Prescription drugs' fine print is important – a toxicologist explains how to decode package inserts to take medications safely and increase their effectiveness
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Monday, April 24, 2023
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With approximately 1.3 million emergency department visits in the U.S. caused by adverse drug events each year, patient education is becoming increasingly important.
Key Points:
- With approximately 1.3 million emergency department visits in the U.S. caused by adverse drug events each year, patient education is becoming increasingly important.
- All prescription drugs come with instructions on how to safely and effectively use them.
- Depending on the medication, there may be several types of information included: the patient package insert, medication guide and instructions for use.
What can I learn from package inserts?
- An often overlooked part of the package insert is the prescribing information.
- Though written primarily for health care professionals, it contains a wealth of information regarding the ways in which the medication interacts with the body.
- If you’d like to follow along, a copy of the prescription information for Lipitor can be found here.
How does the drug work?
- Pharmacodynamics refers to “what the drug does to the body,” which includes the mechanism of action as well as how other factors like drug concentration influences its effects.
- First, the liver is the primary site that produces cholesterol in the body and the area the drug is meant to target.
- And third, the drug increases the number of LDL cholesterol receptors on cell surfaces, ultimately increasing the catabolism, or metabolic breakdown, of LDL cholesterol.
Where does the drug go in my body?
- The pharmacokinetics of a drug are determined by factors related to the chemical itself and the person taking the medication.
- For Lipitor, the prescription insert does not specifically say where the drug goes in the body, but it does note that the volume of distribution is 381 liters.
- On the other hand, chloroquine, an antimalarial drug that enters body fat, has a value of 15,000 liters.
Does the drug cause the effects or its byproducts?
- Though the therapeutic effects of most drugs come from the chemical compound it’s made of, many break down into active metabolites in the body that also have some relevant biological effects.
- Some medications are administered in an inactive form called a prodrug that the body converts into metabolites with the desired therapeutic effects.
How long will the drug be in my system?
- Information about a drug’s half-life is found in the “Excretion” subsection under “Pharmacokinetics.” The half-life for Lipitor is approximately 14 hours.
- This means that the drug’s effects may last even after the drug itself is out of your system.
Why do I need to take medications with food or at certain times?
- For Lipitor specifically, the answer to this question can be found in the “Absorption” subsection under “Pharmacokinetics.” Food decreases the rate and extent of Lipitor’s absorption but doesn’t significantly affect LDL cholesterol reduction.
- The upshot of all of this is written on the drug label on the outside of the package: Lipitor can be taken with or without food.
Why does my doctor ask about other drugs I’m taking?
- For instance, two drugs may rely on the same enzyme system in the body to break them down.
- Taking them at the same time can ultimately lead to higher-than-anticipated levels of either or both drugs in the body.