Drug Interactions Flashcards
What are the different types of interactions?
Drug-Drug Drug-food/drink Drug-herbal Drug-chemical Drug-labatory test
What is a drug interaction?
An interaction is said to occur when the effects of one drug is altered by the co-administration of another drug, herbal medicine, food, drink or environmental chemical agent.
What are the outcomes of drug interactions?
Additive or enhanced effect of one of more drugs
Antagonism of the effect of one or more drugs
Toxicity
Loss of therapeutic effect
What is clinically significant in drug interactions?
A combination of therapeutic agents which have direct consequences on the patients condition
It can be beneficial or detrimental
What are the rates of adverse drug reactions (ADR)
6-10 drugs -7%
16-20 drugs- 40%
Patient groups at risk of ADR
HIV Epilepsy Hepatic or renal disease Diabetes Intensive care Transplant recipients Undergoing complicated surgery More then one prescriber Long term therapy for chronic diseases
Examples of drugs with high concentration dependant toxicity
Digoxin
Warfarin
Lithium
Cytotoxic agents
Examples of drugs with a steep dose response curve
Verapamil
Levodopa
Sulphonylurease
Examples of drugs with patient dependant on therapeutic effect
Immunosuppressant glucocorticoid Oral contraceptives Anti-epileptics Anti-psychotics Anti-retrovirals
Examples of drugs with Salvable hepatic metabolism
Alcohol
Phenytoin
What are pharmacodynamic interactions
Antagonist reactions
Additive or synergistic interactions
Serotonin syndrome
Drug or neurotransmitter uptake interactions
What is an antagonist pharmacodynamic interaction?
Agonist and antagonist of specific receptor sites have opposing pharmacological actions
What is an additive or synergistic interaction?
Two drugs with similar pharmacological effects given together can give additive or synergistic effects.
E.g alcohol and benzodiazepines = increased sedation.
What is serotonin syndrome?
An excess of serotonin that results from therapeutic drug use, overdose or inadvertent interactions between drugs.
Symptoms include fever, diarrhoea, sweating, confusion, hypertension and abnormal movements
What is a drug or neurotransmitter uptake?
MAOIs reduce the breakdown of non adrenaline in the adrenergic never ending.
