There are many different ways to introduce a drug into the human body. The first at the dawn of medicine, local methods were applied in the form of applications, rubbing, compresses and oral, including swallowing a number of dosage forms or sublingual resorption. With the development of medicine and technology for the delivery of the active substance to the target organ, more complex methods began to be used.
Rectal and vaginal suppositories (suppositories), multicomponent tablets and capsules, including coated tablets, dissolved either by gastric juice or intestinal enzymes, appeared. Injection methods: intra- and subcutaneous, intramuscular, intravenous and intra-arterial, intraosseous. Drugs are injected into the joints and into the organs.
Despite the fairly simple route of administration, endotracheal and intranasal drugs have been used relatively recently. Of course, nose drops already existed under Hippocrates. However, intranasal is like one of the methods of administering the drug for delivery to other organs, and not an anti-edema remedy for the common cold, and such an introduction began to be applied only several decades ago.
Groups of intranasal drugs that have a general (systemic) effect
Numerous studies have revealed that the fight against the common cold is not the only reason for the introduction of the drug into the nasal cavity. A number of drugs that have a systemic effect are completely absorbed from the mucous membrane of the nasal passages and reach their intended purpose.
Intranasal administration is possible for:
- H1-antihistamines (anti-allergic);
- a-adrenergic agonists (vasoconstrictors);
- mast cell membrane stabilizers;
- serotonergic (having various effects - from vasoconstriction to antiallergic);
- hormonal and anti-hormonal;
- narcotic analgesics ;
- immunomodulators;
- cartilage and bone tissue metabolism correctors;
- psychostimulants and nootropics.
Features of intranasal administration of drugs
For quite some time, pharmaceutical companies tried to solve two unsolvable problems regarding the use of drugs with a protein chemical structure. The stumbling block was the destruction of the protein-peptide component of the active substance by gastric juice and intestinal enzymes when taken orally. Also a problem was the phenomenon of the first passage through the liver - the binding of the active complex and its excretion.
The solution was found in the use of an injectable route of administration and rectal suppositories. However, the first way is characterized by some technical complexity in combination with unpleasant sensations. And the second turned out to be insufficiently effective due to low absorption in the final sections of the rectum. The decision came unexpectedly. It turned out that the intranasal is, like injection, such an introduction in which a rapid onset of the therapeutic effect is achieved. And with the addition of certain concomitant substances, the same high bioavailability is ensured, that is, the necessary concentration of the active ingredient in the place of its use.
Another useful property of intranasal administration was manifested in extracellular (bypassing absorption into the blood through the mucous membrane) penetration of active substances into the brain. Once in the olfactory zone, the drug is delivered through the fibers of the olfactory and trigeminal nerves.
Forms of release of intranasal preparations
For the introduction into the nasal cavity, a fairly limited number of pharmacological forms are used. First of all, this, of course, drops in the nose. Inhalation of powders with a finely divided structure is possible. The laying of ointments is used. Various solutions or decoctions of herbs for washing the nasal cavities do not belong to this group due to the short exposure to the mucosa during their use.
The main form of release of intranasal drugs with a systemic effect are nasal sprays. They are available in the form of spray cans with compressed air or with an active spray pump. Due to a certain amount of spray release when pressed once, there is the possibility of a relatively controlled dosage of the drug.
Also, when using a spray, uniform irrigation of the nasal mucosa occurs. This contributes to a more complete absorption of the drug, which increases its pharmacological effect.
The main advantages of intranasal administration
Based on the foregoing, it is possible to determine the key advantages that intranasal drugs possess. The ease and ease of administration, which does not require additional technical equipment and special training, as in the case of injection methods, are quite significant from the side of their use by the patient.
From the standpoint of physiology and pharmacology, the possibility of a central action on the structures of the brain comes first. A pronounced systemic effect that occurs in a short time, as with the injection method of administration, is also of great importance. Due to the absence of the phenomenon of the first passage through the liver, a high bioavailability of the drug and a small amount of undesirable reactions associated with it are ensured.
The disadvantages of the method
From the point of view of the systemic effect, the main problem is maintaining the level of therapeutic concentration of the drug in blood plasma. The drug is rapidly absorbed and reaches a peak effect in a short time, so intranasal administration can only be used for short-term correction of conditions. A prolonged effect is possible only with the introduction of drugs that have an effect on the structure of the brain.
In addition, the development of local reactions on the nasal mucosa is possible. This is due to a sufficiently high concentration of the active substance in the composition of the spray and the content of additional components that ensure the maximum passage of the drug from the surface of the mucosa into the blood.
The possibility of absorption from the nasal cavity has a fairly limited number of drugs that have the necessary physical and chemical properties. In a patient, an increased concentration of the active substance leads to significant costs for the acquisition of a spray.
Intranasal immunomodulators
In the off-season or in the conditions of epidemics of colds, for the prevention and treatment, drugs are widely used that increase the general and local immune defense of the body.
For the purpose of emergency prevention and protection, intranasal interferon is used.
In multiple studies, it was found that the intranasal route of administration of immunomodulators contributes not only to preventing the penetration of pathogen viruses through the nasal mucosa. It also stimulates the work of their own defenses - activation of the production of their own interferons. To stimulate the production of endogenous interferon as a means of maintenance therapy, the drug Anandin intranasal is used.
Human interferon
The drug is a specific immune defense, having activity against most causative agents of viral colds, "Interferon" is available in the form of tablets, injectables and powders for the preparation of drops. For prevention and treatment, you can use any form of release. But to provide local protection, preferably intranasal. This, as an invisible barrier, will prevent the penetration of a significant amount of viruses into the cells of the mucous membrane of the nasal cavity. This will provide a lower incidence in an epidemic.
Immunostimulant "Anandin", eye drops and intranasal
The drug was widely distributed due to the almost complete absence of side effects, adverse reactions and a good immunostimulating effect. In addition to this, it also has a pronounced wound healing property, which is important when used in the form of eye drops for injuries to the cornea or conjunctiva.
Contraindications to use is only administered intramuscularly "Anandin". Intranasal drops are allowed at any age, during pregnancy, lactation and other physiological conditions or diseases.
If a runny nose is allergic
Often the cause of itching in the nose, sneezing and copious mucus is not the virus, but the antigen, which leads to a nonspecific immune response - an allergy. In the complex treatment of this form of rhinitis, intranasal corticosteroids are often used. This is especially true for people suffering from seasonal forms of allergies - hay fever.
During the flowering period of certain plants, it is not enough for such patients to use only antihistamine drugs, which in most cases also have a sedative effect. This is not permissible when driving, working with machinery, or in conditions of maximum mental concentration. Then local hormonal sprays are prescribed, which relieve the onset of symptoms, without significantly affecting the general hormonal background.
Precautionary measures
Despite the wide availability and easy tolerance of such drugs, it is important to remember that intranasal is, like any other, a drug that should be used exclusively as prescribed by the doctor, in the dosage prescribed by him, the frequency and duration of administration.
Often there are situations when you need to take several drugs at once, none of which can be canceled. Therefore, it will be necessary to find out if they will not have a negative effect on the body when combined. Instructions for use may not include all options for the development of an allergic reaction. That is why before taking such common drugs as suppositories, ointments and sprays, you should definitely consult a specialist.