Anesthetic drug, as a rule, is used in dental practice and other branches of medicine. Without painkillers, it is impossible to carry out surgery and other drug manipulations. This group of drugs has several types. It should also be noted that some patients are allergic to pain medications.
In order to analgesize a specific area of soft tissues, local anesthetics are used. They well reduce the stimulation of sensitive nerve endings. As a rule, such medicines are used in dental practice. It should be noted that the first anesthetic was Cocaine. It was used in different forms for local and general anesthesia.
Basically, an analgesic for local anesthesia is used in the form of injections. One of the most popular medicines of this group is considered to be "Lidocaine". Not so strong and toxic is Prilocaine.
Generations of anesthesia drugs
For anesthesia, you can use drugs in various ways. In pharmacology, the classification of local anesthetics for use will be as follows:
- Inhalation products - Sevoran, Propofol, Diprivan, Fluorotan, Ether. Such anesthetics help to relax skeletal muscle, suppress pain. In this case, a person loses consciousness for a while.
- Intravenous preparations - Ketamine, Hexanal, Fentanyl, Relanium, Seduxen, Droperidol, Sodium Oxybutyrate. These medicines have a quick effect. The patient loses consciousness after about twenty minutes.
Before use, the doctor should exclude the presence of allergic reactions in the patient to a specific component.
Requirements for anesthetics
Any drug has certain requirements that it must meet. Here is some of them:
- The presence of increased selectivity of action.
- Such drugs should have a resorptive effect. This reduces the likelihood of side effects.
- No annoying effect.
- An analgesic drug should act instantly and for a long time.
- Medicines must be soluble and not susceptible to degradation during sterilization and storage.
It is possible to produce anesthesia only with those drugs that correspond to all of the above items.
Pharmacology: classification of local anesthetics
All groups of drugs need to be classified. Medications for superficial analgesia are called local. They inhibit the sensitivity of nerve endings in a specific part of the body. In this case, the patient is conscious. Local anesthetics:
- "Lidocaine".
- Dikain.
- "Anestezin".
- "Pyromecain".
This type of anesthetic partially blocks and weakens the nerve endings. In this regard, it is used only locally, as a rule, in dentistry. What is the mechanism of action of local anesthetics?
Duration classification
This is important to consider when planning an operation. Anesthetic drug has a different degree of action. Classification of local anesthetics:
- Short-acting - up to 30-50 minutes - Novocain.
- The average duration of action - up to 45-90 min - "Mepivacaine", "Lidocaine".
- Long-term action - up to 90 minutes or more - Bupivacaine.
It should be noted that the stronger the anesthetic, the more toxic it is.
"Artikain", as well as "Lidocaine", "Mepivacaine" - the hydrolysis of these drugs is going well, the effect comes quickly (after five minutes, depending on the method of anesthesia.
These painkillers are considered weak bases, they are poorly soluble in water, used in the form of water-soluble salts, which are convenient for use. For the local anesthetic effect to manifest in the tissues at the injection site, solvolysis with water should be carried out with the formation of an anesthetic drug that is readily soluble in lipids.
There is a classification of local anesthetics by chemical structure. This will be discussed later.
What is included
The structure of painkillers includes the following:
- anesthetic
- vasoconstrictor;
- additives;
- preservative;
- vasoconstrictor stabilizer.
The chemical classification of local anesthetics according to the structure distinguish:
Esters - Novocain, Dikain, Anestezin.
Amides - Atrikain, Lidocaine, Metevacaine, Prilocaine, Trimecaine, Bupivacaine, Etidocaine.
A vasoconstrictor is needed to enhance the influence of the anesthetic. An additional component is sulfate and sodium edetate. Methylparaben has a preservative role.
Pharmacological properties
The mechanism of action of local anesthetics is based on a violation of nerve sensitivity. Anesthesia blocks pain. It is important to note that the effect of the drug depends on its solubility in water and fats.
