Drug Interactions

Drug interactions are the reason why we need to read labels for prescribed or over-the-counter drugs. They can cause unexpected side effects, make drugs less effective or increase the action of a certain drug.
Types of drug interactions:
Drug-drug interactions: these interactions occur when two or more different drugs are administered together. Side-effects are inevitably brought about by this type of interaction but these effects are intensified if the drugs that are taken have the same effect: aspirin and warfarin, for example, both help to reduce blood clots unless they are used in conjunction with each other to cause excessive bleeding.
Drug-food/beverage interactions: certain ingredients in food or beverages (e.g. alcohol) can affect the way in which drugs function. Grapefruit juice is a classic culprit: this type of juice has the effect of inhibiting enzymes which break down statins (drugs used to lower cholesterol levels) in the intestines. The result is that more of the statins are absorbed into the bloodstream, increasing the risk of toxicity.

[Side Note]
The opposite of enzyme inhibition is the enzyme-inducing effect. In this case, drug metabolism is increased meaning that enzymes work more effectively to break down the drug so that it is excreted from the body more rapidly. Therefore, the drug does not stay in the body long enough for the full effects of the drug to be realised, making the drug less effective. This can have disastrous consequences: if a morning-after pill is taken, for example, along with an epileptic drug such as carbamazepine, the pill will not function properly, leading to an unwanted pregnancy.

Drug-condition interactions: such interactions occur when drugs exacerbate the symptoms related to major health conditions. This is why asthmatics, for example, are advised not to take ibuprofen due to the risk of an allergic reaction, which can result in airway constriction.

And the take-home message?
The next time you walk out of a pharmacy, make sure that you know what can go wrong with the use of your medication. If you plan to avoid the gruelling process of reading the information leaflets, make sure you have a conversation with somebody well-versed in drug interactions to avoid falling victim to medical malpractice.

By Kumaran Rajaratnam.

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