Drug Drug Interactions Flashcards
What is defined as drug drug interaction?
Modification of a drug effect by prior administration of another drug, herb, foodstuff, drink
When has a drug interaction occurred
When the interaction between a number of drugs produces an effect which is different from the effect of their own direct functions
Define “object drug”
A drug whose activity is effected by drug interaction
Define Precipitant
The agent that precipitates drug interaction
Causes
Are drug drug interactions aways detrimental?
NO
What is common amongst all the drugs associated with serious interactions?
They all have a relatively low therapeutic index -can easily lead to profound toxicity
Who are the susceptible patients to drug drug interactions?
The elderly
The young
The critically ill
Patients undergoing complicated surgical procedures
Patients with chronic conditions (liver disease, renal impairment, diabetes mellitus, epilepsy, asthma)
What are the possible effects on the pharmacodynamic effect on a drug due to drug drug interactions?
Antagonistic interactions
Additive or synergistic interactions
Interactions due to fluid and electrolyte disturbances.
What are the possible effects on the pharmacokinetic effect on a drug due to drug drug interactions?
Alteration of ADME
How can the absorption of a drug be altered?
Formation of insoluble complexes
Altered PH
Altered bacterial flora
Altered GI motility
When is delayed absorption a hindrance?
When the drug has a short half-life or when we want high plasma levels quickly.
How do changes in pH affect absorption?
The degree of ionisation is dependant on pH.
Absorption is determined by the degree of ionisation.
Where are most oral medicines absorbed?
In the small intestine
What is the rate limiting step of oral drug absorption?
Gastric emptying
When does protein binding displacement occur and what pharmacokinetic factor does it affect?
Occurs in reduction in plasma protein binding of drug caused by presence of another drug.
Affects Distribution
