Why do some medicines cause coma when taken as pieces, but some are fine when taken as chewed?

Some time ago, a news story about a woman who fell into a coma after taking her blood pressure medication in pieces attracted widespread public attention. While people were generally curious about why taking medication in pieces would lead to a coma, they were also rethinking whether the way they usually take medication is correct.

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Today we will take a look at which medicines cannot be taken separately and how to determine how to take the medicines.

01Why does taking antihypertensive drugs separately cause coma?

Nifedipine has many different dosage forms. Among them, the common tablets, nifedipine tablets (10 mg per tablet), are used 1 tablet at a time, 3 times a day for the treatment of hypertension. It takes effect quickly, but is also absorbed and disappears quickly. Usually, one tablet completes its mission in 4 to 6 hours. Patients need to take the next tablet on time to maintain a stable drug concentration in the body, but frequent use of the drug will bring some inconvenience to people.

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Therefore, many patients will choose nifedipine controlled-release tablets (30 mg per tablet), which has a dosage three times that of ordinary tablets and only needs to be taken once a day, which is much more convenient. In the news, the antihypertensive drug taken by the person concerned was nifedipine controlled-release tablets. The outer layer of nifedipine controlled-release tablets is wrapped with a specially designed shell , which has the characteristic of "water can come in but the drug cannot go out", which is like installing a "timed release" device on the tablet, ensuring that the drug can be released in the body at a uniform and stable rate, thereby achieving a 24-hour stable blood pressure reduction effect. When the drug is released, complete empty tablets can even be found in the feces.

Image source: CCTV 13

However, once the nifedipine controlled-release tablets are bitten or broken, their delicate controlled-release structure will be destroyed , just like a punctured balloon, the drug will "pour out" in a short period of time. Such a large dose of drug released at a very fast speed will inevitably lead to an abnormal drop in blood pressure, and then cause severe hypotension symptoms , such as coma.

02Which medicines cannot be opened at will?

In addition to controlled-release tablets, the following types of drugs should not be broken apart and taken. If they are broken apart and taken, it may cause the drug to become ineffective, increase side effects, or even cause poisoning.

1) Sustained-release drugs

Similar to the principle of controlled-release drugs, the original intention of the design of sustained-release drugs is to slow down the process of drug release . Breaking it apart and taking it will accelerate the drug release rate and may cause adverse reactions. Of course, some sustained-release tablets are designed with "split tablets" that can be completely cut along the dividing line and used as appropriate, but they cannot be chewed or ground before taking.

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2) Enteric-coated preparations

This "intestinal exclusive" enteric-coated preparation is designed to ensure that the drug can be released and exert its effect in the small intestine , to prevent the drug from "getting lost" in the stomach and being decomposed prematurely, and to prevent irritation to the gastric mucosa. If the enteric-coated preparation is broken open, it may not only irritate the gastric mucosa, but also cause the active ingredients to be destroyed by gastric acid, affecting the efficacy of the drug and even causing harm.

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3) Coated tablets

Coated tablets include sugar-coated tablets, film-coated tablets, etc. The coating can prevent moisture, avoid light, and cover up bad odors , etc. If you break it apart, these protective effects will disappear at the same time.

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4) Chemotherapy drugs and targeted drugs

This type of drug is inherently highly toxic, and taking it apart may increase the risk of toxicity to the mucous membranes of the oral cavity and other places, and produce cytotoxic effects on the human body.

03 "Fancy" way to take pills

In addition to pills that are swallowed whole, different medicines have different ways of being taken depending on their ingredients, mechanisms of action and other characteristics. Some can be broken apart, chewed or taken with water.

1) Dispersible tablets

Dispersible tablets can be taken directly with warm water, or the tablets can be dissolved in warm boiled water and taken. They are especially suitable for the elderly, children and other groups when the tablets are large and difficult to swallow. This drug design effectively solves the problem of "difficulty in swallowing".

2) Chewable tablets

Chewable tablets need to be fully chewed in the mouth and then swallowed with a small amount of water. They are suitable for situations where the drug needs to be absorbed quickly. Friends who are greedy and often have stomach pain after eating too much should be very familiar with this.

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3) Sublingual tablets

Sublingual tablets are tablets that are held under the tongue in the mouth. The drug is absorbed through the oral mucosa and directly enters the systemic circulation and is distributed throughout the body. It is important to remember that this type of tablet can only be held under the tongue and cannot be swallowed .

4) Effervescent tablets

The most familiar effervescent tablets are probably vitamin C effervescent tablets. You only need to put the tablets in an appropriate amount of water, shake them well after the bubbles are released, and you can take them. They are very suitable for children and situations that require quick dissolution. However, it should be noted that effervescent tablets cannot be swallowed or held in the mouth , because taking them directly will produce a large amount of gas in the mouth or digestive tract, which may cause suffocation and gastric perforation.

To know how to take different drugs, you still need to read the instructions carefully and fully understand the usage and precautions of the drugs. Because different drug dosage forms have different methods of administration, incorrect use may turn "treatment" into "disease-causing". At the same time, please be sure to take the drugs strictly according to the doctor's instructions. If you have any questions about the method of taking the drugs, remember to consult a pharmacist in time. They are your "think tank" for safe medication. Author: Wang Qian, Ph.D. in Pharmacology, Shanghai Drug and Medical Device Adverse Reaction Monitoring Center

Planning & Editing: Ding Dong

Acknowledgements: Dr. Jun Hu from Shanghai Center for Adverse Drug and Medical Device Reaction Monitoring provided scientific guidance for this article