General anesthesia is a strong anesthesia, due to which the body completely loses pain sensitivity and reflexes for a period of time. In this case, the skeletal muscles are relaxed. Its use is possible only with complex and painful surgical interventions.
When anesthetics are used
Locally prescribed painkillers in the form of superficial and injection. The first type of anesthesia is carried out by applying to the mucous membrane or wound. As a rule, in such situations, "Benzocaine" and "Lidocaine" are used. Such anesthetic medicines are also used to block various inflammatory processes, as well as infections and neurological diseases.
Dentists do not use large doses of anesthesia. For surface anesthesia use creams, as well as gels, ointments and solutions. There is a large list of painkillers that dentists use. The doctor should choose a safe medicine that will not cause allergies.
Indications for general and local anesthesia:
- Any surgical interventions.
- Catheterization (a type of instrumental examination often used to diagnose and treat bladder pathologies).
- Probing (a method for examining the gastrointestinal tract, diagnostic procedure).
- Intubation (ensuring normal airway patency by introducing a special tube into the trachea).
- Osteosynthesis (surgical reposition of bone fragments with the help of various fixing structures, ensuring the long-term elimination of their mobility).
- Neurological blockade (a medical procedure to relieve muscle cramps).
- Spinal anesthesia (anesthesia method in which a blocking agent is injected directly into the cerebrospinal fluid).
Such anesthesia is usually used when brushing a canal. The classification of local anesthetics in dentistry is no different from the usual classification of these drugs. The following tools are used:
- Ultracaine.
- "Ubistezin."
- "Septanest".
- "Scandonest."
Contraindications and adverse reactions
Therapy with anesthetic is carried out only after the exclusion of prohibitions on use. Local anesthesia is contraindicated in the presence of the following conditions:
- Surgery for obesity.
- Operations in violation of gas exchange.
- An allergic symptom.
- Violation of the psyche, pathology of the auditory apparatus, a state of severe intoxication.
- The patient is unconscious.
- Epilepsy (a chronic neurological disease, manifested in the predisposition of the body to the sudden onset of convulsive attacks).
- Panic condition of the patient, refusal of local anesthesia.
- Children under the age of ten.
- Sepsis (a serious infectious disease that develops with the progression and spread of the infectious process through the body through the blood).
- Hemorrhagic symptom (tendency to increased bleeding of the skin, mucous membranes and internal organs due to pathology of the hemostatic system).
- Anemia (a group of clinical and hematological syndromes, the common point for which is a decrease in hemoglobin concentration in the blood, more often with a simultaneous decrease in the number of red blood cells).
- Heart failure.
The local anesthesia in dental practice, the doctor must select individually. You can apply such an anesthetic during lactation. Adverse reactions of anesthetics, as a rule, appear due to improper use.
In most situations, the following negative effects appear:
- Tachycardia (increased heart rate (HR) from 90 beats per minute).
- Fainting.
- Edema at the injection site.
- Congestion in the ears.
- Anaphylaxis (an allergic reaction of an immediate type, a state of sharply increased sensitivity of the body).
In addition, such symptoms can occur when an allergy appears.
Complications
Local anesthesia requires some experience and compliance with all the rules. Various factors can provoke complications, which the doctor allows in the process of anesthesia. These include:
- Damage to soft tissue with a needle or injection.
- Cracking injection needle.
- Pain syndrome.
- Paresthesia (one of the types of sensitivity disorder, characterized by spontaneously arising sensations of burning, tingling, crawling ants).
- Trismus (tonic spasm of the masticatory muscles, leading to restriction of movements in the temporomandibular joint).
- Hematoma.
- The development of infection.
- Necrosis (a pathological process manifested in local tissue death in a living organism as a result of some exogenous or endogenous damage to it).
- Paresis of the facial nerve (a neurological disease characterized by weak facial muscles).
- Allergic manifestations.
- Toxic reaction.
- Emotional stress due to fear of pain.
