UNIT 2 (BIOPHARMACEUTICALSㅡFATE OF DRUG) Flashcards
• the study of the physicochemical properties of the drug and the drug product, in vitro, on the bioavailability of the drug, in vivo, to produce a desired therapeutic effect.
BIOPHARMCEUTICS
- It is the study of the kinetics of absorption, distribution, metabolism, and excretion (ADME) of drugs and their corresponding pharmacologic, therapeutic, or toxic effects in animals and man.
PHARMACOKINETICS
• The absorption process is driven by the concentration gradient across the membrane, with the passage of drug molecules occurring primarily from the side of high concentration.
Described by _____________
• Fick’s first law of Diffusion
• involves the aqueous channels or pores through which hydrophilic drugs can pass.
○ Occurs in the jejunum and proximal tubules of kidneys
○ Absent in the stomach and the lining of the urinary bladder
Filtration
• Drugs are better absorbed in __________ form.
unionized
• This type of transport is thought to involve membrane components that may be enzymes or some other type of agent capable of forming a complex with the drug (or other agent) at the surface membrane.
SPECIALIZED TRANSPORT MECHANISM
• Under normal circumstances, a drug may be expected to remain in the stomach for 2 to 4 hours (_________________) and in the small intestine for 4 to 10 hours
• The gastric emptying time for a drug is most rapid with a fasting stomach, becoming slower as the food content is increased.
gastric emptying time
• ↑ increase GET
▪ High fat /fatty foods
▪ Cold food
▪ Gastric ulcers
▪ Stress
▪ Vigorous exercise
▪ Lying on the left side
▪ Drugs (Antidiarrheal
/antimotility agents)
▪ Hunger
• ↓ decrease GET
▪ Spicy foods
▪ Extreme temp. of meal
▪ Gastrectomy
▪ Depression
▪ Mild Exercise
▪ Lying on right side
▪ Motility enhancing agents:
(metoclopramide, domperidone, cisapride)
▪ Diabetes Mellitus
- They form a subtype of solid solvates in which water molecules are incorporated into the crystal lattice of a compound
o The possibility of solid APIs to exist at different levels of hydration represents another way to improve the APIs’ properties by altering their solid state structures.
● Hydrates
● The drug–protein complex-
● reversible,
● involves albumin (globulins also participate in the binding of drugs, particularly some of the hormones)
● Entails formation of relatively weak bonds (van del Waals, hydrogen, ionic)
● Binding capacity is saturable
Protein-binding
o NOT exposed to the body’s detoxification (metabolism) processes
o NOT filtered through the renal glomeruli
BOUND DRUG
o Serves as a reservoir or depot (only released when the level of free drug in the blood is no longer adequate to ensure protein saturation)
INACTIVE PORTION
● the major process by which foreign substances, including drugs, are eliminated from the body
● Biotransformation indicates the chemical changes to drugs within the body as they are metabolized and altered by various biochemical mechanisms.
Metabolism
▪ an inactive parent compound, may be converted to an active therapeutic agent by chemical transformation in the body.
Prodrugs