What is the context sensitive half life of remifentanil?
The context sensitive half-life for remifentanil is 3.2 minutes and is independent of the duration of the infusion conversely to all other u-agonists . In comparison, after a 3-hour infusion of alfentanil, the context-sensitive half-life was found to be 47.3 minutes.
Is half-time the same as half-life?
–> i.e. Elimination half-time is essentially halflife after the initial rapid redistribution phase, and is not about elimination at all.
What is the context sensitive half-time of propofol?
Half-life: Propofol is bi-phasic, with its initial half-life being relatively quick, around 40 minutes, and its terminal half-life usually being 4 to 7 hours. Context-sensitive half-time may be up to 1 to 3 days after a 10-day infusion. The clinical effect of propofol is much shorter in duration.
What is the half-life of anesthesia?
The initial distribution half-life is 2–8 min and elimination half-life is 4–7 h. The longer elimination half-life is indicative of distribution to fatty tissues with low perfusion, which results in a slow return of propofol to the central compartment.
Which opioid has the shortest half-life?
In anesthesiology, there has been similar fashion in opioid use, with the most variable element being the elimination half-life – ranging from ultra-short (remifentanil) to ultra-long (methadone). Nominally, the former is 0.6 hr, while that of the latter is 24–36 hr.
What is terminal half-life of drugs?
Terminal half-life is the time required for the plasma concentration to fall by 50% during the terminal phase, and not the time required to eliminate half the administered dose.
What is the difference between half-life and duration?
The duration is the time period and the half-life of a radioactive substance is the duration for half of the atomic nuclei of the radioactive sample of the substance to decay.
What is the relationship between half-life and time constant?
The half-life of a reaction is the time required for the reactant concentration to decrease to one-half its initial value. The half-life of a first-order reaction is a constant that is related to the rate constant for the reaction: t1/2 = 0.693/k.
What is context sensitive decrement time?
Definition. The context-sensitive half-time is the time required for blood or plasma concentrations of a drug to decrease by 50% after discontinuation of drug administration.
Why Propofol is white in Colour?
Newer generic formulations contain sodium metabisulfite or benzyl alcohol as antimicrobial agents. Propofol emulsion is a highly opaque white fluid due to the scattering of light from the tiny (about 150-nm) oil droplets it contains: Tyndall Effect.
What is half-life pharmacokinetics?
The duration of action of a drug is known as its half life. This is the period of time required for the concentration or amount of drug in the body to be reduced by one-half. We usually consider the half life of a drug in relation to the amount of the drug in plasma.
Why is a short half-life beneficial?
Some radioisotopes used in nuclear medicine have short half-lives, which means they decay quickly and are suitable for diagnostic purposes; others with longer half-lives take more time to decay, which makes them suitable for therapeutic purposes.
Which opioid has the fastest onset of action?
Fentanyl is a synthetic opioid that is up to 80 times more potent than morphine. Fentanyl is highly lipid soluble and has a rapid onset of action due to fast tissue uptake.
What is the difference between terminal half life and elimination half-life?
Following i.v. administration, the terminal half-life is the time required for plasma/blood concentration to decrease by 50% after pseudo-equilibrium of distribution has been reached; then, terminal half-life is computed when the decrease in drug plasma concentration is due only to drug elimination, and the term ‘ …
What is the difference between plasma half-life and biological half life?
In a medical context, half-life explicitly describes the time it takes for the blood plasma concentration of a substance to halve (plasma half-life) its steady-state when circulating in the full blood of an organism….Common prescription medications.
Why is half-life important?
Understanding the concept of half-life is useful for determining excretion rates as well as steady-state concentrations for any specific drug. Different drugs have different half-lives; however, they all follow this rule: after one half-life has passed, 50% of the initial drug amount is removed from the body.
What does 5 half-lives mean?
The half-life can also be a guide for how long a drug will take to reach a stable level in your body when you first start taking it. Generally, it will take about five times the drug’s half-life to build a stable level in your body.
Is the relationship between half-life and time dependent or independent?
The half-life of a reaction is the time required for a reactant to reach one-half its initial concentration or pressure. For a first-order reaction, the half-life is independent of concentration and constant over time.
Is half-life time constant?
The half-life of a reaction is the time required for the reactant concentration to decrease to one-half its initial value. The half-life of a first-order reaction is a constant that is related to the rate constant for the reaction: t1/2 = 0.693/k. Radioactive decay reactions are first-order reactions.
What is decrement time?
In the Diprifusor, a ‘decrement time’ is displayed that is the calculated time it would take plasma propofol to fall to a predetermined concentration at which the patient should be awake.