- How is a drug distributed in the various body compartments?
- What are the factors that affect distribution?
- Does food affect drug absorption?
- How does pH affect drug distribution?
- How does blood flow affect drug distribution?
- What does it mean for a drug to be ionized?
- How do you tell if a drug is acidic or basic?
- How do drugs get absorbed into the body?
- How does gastric emptying rate affect drug absorption?
- How does body fat affect drug distribution?
- What organ is responsible for drug metabolism?
- How does lipid solubility affect drug distribution?
- What factors affect distribution of a drug?
- What is drug absorption?
How is a drug distributed in the various body compartments?
The extent of drug distribution into tissues depends on the degree of plasma protein and tissue binding.
In the bloodstream, drugs are transported partly in solution as free (unbound) drug and partly reversibly bound to blood components (eg, plasma proteins, blood cells)..
What are the factors that affect distribution?
Factors affecting distributionclimatic factors consist of sunlight, atmosphere, humidity, temperature, and salinity;edaphic factors are abiotic factors regarding soil, such as the coarseness of soil, local geology, soil pH, and aeration; and.social factors include land use and water availability.
Does food affect drug absorption?
Like food, drugs taken by mouth must be absorbed through the lining of the stomach or the small intestine. Consequently, the presence of food in the digestive tract may reduce absorption of a drug. Often, such interactions can be avoided by taking the drug 1 hour before or 2 hours after eating.
How does pH affect drug distribution?
It is known that mucosal lining of GIT is impermeable to the ionized form of weak acids or bases. Most of the drugs are available as weak acids or weak bases. The weak base is absorbed at a faster rate from the intestine (pH 7.50 – 8), this is because the basic substances can’t be ionized in basic medium.
How does blood flow affect drug distribution?
After a drug enters the systemic circulation, it is distributed to the body’s tissues. Distribution is generally uneven because of differences in blood perfusion, tissue binding (eg, because of lipid content), regional pH, and permeability of cell membranes.
What does it mean for a drug to be ionized?
Ionized (or charged) drugs are not absorbed as efficiently as un-ionized drugs are. Practically speaking, this means that if taken orally, a drug that is a weak acid will be absorbed primarily in the acidic environment; whereas, a drug that is a weak base will be absorbed in the alkaline environment small intestines.
How do you tell if a drug is acidic or basic?
Amines, for example, are basic and have pKa values of approximately 9, while phenols are acidic and typically have pKa values of around 10. The only sure way to know whether a drug is acidic or basic is to learn the functional groups that confer acidity and basicity on a molecule.
How do drugs get absorbed into the body?
Medicines taken by mouth are shuttled via a special blood vessel leading from the digestive tract to the liver, where a large amount of the medicine is broken down. Other routes of drug administration bypass the liver, entering the bloodstream directly or via the skin or lungs.
How does gastric emptying rate affect drug absorption?
In most instances, increasing the rate of gastric emptying and gastro-intestinal motility increases the rate of absorption of a drug but, for digoxin and riboflavin, increased gastrointestinal motility is associated with a decrease in the rate of absorption.
How does body fat affect drug distribution?
In obese individuals, blood flow to fat is even poorer. Obese individuals are also likely to have a degree of heart failure which further decreases blood flow. This makes their fat a large compartment of potential distribution for lipophilic drugs which fills gradually, and then becomes a slowly emptying reservoir.
What organ is responsible for drug metabolism?
Excretion involves elimination of the drug from the body, for example, in the urine or bile. Most drugs must pass through the liver, which is the primary site for drug metabolism. Once in the liver, enzymes convert prodrugs to active metabolites or convert active drugs to inactive forms.
How does lipid solubility affect drug distribution?
Drug absorption depends on the lipid solubility of the drug, its formulation and the route of administration. A drug needs to be lipid soluble to penetrate membranes unless there is an active transport system or it is so small that it can pass through the aqueous channels in the membrane.
What factors affect distribution of a drug?
The drug distribution is usually varied, and depends on several factors such as:Blood perfusion.Tissue binding (since drug binding is linked to the lipid content)Regional pH.Cell membrane permeability.
What is drug absorption?
Drug absorption is the movement of a drug into the bloodstream after administration. Absorption affects bioavailability—how quickly and how much of a drug reaches its intended target (site) of action. Factors that affect absorption (and therefore bioavailability) include.