Pharm 2 Flashcards
What is meant by the term pharmacokinetics?
What the BODY does with the drug (absorption, distribution, metabolism and elimination)
What is meant by the term pharmodynamics?
What the drug does to the body
What is meant by the term “therapeutic window”?
Therapeutic window = the range in which the drug will act (above is toxic), below means no effect.
What are the two most common routes of drug administration?
- Oral meaning into the mouth
- Parenteral - technically meaning beside the intestine (however this could also encompass drugs that have been given by injection)
Differentiate between the terms “bolus dosing” and “constant rate of infusion”:
- Bolus dosing = dosing all at once
- IV = a constant rate of infusions (CRI)
What is meant by the term bioavailability of a drug and what is it benchmarked against?
Refers to the rate and the extent of drug absorption into the blood = bioavailability (measured against IV)
What is pharmaceutics?
How different preparations of drugs influence absorption rates
What is the rate limiting step in drug absorption?
Solubilisation of drug into aqueous environment of gut = the rate limiting step
What are the four factors that will influence the level of drug absorption?
- Drug solubility
- Surface area
- 1st pass metabolism
- Vascularity/Disease processes
Briefly describe how first pass metabolism works:
With the exception of the oral mucosa and the rectum. All absorption from the alimentry canal goes directly into the portal vein. The drugs are then exposed to metabolising enzymes in the liver before reaching the final systemic blood supply.
What options are available to decrease the impact of first pass metabolism?
- Give a higher dose
- Give the drug trans-mucosal
- Inhibit hepatic metabolism with another drug
Explain the difference between the pattern of drug distribution and the volume of distribution:
Volume of distribution (Vd) = propensity for a drug leaving the blood and entering tissues
Vd does not inform on the pattern on distribution
What is the official definition for the volume of distribution?
The volume into which a drug appears to be distributed with a concentration that is equal to that of plasma. A proportionality constant.
What is the effect of protein binding on a drug?
Protein binding means the blood is not easily able to escape the circulatory system.
