.
What are the factors affecting drug action?
Factors influencing drug effects
- Type of drug.
- Quantity of drug used.
- Method of drug use.
- Time taken to consume.
- Tolerance.
- Gender, size and amount of muscle.
- Use of other psycho-active drugs.
- Mood or attitude.
What are the factors affecting bioavailability?
Factors Affecting Bioavailability
- Absorption.
- Food Effect.
- Drug metabolism/ biotransformation.
- Energy dependent efflux transporters.
- Physico-chemical factors.
- First pass metabolism.
- CYP450 isozymes.
How does drug concentration affect absorption?
The most common mechanism of absorption for drugs is passive diffusion. This process can be explained through the Fick law of diffusion, in which the drug molecule moves according to the concentration gradient from a higher drug concentration to a lower concentration until equilibrium is reached.
What are the factors influencing drug action?
The effect of any drug on an individual is the result of three interacting factors: the drug itself. the individual user. the environment in which drug use occurs.
How is the bioavailability of a medication affected by the route of administration?
By definition, when a medication is administered intravenously, its bioavailability is 100%. However, when a medication is administered via routes other than intravenous, its bioavailability is generally lower than that of intravenous due to intestinal endothelium absorption and first-pass metabolism.
What are the factors that affect drug distribution?
Several factors impact drug distribution. These factors include the concentration of drug transporters in blood, pH, perfusion, body water composition, body fat composition, and most certainly disease conditions (e.g., volume depletion, burns, third spacing).
What are the barriers to drug distribution?
These barriers may be composed of endothelial (e.g., blood–brain barrier) or epithelial cells (e.g., placental), or combinations of those cells working in concert to form a significant obstacle to drug passage into selective organs or tissues.
What are different barriers in drug distribution?
Active efflux transporters also exist in the placenta, analogous to the gut and blood-brain barrier. These are Pgp, multidrug resistance–associated protein (MRP), and breast cancer resistance protein (BCRP). These transport proteins are located in many tissues but also appear to be expressed in the placenta.
What are the factors that affect drug absorption?
FACTORS AFFECTING DRUG ABSORPTION. List of content :– I.PHARMACEUTICAL FACTORS A] Chemical factors B] Physicochemical properties of drug substances. 1.drug solubility & dissolution rate 2. Particles size & effective surface area 3. Polymorphism & amorphism 4. Solvates & hydrates 5.salt form of drug 6.
What is the role of pH in the absorption of drugs?
—Which increases the pH of the diffusion layer, which promotes the solubility and dissolution of a weak acid and absorption is bound to be rapid. Reverse in the case of salts of weak bases, it lowers the pH of diffusion layer and the promoted the absorption of basic drugs.
What are the factors affecting the bioavailability of a drug?
Presystemic metabolism: The main reason for the decrease in bioavailability of a drug are decreased absorbtion or first pass metabolism. various enzyme that affect presystemic meatbolism of drugs are : -gutwall enzyme -hepatic enzyme -bacterial enzyme. 12 13. 2)Physicochemical factors: • DRUG SOLUBILITY & DISSOLUTION RATE.
How does Intestinal Resection affect the absorption of drugs?
Intestinal resection decreases the surface area leading to a decreased absorption. Similarly, when the topically acting drugs are applied on a large surface area, they are better absorbed. Organophosphate compounds are highly lipid soluble and poisoning can occur even by absorption through skin.