Safe Prescribing Flashcards
What types of subjects are included in Phase I clinical trials?
Health volunteers that do not have the target disease. About 20 to 80 participants. They are typically not taking any other meds.
How long does a patent last?
Usual patent lasts 9-11 years.
The patent can be extended (usually 3-5 years) if:
*The drug becomes available OTC (i.e. omeprazole).
*They implement a new delivery system (i.e. extended release formulation).
*New dosing regimen.
*New indications (i.e. new use, Canaglifilozon has 8 new indications, patent was extended until 2031)
Pharmacodynamics (PD)
The study of the biochemical and physiological effects of the drugs. What the drug does the the body/disease. The mechanism of action.
The pharmacodynamic profile of a medication is unchanged of the lifespan. True or False?
True. It works the same not matter the age.
Pharmacodynamics knows no age.
Pharmacokinetics - Define ADME
What the body does to the drug:
A - Absorption (skin, lungs, GI tract, praenteral)
D - Distribution (throughout the body, especially to the needed site of action
M - Metabolism (bio transformation, changing it from one form to another - liver, GI tract, other)
E- Elimination (kidney is the most common way a drug is eliminated from the body, GI tract, others)
Pharmacokinetics: True of False?
Age and gender significantly impact a medication’s pharmacokinetics.
Age and gender significantly impact a medication’s pharmacokinetics. True
Fick’s Law
The tendency of molecules to move from higher to lower concentration via random molecular motion. Typically occurs across a membrane or other permeable barrier.
Examples of permeable barriers
*blood brain
*mammary
*placenta
*cell membrane
*Vessels
Passive diffusion
Most common method of diffusion. Moving from higher to lower concentration
Examples of Drugs that cannot be given orally. Why?
Would be killed by the pH in the digestive tract, and the molecules (molecular weight) of these drugs is too big to be absorbed by the GI tract.
Unfractionated heparin
Insulin
LWMH - low molecular weight heparin
Why is Vancomycin only given parental? In what instance could PO Vanco be given?
Vanco molecules are too big to be given PO and would not be absorbed to fight an infection like cellulitis, etc?
PO Vanco could be given to treat a gut infection like CDiff and Enterocolitis. It would not need to be absorbed since it would be going directly to the site of infection.
What parameters need to be met for a drug need to be to be given PO (for oral drug absorption) so that it is absorbed by the gut?
*The molecular weight needs to be <1000 d, most 250-600 daltons
*It needs to be a lipid soluble substance (to pass through the gut wall
*Small intestine needs to be functional (this is where most drugs are absorbed). The stomach does a little bit of breakdown, but the duodenum (the first part of the small intestine) and the rest of the small intestine are the most common points of absorption.
Which scenario would a drug that is given PO have less efficacy?
History of gastric bypass surgery. This is because the duodenum and a portion of the small intestine is bypassed and so the drug would not be absorbed properly.
Area Under the Curve (AUC)
Area under the plot of drug plasma concentration against time after a single dose administration. This means:
The taller thinner curve means the drug peaked quicker and left the body sooner. This is indicative of a young healthy person.
The shorter fatter curve means the drug took longer to peak and longer to leave the body. This is indicative of an older adult.
Meaning, if you administer a sedating pain medication to a younger adult, they get higher pain control that lasts a short period of time. If you give that same medication to an older adult, the get less pain control, but the drowsy effect lasts longer.
Tmax
Time to maximum drug level observed. Time on the clock. Time to peak
Cmax
Measurement of Tmax (maximum or peak concentration of a drug observed after its administration). In other words, Cmax is if you were to measure the drug level, when would it be at its highest and what would that level be.
Tmax,Cmax
Is the maximum effect of the drug
The max clinical effect, and
The max adverse effect.
Basal insulin
Peak-less, Glargine or Detemir, keeps things level. It mimics what the pancreas does in a normal human body. 50% of insulin in the human body is basal.
All drugs of the same class have the same…
Pharmacodynamics
All drugs of the same class have the same…
Pharmacodynamics
What is a potential problem when insulin is at Cmax?
It can cause hypoglycemia. This using happens after a rapid acting insulin bonus. Therefore, hypoglycemia will occur when the rapid acting insulin hits Cmax.
