Plasma Drug Concentration-Time Curve

Study Notes

Relationship Between Drug Absorption and Elimination

The rate of drug absorption affects the time it takes for a drug to reach its peak plasma concentration.
Faster absorption can lead to quicker onset of action, while slower absorption may prolong drug effects.
Drug elimination occurs simultaneously, influenced by factors like metabolism and excretion which determine the duration of a drug's action.

Purpose of Plasma Drug Concentration-Time Curve

Illustrates the relationship between drug concentration in plasma and time after administration.
Helps in understanding pharmacokinetics, including absorption, distribution, metabolism, and elimination.
Assists in determining appropriate dosing schedules and monitoring therapeutic levels.

Main Mechanisms of Drug Elimination

Renal excretion: Primary route via urine, filtering drugs from blood.
Hepatic metabolism: Liver processes drugs, converting them to metabolites for excretion.
Biliary excretion: Some drugs are eliminated through bile into the intestines.
Lung excretion: Volatile drugs can be exhaled through respiration.

Significance of Minimum Effective Concentration (MEC)

MEC is the lowest concentration of a drug in plasma required to produce a therapeutic effect.
Ensures that drugs administered are effective in achieving desired outcomes.
Helps in establishing the minimum amount necessary to avoid therapeutic failure.

MEC and Tissue Concentration Relationship

MEC provides a benchmark to assess drug levels in tissues, ensuring they exceed this concentration for efficacy.
Tissues may accumulate drugs, necessitating a clear understanding of both plasma and tissue concentration dynamics for effective therapy.

Purpose of Minimum Toxic Concentration (MTC)

MTC defines the threshold above which drug levels may cause adverse effects or toxicity.
Vital for ensuring that dosages remain below this level to prevent harmful reactions.
Aids in balancing therapeutic effects with safety profiles in drug administration.

Description

Learn about how the plasma drug concentration-time curve is generated by plotting the drug concentration in plasma samples against time intervals after drug administration. Understand how drug concentrations rise in the bloodstream up to a maximum level as the drug reaches the systemic circulation.