What is distribution and elimination phase?
The early rapid decline is due to distribution to the tissue compartment, and hence this early period is called the distribution phase. Conversely, the slower decline at later times is due to drug elimination, and hence this later period is called the elimination phase.
What is alpha and beta half-life?
Two half-lives can be described: the alpha half-life, the rate of decline in plasma concentrations due to the process of drug redistribution from the central to the peripheral compartment, and the beta half-life, the rate of decline due to the process of drug elimination due to metabolism.
How many half-lives does it normally take to remove 95% of a drug from the body?
Even further, 94 to 97% of a drug will have been eliminated after 4 to 5 half-lives. Thus, it follows that after 4 to 5 half-lives, the plasma concentrations of a given drug will be below a clinically relevant concentration and thus will be considered eliminated.
How does volume of distribution affect half-life?
Half-life is dependent on both clearance and volume of distribution, such that a decrease in clearance, as might be seen with a CYP1A2 or CYP2C19 substrate, or an increase in volume of distribution will prolong the half-life and lead to a longer dosage interval.
What is the relationship between volume of distribution and elimination?
Abstract 0 A relationship between drug distribution and elimina- tion in multicompartment systems has been demonstrated, which suggests that under certain conditions a decrease in the elimination rate constant (keJ results in a significant decrease in the apparent volume of distribution.
What does half-life of 12 hours mean?
3 This means that if you begin taking a medication with a half-life of 24 hours, after four days, or on the fifth day, the rate of intake of the drug will approximately equal the rate of elimination. If the half-life is 12 hours, you’ll reach a steady state at the beginning of the third day (after 48 hours).
What does high volume of distribution mean?
The larger the volume of distribution, the more likely that the drug is found in the tissues of the body. The smaller the volume of distribution, the more likely that the drug is confined to the circulatory system.
Why is volume of distribution important?
The volume of distribution is useful in estimating the dose required to achieve a given plasma concentration as A = C ·Vd, with A = amount of drug in the body ( ≈ dose, shortly after administration) and C = plasma concentration. Variation of Vd mainly affects the peak plasma concentration of the drug.
What is terminal elimination?
This is used to measure the removal of things such as metabolites, drugs, and signalling molecules from the body.
What is the difference between alpha and beta elimination reaction?
Alpha and beta elimination are two types of organic chemical reactions. The key difference between alpha and beta elimination reaction is that in alpha elimination reaction, two leaving groups leave from the same atom whereas, in beta elimination reaction, the two leaving groups leave from two adjacent atoms of the same molecule.
What is the difference between alpha and beta half life?
Most of the drugs have alpha half life and remain in the plasma. Drugs having beta half life have two half lives, one in the plasma and one in the tissues. They are highly distributed drugs. Their total time of elimination is more. When the drug is absorbed and reaches the plasma, it is distributed to the tissues.
Can the beta distribution have values less than 1?
But the beta distribution can have values less than 1 (any non-negative number). At the extreme case, α = β = 0 yields a bimodal PDF (probability density function) with values at only 0 and 1.
What is the product of an alpha elimination reaction?
Elimination occurs at this one carbon atom; leaving groups are hydrogen atom and one chlorine atom. Similarly, formic acid also can undergo alpha elimination. The stable products of this elimination reaction include water and carbon monoxide in the presence of an acidic condition.