Pharmacokinetics vs Pharmacodynamics
Pharmacokinetics (different) is what the body does to the drug. Therefore, the results can vary.
Pharmacodynamics (same, class effect) is what the drug does to the body. All drugs of the same class will work the same way.
Enteric coated
Releases in the small intestine and they take a while to kick in.
Volume distribution Drug blood concentration
The total amount of drug in the body/
Drug blood concentration
The amount of drug distributed uniformly in the body that produces the observed drug concentration
Why does Naproxen sodium work faster than, plain Naproxen or enteric coated sodium?
This is because the sodium molecule facilitates absorption
What organ makes albumin in the body? Why does the Albumin amount drop as we get older? Why does this matter when talking about drugs?
The liver. Our liver shrinks when we get older. Albumin is the most common plasma protein for highly protein-bound drugs to be attached to. (I.e. Coumadin, warfarin).
Example: Young adult between 20-30 will need more Coumidin or Warfarin than and older adult. Since the older adult has less albumin for the medicine to bind to, if you give them the same higher dose as the younger person, they will have the drug free roaming around the body.
Body fat increases in the average person as we age. Why is this important regarding drugs?
Many drugs are lipophilic and will hang out in the body fat, which makes meds hang around longer
What’s are the age related changes than can affect how drugs are processed?
% body weight as water decreases
Lean muscle mass decreases
% of body fat increases
Serum albumin decreases
Relative kidney weight decreases (the kidneys shrink)
Relative hepatic blood flow decreases (less able to do drug bio transformation in a timely manner)
In the older adult why will antibiotics not be well distributed?
Because an older adult has less extracellular water, so the antibiotics don’t distribute as well.
Protein-bound?
Means the 80% or more of the drug (i.e. warfarin, Heparin, carbamazepine, phenytoin) circulates via plasma protein (i.e. albumin)
Why does THC and PCP (angel dust) hang around in the body?
B/c it is highly lipid soluble.
How long does a person initiating oral bisphosphonate therapy need to be on alendronate to treat osteoporosis with history of fragility fracture and why?
3-5 years; this b/c the drug settles in the bone and hangs around a while. Bones hold on to meds for a long time (i.e. children in the 50s and 60s exposed to lead paint chips, lead was found in the bone for decades)
How long does a person initiating oral bisphosphonate therapy need to be on alendronate to treat osteoporosis with history of fragility fracture and why?
3-5 years; this b/c the drug settles in the bone and hangs around a while. Bones hold on to meds for a long time (i.e. children in the 50s and 60s exposed to lead paint chips, lead was found in the bone for decades)
How are a vast majority of drugs offloaded?
Through the kidney; Most oral drugs are fat soluble to get through the gut wall and then must be biotransformed to water soluble form to be offloaded through the kidney
Where are the primary biotransformation sites in the body?
Primary is the liver
Less active sites are:
GI tract
Lung
Skin
Kidney
Between a female and a male of the same height and weight, which accounts of 2/3 drug-induced liver toxicity and why?
The female, b/c the female’s liver is smaller which means she produces less hepatic enzymes. In addition, the female stores more fat, and therefore will store more of the fat soluble drug and needs to be expelled by the the liver.
First pass effect (AKA Pre systemic Elimination)
Biotransformation/excretion of oral drug by hepatic mechanisms, the result in minimal delivery into systemic circulation
Meaning the liver takes a portion of the drug and throws it away before it can reach systemic circulation
Drug dose are adjusted by the manufacturer through the phase clinical trials to accommodate first-pass effect
First pass effect and routes
Oral route is subject to first-pass effect, the IV route is not subject to first-pass effect. Therefore the oral dosage of the drug will be higher.
Bioavailability
Means how much of the drug is available after first-pass effect.
Which statins are best taken during the day? Why?
Which statins are best taken a nighttime? Why?
Simvastatin, pravastatin, lovastatin - because these statins have a shorter half-life and our bodies make LDL mostly at night
Atorvastatin and Rosuvastatin - because these statins have a longer half life they will be effective all day
Drug for community acquired pneumonia? Which for is better, Oral or parenteral?
Levofloxacin (Levaquin). They are equal; Both routes have 99% bioavailability.