Drug Interaction


Introduction- The change in the action or side effects of drug caused by collateral administration with beverage , supplement , food or another drug is drug interaction.
A drug interaction occurs when a substance affects the activity of a drug , either by increasing or decreasing its efficacy or we can say alternatively a new effect is observed that is not observed with just a drug alone . Due to drug interaction pharmacological effect of one or both drugs may be increased or decreased or a new and unanticipated adverse effect may be produced.
Drug interactions may result from pharmacokinetic interactions (absorption, metabolism and excretion ) or from interactions at drug receptors.

Example of Drug Interaction :-
One such drug interaction occurs when the antibiotic tetracycline is taken along with substances such as milk or antacids which contains ca, mg and al ions. These metal ions bind with tetracycline and produce an insoluble product that is very poorly absorbed from gastrointestinal tract.

Types of Drug Interactions :-There are several different types of drug interactions we should be aware of-
1) Drug-Drug :- The interaction between two or more prescribed drugs is drug-drug reaction.
Ex- interaction between “warfarin” , an anticoagulant (blood thinner) and “fluconazole” an antifungal medication . Taking these two drugs together can lead to dangerous increase in bleeding.

2) Drug – Non Prescription Treatment :- This is a reaction between drug and non prescription treatment. This include taking prescribed drug with over the counter medication such as herbs, vitamin or supplements.
Ex – this type of interaction occurs between a diuretic – a drug that attempts to rid the body of excess water and salt and ibuprofen.
The ibuprofen may reduce the diuretic effectiveness as it causes body to retain salt and fluid.

3) Drug Food :- When any food or beverage intake alters drug effect.
Ex – some statins (used to treat high cholesterol) can interact with grapefruit juice. If a person take statins and drinks a lot of grapefruit juice too, much of drug may stay in liver increasing risk for liver damage or kidney failure.

4) Drug Alcohol :- Certain medication shouldn’t be taken with alcohol. Often combining some drugs with alcohol may cause tiredness and delayed reactions and it may also increase risk for negative side effects .

5) Drug-Disease :- When the use of drug alters or worsens a condition or disease.
Ex – some decongestants that is taken for cold may increase blood pressure. this is a dangerous interactions for people having high blood pressure (hypertension).

Other Factors that Influence Drug Interaction:-
1) Genetics :– Due to genetic variation in individual some drug work differently in different bodies . that’s why some people process certain medications more quickly or slowly than others . this may cause drug levels to go down or up than as expected.

2) Weight :– Drug doses vary according to a person’s weight. weight changes could affect dosage and also increase or decrease the risk of drug interactions.

3) Age :– According to age body changes in many ways , some of this may affect our response to medications. the kidneys, liver and circulatory system may slow down with age . this can slow down the metabolism and removal of drug.

4) Sex (male/female) :– Differences in anatomy and hormones may affect drug interaction as well.

5) Lifestyle :– Some diets that people follow can be a problem when combined with medication.
Ex- high fat uptake can reduce the response of bronchiodilaters.

To Avoid Drug Interaction :-
People can avoid possible drug interaction by talking to a pharmacist. People should ask the pharmacist how to take drug and what to expect.
Pharmacists have extensive knowledge of how drug works, their side effects, medication, supplements and foods they interact with. In fact, you may want to bring your prescription and non prescription drugs as well as any supplements to the pharmacy while picking up a new prescription. If the pharmacist identifies any possible interaction among any medication, he or she may be able to suggest a schedule for taking them that will minimize the likelihood of interactions.

Ms. Shipra Singh, B Pharm, IV Semester, School of Pharmacy, Career Point University, Kota

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