Do you really know how to use nitroglycerin tablets? Improper use will make the "life-saving medicine" ineffective

Nitroglycerin is a "life-saving drug" that patients with coronary heart disease always carry with them. It can relieve the symptoms of acute angina pectoris within a few minutes. However, many people complained to Huazi that the use of nitroglycerin during angina pectoris did not quickly relieve the symptoms. Why is that?

After talking with them, Huazi found that many people had misunderstandings on the use of nitroglycerin. They used improper methods when taking it, which resulted in the "life-saving medicine" losing its effectiveness.

1. Drugs that are taken sublingually and cannot be swallowed and absorbed by the human gastrointestinal tract must first enter the liver through the portal vein and be metabolized by the liver before entering the blood circulation. Some drugs will be metabolized and ineffective in the liver, resulting in a decrease in the total amount of drugs entering the circulation. This process is called the "first-pass effect."

The "first-pass effect" of nitroglycerin is obvious, and its bioavailability after oral administration is only 10%. Therefore, nitroglycerin cannot be swallowed, nor can it be placed on the tongue and taken as an ordinary lozenge. It needs to be placed sublingually and absorbed through the sublingual mucosa to avoid the "first-pass effect". The bioavailability can reach 80% before it can exert its normal efficacy.

Second, it is not advisable to use too much at a time. In movies and TV shows, you can often see someone grabbing a handful of medicine and stuffing it into their mouth for emergency treatment when they have a sudden heart attack. So some people mistakenly believe that the same is true for nitroglycerin, and the larger the dosage, the better the effect. In fact, it is not. Nitroglycerin can cause blood vessels to dilate, and taking a large amount can cause severe hypotension, which can aggravate the symptoms of insufficient blood supply to the heart.

The correct dosage of nitroglycerin is 1 tablet each time, placed under the tongue and taken orally. It usually takes effect within 1 to 2 minutes to relieve angina. If the symptoms are not relieved within 5 minutes, you can take a second tablet. After taking 3 tablets in a row, if the angina is still not relieved, stop taking the medicine and call for help immediately, because this means that myocardial infarction or other diseases may have occurred, not just angina.

3. Carry it with you but not close to your body. Patients with coronary heart disease are at risk of angina at any time, so they need to prepare nitroglycerin tablets with them in case of emergency. But it should be noted that nitroglycerin should be carried with you but not close to your body. Because nitroglycerin is unstable, it is easy to evaporate and decompose after being heated, which will cause the drug to lose its efficacy.

Normally, nitroglycerin needs to be stored in a cool place below 20°C, while the human body temperature is around 37°C. If you carry it close to your body, the body temperature will cause the drug to evaporate and become ineffective. Therefore, when carrying nitroglycerin tablets, you can put them in a bag or in the pocket of your coat instead of keeping them close to your body.

4. The validity period of the drug will be shortened after opening. Usually, the validity period of nitroglycerin tablets is 2 years, but once the drug packaging is opened, the validity period will be greatly shortened. Because the nature of nitroglycerin is unstable, it is more susceptible to the influence of external temperature and humidity after opening. The validity period will only last for 6 months at most. If it is in the hot summer, the remaining validity period may be even shorter.

Therefore, when you open the bottle for the first time, it is best to use a pen to record the time on the label, and use this to calculate the expiration date up to 6 months later. If you do not feel tingling, burning, or swelling in your head when taking the medicine sublingually, it means that the medicine may have expired.

5. Nitroglycerin tablets should not be used as a preventive medicine for angina pectoris. Some people take nitroglycerin as a meal, thinking that it can prevent the occurrence of angina pectoris. In fact, this practice is wrong. The reason why nitroglycerin can relieve angina pectoris is that after entering the human body, it can provide a large amount of nitric oxide (NO) to stimulate vasodilation.

However, the nitric oxide receptors in human blood vessels are limited. After repeated administration in a short period of time, the nitric oxide receptors will be exhausted and the efficacy will drop rapidly. If angina pectoris occurs at this time, taking nitroglycerin will not work. It will take a period of drug-free period (about 1 week) for the nitric oxide receptors to recover. Therefore, nitroglycerin tablets are only used to relieve acute symptoms and cannot be used as daily preventive drugs.

In summary, when using the "life-saving drug" nitroglycerin, patients with coronary heart disease need to be careful to avoid misunderstandings in medication to avoid drug ineffectiveness. The drug should be used under the guidance of a doctor. If you have any questions about the medication, please consult a doctor or pharmacist in time. I am pharmacist Huazi, welcome to follow me and share more health knowledge.