BIOL 1550 Lecture Notes - Lecture 2: Weak Base, Extracellular Fluid, Lipid Bilayer
Routes of Drug Administration
Oral:
Parenteral:
Topical:
Oral (PO): swallow medication
Sublingual: put drug under tongue
Buccal: put drug against cheek
Parenteral: not by mouth
Intravenous (IV): into blood
Intramuscular (IM): into muscle
Subcutaneous (SUBCUT): under skin
Topical: onto skin or mucous membranes
Inhalation: into lungs
Intranasal: into sinus cavity
Transdermal: onto skin
Insertion: into body cavity
Instillation: liquid/cream into body cavity
other miscellaneous routes: p128 – 130 in Gray Morris and Brown
PO route:
IV route:
IM/SUBCUT route:
Topical:
Inhalation:
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PHARMACOKINETICS
•The mathematical description of the concentration of drug in the body
•Absorption
•Distribution
•Biotransformation
•Excretion
Drugs Move Around the Body
Chemical Nature of Drugs
•Most drugs are weak acids / weak bases
weak acid : HA ↔ H+ + A-
weak base : HB+ ↔ H+ + B
•Can exist in ionized / non-ionized forms
•Only non-ionized forms of drug can cross membranes
Drug Movement Across Membranes
•Membrane = phospholipid bilayer
Passive Diffusion
•Moves through lipid bilayer
•Energy-independent
•Follows concentration gradient
•Non-selective
•Non-saturable
•Small, neutral drug
Facilitated Diffusion
•Energy-independent
•Follows concentration gradient
•Tied to movement of another molecule
•Selective
•Small drugs use this route
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Document Summary
Instillation: liquid/cream into body cavity other miscellaneous routes: p128 130 in gray morris and brown. Pharmacokinetics: the mathematical description of the concentration of drug in the body, absorption, distribution, biotransformation, excretion. Chemical nature of drugs: most drugs are weak acids / weak bases weak acid : ha . H+ weak base : hb+ : can exist in ionized / non-ionized forms, only non-ionized forms of drug can cross membranes. Drug movement across membranes: membrane = phospholipid bilayer. Passive diffusion: moves through lipid bilayer, energy-independent, follows concentration gradient, non-selective, non-saturable, small, neutral drug. Facilitated diffusion: energy-independent, follows concentration gradient, tied to movement of another molecule, selective, small drugs use this route. Active transport: moves through protein, energy-dependent, works against concentration gradient, selective, saturable, site for drug interaction. The movement of drug from its site of administration into the blood . Factors controlling absorption: lipid solubility of drug, route of administration, state of drug.
