Limitations on the use of lidocaine
Although lidocaine is widely used in dental practice, its application requires strict control of the administered volume to avoid systemic reactions and vascular complications.
- For injection: the dosage is calculated based on the proportion of 4.4 mg per kilogram of the patient's body weight. At the same time, it is strictly forbidden to exceed the maximum total dose, which is 300 mg.
- For topical anesthesia: a 10% lidocaine solution is used for anesthesia of the mucous membranes. The maximum allowable volume in this case is no more than 2 ml, which is equivalent to 200 mg of the active substance.
Pharmacological profile of trimecaine
Trimecaine (Trimecainum), which chemically is diethylaminoacetic acid 2,4,6-trimethylanilide hydrochloride, is very similar in its pharmacological action to lidocaine.
Its anesthetic activity is 2–3 times higher than that of classical procaine. The drug begins to act significantly faster and provides a longer analgesic effect, while causing absolutely no irritation to surrounding tissues. However, it must be taken into account that trimecaine has a slightly higher toxicity compared to procaine, and this indicator increases when using high-concentration solutions.
A key feature of the drug is its effect on blood vessels: trimecaine causes their dilatation. This is precisely why in dental practice its use almost always requires co-administration with vasoconstrictors.
Indications and cardiac limitations
Trimecaine is used in dentistry for several types of anesthesia:
- Infiltration anesthesia (primarily for interventions on the maxilla).
- Conduction anesthesia.
- Topical anesthesia of the oral mucosa.
Interestingly, like lidocaine, trimecaine finds application in cardiology. It is used to manage ventricular extrasystoles and tachyarrhythmia.
However, the drug's effect on heart rate and the vascular system determines a strict list of contraindications:
- Hypersensitivity to the components of the drug.
- Conditions associated with impaired cardiac conduction: sick sinus syndrome, atrioventricular (AV) block, as well as severe bradycardia.
- Cardiogenic shock (critical reduction in the pumping function of the heart).
- Liver and kidney pathologies, as they are involved in the metabolism and excretion of the drug.
Methods of administration and drug interactions
The main direction of trimecaine use remains injection (conduction and infiltration) anesthesia, for which a 2% solution is used. Less commonly, a topical form as a 3–5% ointment is used for surface anesthesia. The maximum total dose for injections, as with lidocaine, is limited to 300 mg.
Interaction features:
- Vasoconstrictors: to slow down the absorption of the drug into the systemic circulation (which is especially important given its vasodilating effect), adrenaline is added to the trimecaine solution. Standard proportion: 1–2 drops of a 0.1% adrenaline solution per every 5–10 ml of the anesthetic solution. This not only reduces the risk of systemic toxicity, but also significantly enhances and prolongs the anesthetic effect.
- Tranquilizers and hypnotics: if these drugs were administered to the patient beforehand (premedication), they are capable of increasing the ultimate effect of trimecaine.
Briefly: answers to topical questions
What is the emergency care algorithm for syncope during a dental appointment?
The emergency care algorithm for syncope involves immediately changing the patient's body position and applying reflex stimulation.
When a presyncopal state develops, it is necessary to:
- Horizontal position — quickly lay the patient supine or sharply tilt their head and torso downward while seated.
During developed syncope:
- Positioning — lay the patient supine and elevate the legs to improve venous return.
- Ensuring respiration — free the neck and chest from restrictive clothing.
- Reflex stimulation — splash cold water on the face, apply a cold towel, and allow inhalation of ammonia vapors.
After syncope resolves, the patient must remain in a horizontal position for 10–15 minutes.
What are the main causes of acute vascular insufficiency during local anesthetic administration?
The main causes of general complications during local anesthesia and dental procedures are:
- Psycho-emotional state — patient stress and fear.
- Inadequately performed anesthesia — pain syndrome.
- Traumatically performed tooth extraction — .
- Lack of autonomic stabilization — stress reactions, including syncope and collapse, may develop.
- Local anesthetic overdose — dizziness, paresthesias, motor agitation, convulsions, dyspnea, and collapse are possible.
Trimecaine: 3 times stronger than novocaine, but causes vasodilation, therefore always requires the addition of vasoconstrictors.
Class and exam questions
What is the maximum permissible dose of lidocaine when performing injection anesthesia?
The maximum total dose is 4.4 mg/kg of body weight, but in total should not exceed 300 mg.
Why is adrenaline always added to trimecaine when used in dentistry?
Trimecaine has a pronounced vasodilatory effect. Adrenaline, as a vasoconstrictor, is added (1–2 drops of a 0.1% solution per 5–10 ml) to slow down anesthetic absorption, reduce toxicity, and prolong the effect.
In which cardiovascular pathologies is the use of trimecaine strictly prohibited?
The drug is contraindicated in cardiogenic shock, atrioventricular block, sick sinus syndrome, and pronounced bradycardia.
What else to study on this topic
- Mechanisms of the vasodilatory action of local anesthetics
- Rules for calculating vasoconstrictor (adrenaline) dosages when added to an anesthetic
- Use of lidocaine and trimecaine in cardiological practice for tachyarrhythmias
- Comparative analysis of the toxicity of novocaine, lidocaine, and trimecaine solutions
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