What is the noun explanation of "drug"?

Drugs are substances used to prevent, treat and diagnose diseases. In theory, drugs refer to all chemicals that can affect the physiological functions of organs and cell metabolism activities, which belong to the category of drugs, including contraceptives.

According to the law and international classification management, drugs are divided into two categories: prescription drugs and over-the-counter drugs (OTC). Prescribed drugs refer to those drugs that can only be used under medical supervision in consideration of medical safety, and must be prescribed in writing by a medical practitioner (such as a physician, dentist or veterinarian). Over-the-counter drugs refer to those drugs that are quite safe without medical supervision and can be sold directly by pharmacies without prescription.

Extended information:

Drugs, whether drugs or recreational drugs, can be administered in many ways. Many drugs are administered in more than one way.

1. Rapid bolus injection is one of the ways of administration, which enables drugs or other compounds to reach an effective concentration level in the blood. Push injection can be done intravenously, intramuscularly, intrathecally or subcutaneously.

2. Inhalation (breathing into the lungs), usually aerosol or dry powder (including inhaled substances).

3. Inject suspension or emulsion by intramuscular injection (intramuscular injection), intravenous injection (intravenous injection, which is divided into intravenous drip and intravenous injection), intraperitoneal injection and intraosseous injection.

4. Spray, or spray into the nasal cavity.

5, oral liquid or solid, through the intestinal absorption.

6. Rectal suppository is absorbed through rectum or colon.

7. Take it under the tongue and spread it into the blood through the sublingual tissue.

8. External use, usually cream or ointment, can be administered locally or systemically.

9. Vaginal suppository is mainly used to treat vaginal infection.

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