Pharmacology: Drugs and the Blood Flashcards
(33 cards)
What drug characteristics increase the consequences of plasma protein displacement?
Drugs that are highly protein bound, have high clearance rates, and where dosing is not titrated to effect suffer more severe consequences from plasma protein displacement.
Why is displacement of highly plasma protein bound drugs extremely important?
Because very small changes in plasma binding in highly bound drugs translate into large changes in active unbound drug concentrations
Is plasma protein binding consistent for the same drug?
No, there may be some variability in plasma binding of the same drug between patients.
Do newborns or adults usually have more or less drug bound to protein?
Usually adults have a higher proportion of protein bound drug than newborns.
What is G6PD deficiency?
G6PD deficiency has been associated with drug induced hemolysis.
Adverse reactions to drugs are dependent on what drug factor?
Dose
Why are some drugs contraindicated in G6-PD deficiency?
Pegloticase, Quinine, Rasburicase, Sulfamethoxazole.
How do some drugs cause Eryptosis?
Some drugs increase the RBC permeability to Ca which stimulates the loss of K and cell membrane scrambling that can lead to eryptosis.
Why is the scramblase enzyme important?
Scramblase maintains the proper makeup of the cell membrane.
What general factors lead to thrombocytopenia?
Bone marrow does not produce enough.
The body destroys platelets.
The spleen holds too many platelets.
Or any combination of these factors.
What is heparin induced thrombocytopenia?
PF4 binds to heparin causing it to become an antigen for antibodies. Takeup by platelets causes platelet activation, aggregation, and decreased numbers of platelets available for normal clot formation.
What are fractionated heparins?
Fractionated heparins are fragments of heparin that are smaller but have similar effect.
Why is the drug (heparin) needed for HIT?
Because with all drug induced antibody bindings the complex of drug and antigen is required for antibody binding
What is the most common cause of peripheral blood cytopenias in the industrial world?
Myelosuppression is easily the most common cause of cytopenias in the developed world.
How can drugs cause myelosuppression (generally speaking)?
myelosuppression can occur by decreased bone marrow production or shortened peripheral blood survival.
What is idiosyncratic myelosuppression?
Idiosyncratic myelosuppression is achieved by shortening peripheral blood survival.
What are some non-cytotoxic mechanisms of myelosuppression?
Induction of defects in hematopoietic cells, damage to stromal microenvironment,
Inhibition or destruction of growth factors.
humoral or cellular immunosuppression.
How is drug induced myelosuppression managed?
Rapid empiric antimicrobial therapy must be used if infection is suspected. Also EPO, G-CSF, and GM-CSF can be used to try and stimulate blood cell development.
What is drug induced agranulocytosis?
Many drugs are associated with rare instances of agranulocytosis which is a deficiency of granulocyte production.
What is unique about the timeline of drug induced agranulocytosis?
It is highly variable between drugs and some drugs do not exhibit agranulocytosis until they have been given for a substantial period of time.
What are antiplatelet drugs?
(1) Thromboxane inhibitors
(2) PAR1 antagonists
(3) ADP receptor antagonists
(4) Alpha 2 B3 inhibitors (prevent aggregation)
What are fibrinolytic drugs?
Drugs that cause clots to break up.
What are anticoagulation drugs?
Drugs that prevent the formation and propagation of clots. (warfarin, heparins, dabigatran)
What is the major concern associated with non-vitamin K targeted anticoagulants targeted at thrombin ?
There is no way currently to stop severe bleeding should it occur in patients taking drugs like dabigatran.
