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 drug derives from the Greek word phármakon.

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

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


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 engineering 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, together with scientific research institutions, in addition to the chemical name of the active ingredient.

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 nomenclature of the same medicine.

The patents that are granted to the researcher who manages to invent a new drug, are guaranteed the unique 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 name 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 for the purpose of producing therapeutic benefits and minimizing the side effects that these can produce.

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 : They are used under strict medical control, that is why for sale they require a prescription signed by a doctor for sale.

Those that do not require a medical prescription: Its use can be considered safe, do not require medical control and are sold without the need to present a prescription.

Each country makes the decision of the drugs that request prescription and which 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 biochemical reactions of the body, 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 the use of 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 to infer what physiological or functional changes are going to occur as a pharmacological response in the organism.

Adverse reactions

The drug is considered ideal to those who immediately achieve with precision, reach the focus of the disease without hurting the tissues that are in good condition.

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

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

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