10-08-2012, 11:07 AM
DISEASE AND DRUG INTRACTIONS
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Definitions;-
Disease -
a disordered or incorrectly functioning organ, part, structure, or system of the body resulting from the effect of genetic or developmental errors, infection, poisons, nutritional deficiency or imbalance, toxicity, or unfavorable environmental factors.
Drug interactions-
these are undesirable effects/pharmacological actions (in general) It is the modification of the effect of one drug
(the object drug ) by the prior concomitant administration of another (precipitant drug).
Factors contributing drug interactions
Multiple drug therapy
Multiple prescribes
Multiple pharmacological action of drugs
Multiple disease/ predisposing illness
Poor patient compliances
Advancing age of patients
First-pass metabolism:
Oral administration increases the chance for liver
and GIT metabolism of drugs leading to the loss of a
part of the drug dose decreasing its action. This is
more clear when such drug is an enzyme inducer
or inhibitor.
Active tubular secretion;
It occurs in the proximal tubules (a portion of renal tubules).
The drug combines with a specific protein to pass through
the proximal tubules.
When a drug has a competitive reactivity to the protein that is
responsible for active transport of another drug .This will reduce
such a drug excretion increasing its con. and hence its toxicity.
Onset of drug interaction
It may be seconds up to weeks for example in
case of enzyme induction, it needs weeks for protein synthesis
, while enzyme inhibition occurs rapidly.
Prevention of drug interaction
Monitoring therapy and making adjustments
Monitoring blood level of some drugs with narrow
therapeutic index e.g., digoxin, anticancer agents…etc
Monitoring some parameters that may help to
characterize the the early events of interaction
or toxicity e.g., with warffarin administration, it
is recommended to monitor the prothrombin time
to detect any change in the drug activity.
Increase the interest of case report studies to
report different possibilities of drug interaction