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VetMed Pharmacology

VetMed Pharmacology - Absorption

QuestionAnswer
External Tissue and Organ Barriers Limiting Absorption cutaneous/dermal structures GI mucosal epithelium Pulmonary epithelium Mucosal membranes Corneal epithelium
Internal Tissue and Organ Barriers Limiting Absorption SQ tissues Musculature Capillary basement membrane Vascular endothelium
Advantages of PO Route of Administration Safest Large V and doses can be absorbed Convenient, Economical SA of SI allows adequate absorption of weak-acid or weak-base compounds
Disadvantages of PO Route of Administration Variable rate of absorption Lower bioavailability Can be affected by diet GI irritation possible Caustic environment may inactivate some pharmaceuticals "First pass" removal by liver (Lidocaine)
Advantages of IV Route of Administration Rapid onset 100% bioavailability
Disadvantages of IV Route of Administration Least safe form of delivery
Advantages of IM Route of Administration Timed release Safer than IV
Disadvantages of IM Route of Administration Slow absorption with dehydration Abscess formation
Advantages of SQ Route of Administration Low risk Timed release
Disadvantages of SQ Route of Administration Slowed absorption with dehydration
Advantages of IP Route of Administration Potentially can give large volume
Disadvantages of IP Route of Administration Technically difficult Organ damage possible
Advantages of IO Route of Administration Accessible route even with severe dehydration
Disadvantages of IO Route of Administration Technically difficult Painful
Advantages of ID Route of Administration Relatively safe
Disadvantages of ID Route of Administration Relatively slow absorption rate Administration volume is limited
Nebulization a technique for physically converting a liquid preparation into fine "mist" with droplets of small enough size to pass to the level of the alveolus
Biological Variables that Influence Pharmaceutical Absorption surface area available biological mechanisms (passive vs. active transport) environmental pH differences vascular density biological barrier composition (muscle vs. skin) tissue binding
Pharmaceutical Variables that Influence Absorption concentrations molecular size lipid solubility molecular shape ionic charge
Mechanisms of Pharmaceutical Biotransport membrane pores active transport facilitated diffusion ionic or electrochemical diffusion pinocytosis/phagocytosis passive diffusion
Active Transport energy-dependent transferred from low to high concentration can become saturated
Membrane Pores movement between cells dependent on hydrostatic pressure
Facilitated Diffusion carrier-dependent no energy needed transferred from high to low concentration can be saturated can be inhibited by metabolic poisoning agents (glucose entry)
Ionic or Electrochemical Diffusion dependent on electrochemical gradient across membrane driven by difference in ionic charge depolarization costs energy to maintain high to low gradient
Pinocytosis and Phagocytosis active process requiring energy engulfing of a volume of fluid or of particulate matter minor transport processes
Simple Passive Diffusion no energy required transferred from high to low concentration most common and most important in-vivo transport process cannot be saturated rate and transport dependent on concentration of pharmaceutical
The rate at which a compound traverses the distance from point A to point B... ...is a function of the square of that distance.
Anatomical Variables of Absorption into IV Compartment degree of capillary density tissue mass portion of the total cardiac output received
Calculating Bioavailability AUC (IM) / AUC (IV) X 100
Fick's First Law of Diffusion a substance will diffuse through an area at a rate that is dependent upon the differences in concentration for a given substances between two given points
Anatomical Structures with Membranes of Greater Thickness blood brain barrier blood-CSF barrier blood-milk (mammary) barrier placental barrier
Relationship of Diffusion and Molecular Size rate of diffusion is inversely proportional to square root of molecular weight, and for large compounds is inversely proportional to third square root of molecular weight
How to Increase Aqueous Solubility addition or formulation with salts (Na+, K+) incorporate a charged "solvent" decrease overall size (mass) change the crystalline shape
Oil:Water Coefficient a measure or indicator for estimating how well a pharmaceutical will diffuse across an intact phospholipid bilayer of cell membranes
How to Increase Lipid Solubility increase pharmaceutical alkylation increase level of phenyl group addition or substitution replacement of oxygen groups with sulfur groups increase halogen group substitutions or additions decrease or minimize +/- of ionized charged groups
Variables Influencing Diffusion of Pharm Preparations in the form of a Suspension depot surface area depot drug concentration particle surface area dissolution rate injection volume viscosity
Donnan Effect charged molecules on one sie of a semi-permeable membrane will alter concentrations of "permeable" ionized particles
Ways to Manipulate Pharmaceutical Absorption manipulation of size, shape, and ionic charge encapsulation use of suspending agents use of vasoconstrictive agents dispersion or "spreading" agents
Pharmocokinetic Definition of Absorption transport or diffusion of a pharmaceutical or toxin from the anatomical site of administration into the central (intravascular) compartment
Definition of Bioavailability percent of the original dose administered that enters the central (intravascular) compartment
Created by: 26509889