Basic Phamacology ( chap 1 ) Flashcards
What is a drug
- substance that alters physical state
- chem+empiracle+generic+trade name
dose description
- mg/kg
- dose response curve ( Effective Dose 50%/Lethal Dosd 50%)
- Therapeutic index(TI) = LD50/ED50
- -> larger TI = safer drug
Potency
- comparing two drugs w/ same effects but different ED50
- lower ED50= higher potency
Effectiveness
dif in max effect between two drugs at any dose
Primary vs . side effects
-effect for which the drug was taken
vs
-additional effect
Drug interactions :
- type
- use
- antagonism(shirt curve right)
additive effect(shift left)
superadditive/potentiation( effect of A shifts B DRC further then predicted)
Pharmacokinetics
way the body metabolizes, excretes and move drugs
Routes of administration (parenteral sites)
- parenteral (skin)
- Vehicle (physiological saline)
- Subcutaneous (rely on absorbance below the skin and rate to reach b.s.)
- Intramuscular (rely on absorbance in muscle and rate to reach blood stream)
- Intraperitoneal (rely on absorbance in body cavity to reach b.s.)
- Intravenous (directly through blood stream)
Absorption from:
- parenteral sites
- Transdermal site
- capillary-> heart-> artery -> capillary-> vein
- single layer of cells w/ pores(nutrients, waste, drugs pass freely)
- more in peritoneum>muscle>skin
- diffusion: movement from [higher] to [lower]
- depot injection: last 4 weeks (antipsycholics : [high] in OIL often intramusclar )
- Epidermis
Inhalation of Gases:
-routes and processes
Lungs:
-drug absorption /higher efficient + diffusion is bilateral + fast (bypass liver metabolism) == delivered with precision
- smoke+solid are dissolved in moist lungs and unidirectional== metabolized
Intranasal:
-nasal+lung+ digestive absorption
Oral absorption
- Peroral
- Suppository
Processing of Drugs
- ) Absorption (rate of dissolution: blood flow+Surface Area +Lipid solubility {higher LS=higher absorbance} @ admin site)
- )Distribution (pH partitioning: drug that ionize in blood and NOT @ admin site= increase absorbance)
- )Metabolism:(biotransformation) enzymatic alterations of drug structure
- )Excretion: removal of drug from body
* ** increase dissolution= increased absorption= increased effect
Crossing the Phospholipid bilayer
- ) membrane channel/pores (small molec)
- ) Transport proteins ( selective carriers)
- ) Direct diffusion (‘like’ dissolves ‘ like’)
pH dependent ionization
- acid+acid solution => LS
acid + alkaline solution => Ionize - base +acidic solution=> Ionize
base+alkaline solution=> LS
Digestive System
- intestine wall lipid bilayer (pH=3.5)
- dependent on LS + oil partition coefficient
- -> pKa rate of movement across membrane
pKa
pH @which 50% ionized and 50% LS where drug can diffuse through membrane
pH partitioning/ Ion trapping
- drug accumulates on ionization side of membrane
- pH dependent ionization predict at which environment/pH the drug will accumulate
Obstacles for drug absorption
- BBB: made of PB +influx pumps(deliver nutrients from capillarity to brain and vice versa {OATP2})+efflux(mutli drug resis. pump–> move drugs OUT){lipisomes overload and modify for OATP2}
- Lipid Bilayer(PB): permiable to small or LS molec
Distribution routes
-Liver: (major metabolic enzyme)
–> Alcohol dehydrogenase(remove H+ and increases with the amount of consumption = enzyme induction)=into metabolites(increase usefulness or decrease toxitiy of material==> increase ionization)
=>detoxification
-Kidney:(filters everything out then reabsorbs)
–> Nephron (long tubes: mil per kidney)+ Bowman’s Capsule(glomerulus which are clumps of capillaries)
–> diffusion from blood to glomerulus then back if needed
–> Passive or Active Transport back into blood, if no the excreted
Disulfiram
absorbed through digestive track and last 2 weeks
-in combination with alcohol and negative reaction (detour alcholism )
First-Pass Metabolism
- rate of excretion/half life
- decrease effectiveness of kidney with decreased [drug]
- negative exponential curve ( % / min )
Factors that alter drug metabolism
= stimulants of enzyme system
=depressants of enzyme system
Therapeutic Window
- below toxic level+ above therapeutic level
- optimal dosage for ideal effecets
