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Local anesthetics Surface (topical or mucosal) anesthetics • Bezocaine (Americaine, Anbesol, Chloraseptic, Num-Zit, Orajel) • Butamben (Butensin) • Cocaine • Dibucaine (Nupercainal) • Dyclonine (Dyclone, Sucrets) • Pramoxine (Anusol, Prame-Jel, ProctoFoam, Tronolane, Tronothane) • Proparacaine (Alcaine, Ocu-Caine, Ophthaine) Parenteral anesthetics • Articaine (Astracaine, Ultrcaine) • Bupivacaine (Marcaine, Sensorcaine) • Chloroprocaine (Nesacaine) • Etidocaine (Duranest) • Levobupivacaine (Chirocaine) • Lidocaine (Xylocaine, Dalcaine, Dilocaine , L-Caine, Octocaine) • Mepivacaine (Carbocaine, Polocaine) • Prilocaine (Citanest) • Procaine (Novocain) • Proparqacaine (Ophthaine, Alcaine) • Ropivacaine (Naropin) • Tetracaine (Pontocaine) Mechanism of action Works by blocking fast sodium channels in peripheral sensory nerve fibers and thereby preventing the pain-producing signals-or any sensory information from the affected are-from reaching the brain Surface anesthesia Applied as drops, sprays, lotions creams or ointment Used to eliminate gag reflex Local anesthetics administer by injection Infiltration anesthesia Refers to the superficial application of a local anesthetics Intravenous regional anesthesia (Bier’s Block) Used in surgery of the forearm and hand or foot and distal leg Nerve block anesthesia The injection of a local anesthesia along a nerve before it reaches the surgical site • Epidural anesthesia – administered outside the dura mater • Caudal anesthesia – for of epidural anesthesia achieve by administering local anesthetic into the base of the spine • Spinal anesthesia – achieved by injecting local anesthetics into the subarachnoid spaces between the arachnoid and pia mater membranes in the lumbar area • Saddle block – used principally in obstetrics for vaginal delivery Pharmacokinetics Enter systemic circulation and affects other organs, especially excitable tissues such as the brain and the heart Adverse reaction • Euphoria, anxiety, tingling (paresthesia), tremors and ringing in the ears (tinnitus) • Profound hypotension resulting to coma • Life cardiac threatening arrhythmia • Skin rashes (contact dermatitis) Inhaled anesthetics • Desflurane (Suprane) • Enflurane (Ethrane) • Halothane (Fluothane) • Isoflurane (Florane) • Nitrous oxide • Sevoflurane (Ultane) Mechanism of action Mechanism is still unknown, but believed that they effect on receptors of the inhibitory neurotransmitters GABA, produce classic state which includes analgesia, hypnosis, amnesia and depression of reflexes. Pharmacokinetics Inhaled anesthesia is a mixture of volatile liquids or gas and oxygen. When inhaled drugs are administered by mask, the gases flow into the mask through finely calibrated vaporizers. The amount of vapor the patient receives determines the depth of anesthesia. The distribution of the anesthetics is determined by the blood flow; thus the brain, liver and kidney reaches equilibrium first excretion is largely though the lungs. Emergence is the time during which the patient regains consciousness after the anesthetic has been discontinued Adverse reaction • Halothane and enflurane – reduces B/P as will as cardiac output • Desflurane and isoflurane - lower B/P but little effects on cardiac output • Respiratory depression, decrease ventilatory response to hypoxia, increase bleeding during D&C • Nitrous oxide –can cause blockage to the middle ear, pneumothorax loops of twisted intestine, renal cysts and the skull Intravenous anesthetics Barbiturate • Methohexital (Brevital) • Thiopental (penthothal) Benzodiazepines • Diazepam (valium) • Midazolam (versed) Opioids • Alfentail (alfenta) • Fentanyl (sublimaze) • Remifentanil (ultiva) • Sufentanil(sufenta) Others • Droperidol (inapsine) • Etomidate amidate) • Ketamine (ketalar) • Propofol (diprivan) Mechanism of action • Except for ketamine and the opioids are thought to produce an anesthetic-likestate primariry by increasing the effect of GABA – potential to depress vital functions conrolled by the brain. • Ketamine works by interfering with the action of glutamate which acts as an excitatory neurotransmitter. • Opioid actby stimulating receptors for opiates and opioid peptides in the CNS • It ca provoke profound analgesia but not actually anesthetic drug. Uses Primarily use for these drugs is in the induction of the anesthetic state, usually in short surgical procedures or where inhaled anesthetics will be employed for maintenance. Pharmacokinetics • The brain has a very high blood flow; a drug placed directly in the bloodstream will go first to the brain in high concentration • These drugs are very lipophilic so they easily cross the blood-brain barrier and enters the CNS Neuromuscular blocker Nondepolarizing • Antracurrium (tracrium) • Cisatracurium (nimbex) • Doxacurium (nuromax) • Mivacurium (mivacron) • Pancuronium (pavulon) • Pipecuronium (arduan) • Rocuronium (zemuron) • d-tubocurarine (turbarine) • vecuronium (norcuron) Depolarizing • Succinylcholine (anectine, quelicin, sucostrin) Mechanism of action Acts primarily as competitive antagonist at these receptors, thus preventing muscle contraction in response to motor nerve activity Uses Neuromuscular-blocking drugs provide muscle relaxation, particularly of the abdominal muscles, during surgery Also permits the use of a lower concentration of inhaled anesthetic, thereby reducing cardiovascular depression Pharmacokinetics Paralyzed patient must remain on artificial ventilation as long as a neuromuscular blocker is effective Adverse reaction • Triggers the release of histamines from mast cell • Alter cardiovascular function is by acting • At other cholinergic receptors found in the parasympathetic nervous system
