What is a drug ?: Types, Nomenclature, Presentation, Medical Prescription, Therapeutic Action and Adverse Reactions

It produces a modification in the biological operation of the organism, from its chemical actions, changing the cellular dynamism.

A drug is an active, synthetic, or natural substance used for preventive or therapeutic diagnostic purposes. The word medicine derives from the Greek word phármakon.

When used in the prevention, relief, healing of disease, and repair of its sequelae, it causes a functional or anatomical effect in the patient.

The active principle is the component that possesses toxic or pharmacological properties.


They are classified in:

  • Natural
  • Synthetics

For example, when it is a substance identical to those produced by the human body and obtained thanks to genetic engineerings, such as hormones are natural drugs.

They can also be chemical substances that do not exist in nature, and that are obtained through the synthesis of chemical compounds.



Drugs are assigned a generic name by the manufacturer of pharmaceutical products, scientific research institutions, and the active ingredient’s chemical name.

Now, if the merchant distributes it with a name that is patented, this may vary according to the name assigned by the company and the country where it is distributed, and this has created a varied vocabulary of the same medicine.

The patents granted to the researcher who manages to invent a new drug are guaranteed the individual rights of his patent, considering that the medicine belongs to the owner of the same.

Once the time granted in the patent expires, the industries or an authorized distributor can legally commercialize the medication with its generic name, and the company that patented it continues to be the owner of the commercialized name.

Each drug can have three names in its presentation:

  • A chemical name: Refers to the atomic or molecular structure of the drug.
  • A character without patent (generic): Assigned by an official health agency.
  • A registered name or commercially patented: Assigned by the pharmaceutical company, usually linked to the drug.


There are various pharmaceutical forms in which they present and market the medicines, and this is to produce therapeutic benefits and minimize the side effects that these can have.

There are presentations:

  • Liquids: Sprays, syrups, eye drops, among others.
  • Solid: powders, granules, dragees, pills, among others.
  • Semisolids: Pastes, cream, ointment, suppositories, among others.

Medical prescription

According to legal classifications, there are two types of drugs:

Those that require a medical prescription are used under strict medical control; they need a prescription signed by a doctor for sale.

Those that do not require a medical prescription: Its use can be considered safe, does not require medical control and is sold without presenting a prescription.

Each country decides on the drugs that request prescription and can be sold freely.

The official health entity consents to the commercialization without a prescription of a drug in case it is proven that its use over time is innocuous.

Therapeutic action

The drugs only affect the compass of the biological functions; they can alter, hasten or delay the body’s biochemical reactions, the nervous transmission, the glandular secretion of gastric acid, mucosa, and insulin.

The activity of drugs depends on the response of the processes or functions to which the medication is directed.

Pharmacological response

All individuals respond differently to medications.

The dose to obtain an adequate response to medications is related to weight, metabolism, and the suffering of other diseases.

According to the chemical composition of the drugs, they can be dosed accurately and achieve the desired effects.

The chemical composition allows us to infer what physiological or functional changes will occur as a pharmacological response in the organism.

Adverse reactions

The drug is considered ideal for those who immediately achieve with precision and reach the focus of the disease without hurting the tissues in good condition.

Therefore, the objective of research in creating new drugs is to achieve maximum selectivity.

But while drugs fight diseases in the same way, they can produce some non-secondary effects called adverse reactions.

The action of a drug is termed the desired effect or side effect according to the reason the drug is administered and the reaction it produces.