Each person may have different complications after the administration of an anesthetic. In this connection, before using the medicine, if the patient has an allergic reaction, this should be reported to a medical specialist.
Anesthetics also have certain disadvantages, for example:
- Neurotoxicity.
- Cardiotoxicity
Anesthetic in any situation causes toxicity. It all depends on the dosage and the anesthesia group that is used. Neurotoxicity may occur in the form of:
- Violations of motor and sensory functions.
- Emotional stress.
- Integrative brain functions (total or partial loss of memory).
- Visual and hearing impairment.
- Muscle weakness.
- Paresis (neurological syndrome, decreased strength due to damage to the motor path of the nervous system).
- Paralysis (complete absence of voluntary movements, due to the same reasons as in the case of paresis).
One of the most severe consequences of local anesthesia in dental practice is facial paresis.
Local anesthetic provokes cardiotoxicity only with an overdose. This complication is extremely rare. At the same time, the conduction of nerve impulses and the expansion of capillaries are reduced.
What to do if allergies occur
The effect of painkillers on the human body in most cases is accompanied by the occurrence of allergic manifestations. But not all anesthetics can provoke a similar reaction.
Before anesthesia, an analysis should be done to exclude intolerance or allergy to a particular drug. After that, the medical professional will use safe pain medication.
Before doing anesthesia, you need to carry out a list of samples to exclude allergic reactions. A blood test to detect negative reactions to an anesthetic in this situation is not considered effective.
Lidocaine
The drug is used for conduction, as well as infiltration and terminal anesthesia. Anesthetic has a local anesthetic and antiarrhythmic effect. As an anesthetic, it works by suppressing nerve conduction by blocking sodium channels in nerve fibers and endings.
The medicine is significantly superior to Procaine, its effect is faster and longer - up to 75 minutes (together with Epinephrine - more than two hours). When used locally, the anesthetic dilates the capillaries; it does not exert a local irritant effect.
The antiarrhythmic effect of the drug is due to the ability to increase the permeability of membranes for potassium, block sodium channels, and stabilize cell membranes. "Lidocaine" has no significant effect on contractility, myocardial conductivity (affects only in large doses).
The level of absorption of "Lidocaine" with topical administration depends on the dosage of the drug and the place of processing. After intramuscular injections, the maximum content is reached after five to fifteen minutes after application.
"Benzocaine"
The active ingredient has an analgesic effect, preventing the development of pain. With external use and application to the mucous membranes, the effect of "Benzocaine" occurs immediately and lasts for fifteen to twenty minutes.
Benzocaine is a widespread local anesthetic. The solution is produced as a part of medicines for local use or for oral use.
The drug is a white powder that does not have a specific aroma, but has a bitter taste. If you apply the drug to the tip of the tongue, you will feel numb.
When using the drug, a minimum of the active component is absorbed locally and orally. After applying the drug to the mucous membrane, the action of "Benzocaine" occurs after only one minute and lasts up to twenty minutes.
"Novocaine"
The active component of the injection solution has a local anesthetic effect, it leads to a decrease in all types of tissue sensitivity in the field of application. The pharmacological effect occurs due to the blocking of the sodium channels of the walls of the peripheral nerves, which prevents the conduction of a nerve impulse in sensitive tissues.
After absorption of procaine (active substance) into the general bloodstream, it blocks the transmission of impulses in the autonomic ganglia, and also reduces the excitability of peripheral cholinergic structures of the central nervous system. In addition, the anesthetic reduces muscle spasm, reduces the excitability of the motor structures of the cerebral cortex and heart muscles.
The duration of action from the solution for injections "Novocaine" is low and ranges from thirty minutes to half an hour.
After the drug is introduced into the tissue, the active component accumulates in the injection area, and then is absorbed into the systemic circulation. The absorption rate depends on the area of application of the medication. The active substance in the liver is exchanged with the formation of inactive decay products, which are eliminated from the body with urine. The withdrawal time of half the entire dosage of the drug after absorption of the drug is fifty seconds.