What is the definition of pharmacokinetics?
Study of drug movement throughout the body
What are the 4 steps to pharmacookies?
Movement of drug from its site of administration into the blood.
Movement of a drug from the blood to the interstitial space of tissues and from there to the cells.
Enzymatically mediated alteration of drug structure.
Movement of drugs and their metabolites out of the body.
What are three ways to cross the cell membrane?
1. Channels are pores (smallest)
2. Passage with the aid of a trasnport system
(this is very selective and may use energy)
3. Direct penetration of the membrane itself. Must be lipophilic (lipid soluble). Most common.
In what direction do lipid soluble drugs move?
Drugs move from areas of highest concetration to areas of lower concentration.
What are two types of non-lipid soluble drugs that move across membranes?
1. Polar molecules
Neither of which move easily.
Should drugs be ionized or non-ionized to be absorbed?
How does pH affect ionization?
Acids IONIZE in alkaline media.
Bases IONIZE in acidic media.
What is ion trapping?
Drugs accumulate on side of membrane where pH favors ionization. Dangerous with pregnancy.
What are FIVE factors that affect drug absorption?
1. Rate of dissolution
2. Suface area
3. Blood flow
4. Lipid solubility
5. pH partitioning
What are EIGHT routes of administration?
How are drugs distributed?
-blood flow to tissues
-exiting the vascular system
How does blood flow to tissue work?
Drugs are carried to tissues and organs via the blood.
How does exiting the vascular system work?
Drugs must exit vascular system to produce desired effects.
Where does metabolism usually occur?
What is significant aboutcytochrome P450?
Causes genetic alterations in drug metabolism correlates to these enzymes.
How does P450 act as an inhibitor?
Decreased emtabolism of substrates which leads to increased drug effect unless drug is a prodrug.
How does P450 act as an inductor?
Increased drug metabolism of substrates which leads to DECREASED drug effect unless drug is a pro drug
What is a prodrug?
Does not become active until it hits the liver.
What do NAT's do?
catalyze the transfer of an acetyl group to particular drugs, inccreasing their water solubility
What does TPMT do?
Involved in metabolism of thiopurine agents. Inactive the cytotoxic effects of these drugs.
How is genetic testing significant in regards to metabolism?
Study of allelic differences associated wtih individual variability in drug response. Detects presence/absence os these enzymes and their metabolism characteristics.
What are SIX therapeutic consequences of drug metabolism?
1. Renal drug excretion
2. Inactivation of drugs
3. Increased therapeutic action
4. Activation of pro-drugs
5. Increased toxicity
6. Decreased toxicity
What are FIVE special considerations in regards to drug metabolism?
2. Induction of drug metabolyzing enzymes
3. 1st Pass Effect
4. Nutritional Status
5. Competition between drugs
How are the majority of drugs excreted?
What are the 3 steps of Renal Drug Excretion?
1. Glomerular filtration
2. Passive tubular reabsorption
3. Active tubular secretion
What are THREE factors that modify excretion?
1. pH dependent ionization
2. Competition for active tubular transport
What are the three phases of Time Course of Drug Response?
1. Time drug response starts.
2. When drug response is most intense.
3. Time when drug response ceases.
What is the correlation between plasma drug levels and drugs?
Usually direct correlation between therapeutic and toxic responses and plasma drug levels.
What are FIVE other types of non renal excretion?
1. breast milk
What are the two types of drug levels?
1. Minimum effective concentration (MEC)
2. Toxic concentratino
What type of range do we want for drug levels?
What is the definition of a drug 1/2 life?
Time required for amount of drug in body to decrease by 50%
What are FOUR techniques to reduce fluctuations in drugs in the system?
1. Plateau drug levels
2. Continuous infusion
3. Reduce the dosage size and interval
4. Loading dose vs. maintenance dose
How does one maintian plateau drug levels?
If administered repeatedly in same dose, plateau reached in 4 half lives. Will be 94% out of system in four half lives.
What phase does IV pass?
What is PUSH when it comes to drug administration?
Dissolve in the least amt of liquid possible and insert as close to the site as possible.
What are two reasons for IM use?
1. depot (oil based) drugs
2. poorly soluble drugs
When is Dana's birthday?
Sunday, June 3rd!!!!