Flip-flop kinetics
Encyclopedia
In pharmacokinetics
, flip-flop
phenomenon happens when a drug is released at a sustained rate instead of immediate release, such as sustained-release formulation v.s. immediate-release formulation (tablet
, IV
).
In flip-flop kinetics, ka (absorption constant) is much slower than ke (elimination constant). This apparent difference shift the slope of logCp vs time curve in which now the apparent part of ke looks much smaller than it is if the drug is administered intravenously or by immediate-release formulation. The part of downward curve becomes a reflection of actual ka while the upward part of the curve is the actual representation of ke. That "flip-flop" part of curve is the so-called flip-flop kinetics.
The application of flip-flop kinetics is very important in the development of sustained-release and controlled-release formulation in pharmaceutical manufacturing.
Pharmacokinetics
Pharmacokinetics, sometimes abbreviated as PK, is a branch of pharmacology dedicated to the determination of the fate of substances administered externally to a living organism...
, flip-flop
Flip-flop
Flip-flops, thongs, Japanese sandals, or jandals are an open type of outdoor footwear, consisting of a flat sole held loosely on the foot by a Y-shaped strap, like a thin thong, that passes between the first and second toes and around either side of the foot...
phenomenon happens when a drug is released at a sustained rate instead of immediate release, such as sustained-release formulation v.s. immediate-release formulation (tablet
Tablet
A tablet is a pharmaceutical dosage form. It comprises a mixture of active substances and excipients, usually in powder form, pressed or compacted from a powder into a solid dose...
, IV
Intravenous therapy
Intravenous therapy or IV therapy is the infusion of liquid substances directly into a vein. The word intravenous simply means "within a vein". Therapies administered intravenously are often called specialty pharmaceuticals...
).
In flip-flop kinetics, ka (absorption constant) is much slower than ke (elimination constant). This apparent difference shift the slope of logCp vs time curve in which now the apparent part of ke looks much smaller than it is if the drug is administered intravenously or by immediate-release formulation. The part of downward curve becomes a reflection of actual ka while the upward part of the curve is the actual representation of ke. That "flip-flop" part of curve is the so-called flip-flop kinetics.
The application of flip-flop kinetics is very important in the development of sustained-release and controlled-release formulation in pharmaceutical manufacturing.