Department Of Pharmacy

BIOPHARMACEUTICS

PLASMA DRUG CONCENTRATION TIME CURVE

Submitted To:SIR MOOSA RAZASubmitted By:ZAIN HANIF BPD-01093-263NABEELA ANWAR BPD-01101-007 IFRA EHSAN BPD-01101-025 HINA ZAINAB BPD-01101-028 SEHAR ANJUM BPD-01101-035 SALWA NAEEM BUTT BPD-01101-073 (Section 7th A)PLASMA DRUG CONCENTRATION TIME CURVE GRAPHThe plasma drug concentration-time curve graph is generated by obtaining the drug concentration in plasma samples taken at various intervals after the drug product is administrated.

GRAPHThe concentration of drug (mg/ml) in each plasma sample is plotted against time (hr.) at which the plasma sample was removed.

Plasma Drug concentration = X-axisTime = Y-axis

PURPOSEIt is a way to determine: MEC (Minimum effective Concentration) MTC (Minimum toxic Concentration) Systemic drug bioavailability Duration of Action

PHARMACOLOGIC PARAMETERSThe relationship of the drug level-time curve and various pharmacologic parameters for the drug are:

MEC: abbreviation forMinimum Effective ConcentrationIt is the Minimum concentration of drug needed at the receptors to produce the desired pharmacologic effect.For some drugs, such as those acting on autonomic nervous system, it is useful to know the concentration of drug that will just barely produce a pharmacologic effect.MTC: abbreviation forMinimum Toxic ConcentrationIt is the concentration needed to just barely produce a toxic effect.ONSET TIME: It is the time required by the drug to reach the MEC

TERMINATION TIME:It is time for the drug to decline back to the MEC.

DURATION OF ACTION: It is the difference between the Onset time and the termination time.It is also defined as the time at which the drug remains above the MEC.

THERAPEUTIC WINDOW: It is the concentration between the MEC and MTC.Drugs with the wide therapeutic window are generally considered safer than drugs with narrow therapeutic window.

PHARMACOKINETIC TERMS: Peak plasma levelAUC (Area under Curve)

Peak plasma level:It is the maximum drug concentration in the plasma and is a rough marker of average rate of drug absorption.tmax: It is the time of Peak plasma concentrationThe time required to reach maximum drug concentration after drug administration.At tmax Peak plasma drug absorption occurs and the rate of drug absorption exactly equals to rate of drug elimination. The value for tmax will be smaller as the absorption rate for the drug becomes more rapid. (Indicating less time required to reach peak plasma concentration)UNIT: Units for tmax are units of time (e.g. hours, minutes)Cmax: It is the Peak plasma drug concentrationIt represents the maximum plasma drug concentration obtained after oral administration of drug.UNIT: units for Cmax are concentration units (e.g. mg/ml, ng/ml)

AUC: Area Under Plasma level-time curve:AUC is related to the amount of drug absorbed systemically. It is a measurement of the extent of drug bioavailability. For many drugs AUC is directly proportional to the dose.

Difference between PLTC of extravascular and vascular administration:Vascular administration has no absorption phase.

Factors affecting Plasma Concentration Time Curve:

Gastric emptying time Intestinal Transit Time Gastrointestinal Abnormality / Pathology Gastric Content Gastrointestinal pH Drug metabolism (first pass effect)

REFRENCE: Applied Bio-pharmaceutics & Pharmacokinetics (6th edition) by Leon Shargel.