Pharmokentics and dynamics maths Flashcards
Define the terms pharmacokinetics, ADME and pharmacodynamics
Pharmacokinetics:
Pharmacokinetics refers to the study of how the body interacts with a drug. It encompasses the processes of absorption, distribution, metabolism, and excretion (ADME) of a drug within the body. Pharmacokinetics helps determine how a drug is absorbed into the bloodstream, distributed to various tissues, metabolized (chemically transformed), and eliminated from the body. Understanding pharmacokinetics is crucial for determining the optimal dosage, dosing frequency, and duration of drug therapy.
Pharmacodynamics refers to the study of how a drug interacts with the body to produce its therapeutic or toxic effects. It focuses on the relationship between drug concentration at the site of action and the resulting biological response. Pharmacodynamics involves studying the drug’s mechanism of action, its effects on specific receptors or cellular targets, and the physiological or biochemical changes it induces. Understanding pharmacodynamics is essential for optimizing drug therapy, predicting drug efficacy, and managing adverse drug reactions.
Define the terms – clearance, half-life, rate of elimination, bioavailability.
Clearance refers to the rate at which a drug is eliminated from the body or removed from the systemic circulation. It represents the volume of plasma cleared of a drug per unit of time. Clearance is a pharmacokinetic parameter that takes into account the combined processes of metabolism and excretion that remove the drug from the body. Clearance is typically expressed as a volume per unit time, such as milliliters per minute (mL/min) or liters per hour (L/hr).
Half-life is the time it takes for the concentration of a drug in the body to reduce by half.
The rate of elimination refers to the speed at which a drug is removed from the body. It represents the amount of drug eliminated per unit of time.
Bioavailability is a measure of the fraction or percentage of an administered drug dose that reaches the systemic circulation and is available to exert its pharmacological effects. It represents the extent and rate at which a drug is absorbed and becomes available at the site of action.
Understand difference in kinetics between IV bolus, IV infusion and oral administration.
IV Bolus Administration:
IV bolus administration involves delivering a drug directly into the systemic circulation through a rapid injection into a vein. With IV bolus administration, the entire drug dose is administered all at once. Key characteristics include:
Absorption: The drug is immediately and completely available in the bloodstream. Absorption is instant and bypasses the absorption phase observed with oral administration.
Onset of Action: The drug rapidly reaches its peak concentration in the bloodstream, resulting in a quick onset of action.
IV infusion involves administering a drug gradually over a specific period by continuously infusing a solution containing the drug into a vein. Key characteristics include:
Absorption: The drug is directly introduced into the bloodstream, resulting in rapid and complete availability.
Onset of Action: The drug concentration in the bloodstream gradually increases as the infusion progresses, leading to a delayed onset of action compared to IV bolus administration.
Duration of Action: The duration of action can be extended by adjusting the infusion rate and duration.
Oral Administration:
Oral administration involves swallowing a drug in the form of a tablet, capsule, or liquid, which is then absorbed through the gastrointestinal tract. Key characteristics include:
Absorption: The drug undergoes absorption through the gastrointestinal tract, which can be influenced by factors such as the drug’s solubility, stability, and interactions with food or other medications.
Onset of Action: The drug is typically absorbed more slowly compared to IV administration, resulting in a delayed onset of action.
Duration of Action: The duration of action can vary depending on the drug’s pharmacokinetic properties, metabolism, and elimination. It may be longer compared to IV administration, especially for sustained-release formulations.
