Intro To Pharm Flashcards
IM
Intramuscular
Rapid admin
Quick onset
IV
Intravenous
Most rapid form
100% bioavailability
Immediate onset but also toxic
Oral
Most convenient GI transit time- prolong time decreases absorption Gastric pH- acidic enviro malabsorption Bioavailability- Co-admin
SL
Sublingual or Buccal Under cheek or tongue Ease of admin Rapid absorption Subsequent bioavailability
SQ
Subcutaneous Injection into fat Great for long acting injection Variable absorption Stomach and arm faster absorption
IT
Spinal cord
Rare elderly Pt with poor venous access
Rectal
High perfusion area
For ancillary treatment
If they have nausea or vomiting
Inh
Lung tissues large SA for absorption
Rapid onset
Popular for abuse
Transdermal
Skin admin Look for multiple patches Patches cut open Predetermined time period Fetanyl-chronic pain
Oral liquids
Peds and elderly
Bypass barrier for absorption
Great Bioavailability!
Fastest to Slowest
Onset
IV-IM-SL-oral liquid-oral solid-depot injection(SQ)
What is the #1 reason people stop taking their meds?
Side effect
BA (F)
Bioavailability
True total amount of drug that reaches gen circulation
F=1 is 100%
Bioequivalence
Brand vs generic
Same drug in similar doses reaches gen circulation at same relative rate and extent (super impossible)
Clinical or Therapeutic Equivalence
Same drug 2 or more doses gives identical effect or 2 drugs from same class compared
Bioequivalent has to be clinical equivalent not other way around
Clinical outcome is similar
What’s most important when looking at drug studies?
Pharmacodynamic effect of drug on body and safety endpoint
Pharmacodynamic
What drug does to body
Pharmacokinetic
What body does to drug
Potency
Amount of med must be admin to achieve dynamic response
Therapeutic or toxic response
Compare activity of drug in same class
Reciprocal of dose
Only significant if fewer side effects or admin less often
Absorption
Time for dose to enter circulation
Determines bioavailability
Pt variability
Most psychotropics absorbed in GI Tracy
Distribution
Time for dose to reach desired site of action
BBB
Can delay pharmacodynamic effect
Factors-
Molecule size
Lipophilicity
CSf fluid ph
Protein binding
Side effect because distribute to other organ
More fat - more prolonged drug distribution
Only unbound drug is active
Metabolism
Bio transformation
Body’s way of getting drugs ready for elimination
Occurs in liver 99% of time
If you inhibit you block metabolism and body can’t eliminate so bp keeps dropping
Cyt P450 enzyme system in liver
Isoenzymes indidually responsible for metabolism of enzymes
HUGE source of drug and adverse rxn
Metabolite
Transformed molecule
Often more active then parent
Ability to metabolize impaired in chronic ill
Increased in kid under 12 and pregnant
Most psych meds metabolize in liver excrete via urine
Enterohepatic recycling
Liver excretion reabsorb in intestine
Renal
Kidney
Most excreted
Declines with age and disease
Half life
Time for dose to undergo pharmacokinetic response
Lower blood by 50%
Takes 6-7 half life’s to completely eliminate drug
Steady state (SS)
5-6 half life’s required to have passed with routine admin
When the amount of drug absorbed or administered is =to the amount eliminated over each dosing interval
Only time PT can be objectively assessed
Test for clinical effectiveness
Independent of dose admin or dosing interval
Toxicity checked earlier
Drug level monitoring
When there is no clear therapeutic or toxic endpoint
Lithium changes quickly
Safe serum is narrow
Psych meds that require monitoring
Trycyclic antidepress Elavil Tofranil Pamelor Mood stabilizers Carbamazepine Lithium Valproic acid
Protein bound shuts it down Patients age Renal hepatic fxn More useful in assessment of adverse drug rxn Clinical eval more useful
Drug level monitoring
Drug interactions
Occurs with co admin of two or more drugs
Similar therapeutic or synergistic effect: additive or synergistic
Diminished or enhanced absorption
Grapefruit inhibit Cyt P450
Inducer- drug levels decrease faster
Enzyme inhibitor- stop metabolism of drug
ED and LD
Lethal dose and effective dose
Look at LD1:ED99
ADR
Adverse drug rxn Undesirable effect of med Go to site of action when you don't want to Onset is variable Drug interaction Switch class Discontinue Reduce dose Manage with other drug
Common ADR with psych meds
Drowsiness/Insomnia Antidepress, neuroleptic, hypnotic, mood stabilizer N/V All meds Sex dysfunction SSRI antidepressant Weight gain/loss Antidepressant, neuroleptic, mood stabilizer Cognitive impairment Psychotropic Dry mouth TCA/anticholinergic Movement disorder 1st gen neuroleptic,
Geriatrics
Thyroid disorders Polypharmacy Delayed gastric emptying Decreased aplchnic blood flow Elevated gastric ph Impaired intestinal motility Extent not affected - do not fully absorb Decreased body water Increased half life because fat Decrease protein binding increase toxicity 50% renal excretion age 70 BUN helpful 5-25 blood Uria nitrogen Renal number up renal fxn down
