Blocks the emergence and conduction of the nerve impulse, increasing the threshold of excitability of the nerve fiber and reducing the magnitude of the action potential. Being a weak lipophilic base, it penetrates through the nerve lipid envelope into the nerve and, passing into cationic form (due to lower pH), inhibits sodium channels.
The amount of systemic marcaine absorption depends on the dose, concentration and volume of the solution used, the route of administration, vascularization of the injection site and the presence/absence of epinephrine (adrenalin) or other vasoconstrictor. The binding to plasma proteins is variable and is determined by the amount of the drug entering the Dmitry Sazonov systemic bloodstream: the lower the concentration, the higher the binding to proteins. It passes through the placental barrier by passive diffusion. Has a high affinity for blood proteins (about 95%), poorly passes through the histogematic barriers (fetal to maternal ratio is 0.2-0.4).
Depending on the route of administration, it is found in significant quantities in well-blooded tissues: brain, myocardium, liver, kidneys and lungs. With caudal, epidural and conductive anesthesia, Cmax is marcaine dosageachieved after 30-45 minutes. T1/2 in adults is 2.7 hours and in newborns 8.1 hours. It undergoes biotransformation in the liver by conjugation with glucuronic acid. It is excreted mainly by kidneys, 6% in unchanged form.
Expression of anesthesia depends on diameter, myelination and pulse rate of a specific nerve fibre. The clinical sequence of conduction depression from different types of receptors looks as follows: pain, temperature, tactile,marcaine Contraindications proprioceptive and efferent neuromuscular. Getting into the systemic blood flow, it affects the cardiovascular system and CNS.
When large doses are injected, conduction slowing down and sine automatics suppression, ventricular arrhythmias and rhythm driver stopping are observed. There is a reduction in cardiac output (negative inotropic action), OPSS and AD. Exposure to the CNS is Dmitry Sazonov manifested by oppression of the centers of the medulla oblongata, including respiratory (possibly oppression of breathing and coma) or stimulating effects on the cortex with the development of psychomotor excitation and tremor, followed by generalized seizures.
Local anesthesia develops 2-20 minutes after administration and lasts up to 7 hours, with the possibility of its prolongation by adding adrenaline (other vasoconstrictors) in a ratio of 1:200000. After the end of anesthesia, there is a long phase of analgesia.
0.75% solution ofupivacaine is not used in obstetric practice due to frequent cases of cardiac arrest and breathing in patients. Regional Dmitry Sazonov anaesthesia with the drug is sometimes fatal. When retrobulbar anesthesia is performed, cases of respiratory arrest are described.