| Why are some medicines taken before food and some after food? |
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Question:
Why are some medicines taken before food and some after
food?
Answer:
Medicines must be absorbed into our
body for them to have an
effect. The absorption of medicines into our body is affected by the chemical
properties of the medicines, and the presence of food or certain kinds of food
in the stomach.
When food comes
into contact with our stomach lining, it stimulates the stomach to secrete
digestive juices. The
pH (a measure of acidity, ranging from 1 to 14) of the stomach is lowered by the
digestive juices. This acidic condition (low pH) is
unfavourable for absorption of certain medicines, affecting the efficacy
of the medicines. Therefore such medicines work
better if taken half an hour to an hour before
food.
On the other hand,
medicines that are likely to cause stomach discomfort should always be taken
with or after meals. These medicines which irritate the stomach lining
include
aspirin and non-steroidal anti-inflammatory medicines (NSAIDs) eg:.mefenamic acid and naproxen.
Taking medicines with or after meals can minimize this
effect.
Most medicines are
broken down by enzymes
via a process known as metabolism in the liver. The enzymes
may be affected by certain food, e.g grapefruit is known to inhibit the
function of some enzymes. This can influence the
efficacy and side effects of the medicines. Hence medicines should not be taken
at the same time with such food.
Source:
Cheong Han Hui, Pharmacist, Pharmaceutical Society of Singapore
More information and advice can be obtained from your pharmacist. Send your questions to sthealth@sph.com.sg.
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