Anesthesia Drugs

Muscle Relaxants Succinylcholine Action: Rapidly binds to Acetylcholine receptors and cause sustained depolarization of muscle fiber Indication: Quick onset 30-60s; Fast duration of action 5-10m Contraindication: Hyperkalemia, Bradycardia (esp. in peds); Fasiculations (w/ myalgia, Increased (ICP, IOP, IGP), trigger for Malignant Hyperthermia (MH), no reversal agent Unique Characteristics: Only depolarizing Muscle Relaxant Rocuronium Action: Direct antagonism of Ach receptor sites, thereby preventing depolarization Indication: rapid onset 1-2m; duration 20- 35 minutes Contraindication: Renal failure (30% renal excretion) results in longer duration. Unique Characteristics: No Cardiovascular effects or histamine release following rapid admin even at large doses. Vecuronium Action: Direct antagonism of Ach receptor sites, thereby preventing depolarization Indication: Onset 3-5m, duration of action 20-35m Contraindication: Unique Characteristics: Lack of vagolytic effects or associated histamine release Pancuronium Action: Direct antagonism of Ach receptor sites, thereby preventing depolarization Indication: Onset 3-5m; duration 60-90m Contraindication: Atropine-like effects, Coronary artery disease, Afib; Renal failure Unique Characteristics: Long-acting nondepolarizing NMBD Cistracurium Action: Direct antagonism of Ach receptor sites, thereby preventing depolarization Indication: Onset 3-5m, duration 20-30m; Organ dependent clearance (hofmann elimination) can be given to renal of hepatic patients). Contraindication: Unique Characteristics: Devoid of histamine-releasing effects Reversal Agents Edorphonium Action: Irreversibly bind to acetylcholinesterase (AchE), thereby preventing the hydrolysis of Ach and increasing the Ach concentration in the NMJ Indication: Nicotinic benefits Contraindication: Muscarinic side effects: Bradycardia, Enhanced gastric fluid secretion, Hyperperistalsis (nausea & vomiting), Miosis, Salivation Unique Characteristics:

Neostigmine Action: Irreversibly bind to acetylcholinesterase (AchE), thereby preventing the hydrolysis of Ach and increasing the Ach concentration in the NMJ Indication: Nicotinic benefits Contraindication: Muscarinic side effects: Bradycardia, Enhanced gastric fluid secretion, Hyperperistalsis (nausea & vomiting), Miosis, Salivation Unique Characteristics: Most commonly used. Maximum dose 60-70 um/kg Atropoine Action:

Competitive antagonism of Ach at cholinergic post-ganglionic muscarinic receptor sites Indication: Neostigmine or endrophonium; given prior to anitcholinesterase drugs to attenuate muscarinic effects Contraindication: Unique Characteristics: Anticholinergic Glycopyrrolate Action: Competitive antagonism of Ach at cholinergic post-ganglionic muscarinic receptor sites Indication: Neostigmine; given prior to anitcholinesterase drugs to attenuate muscarinic effects. Contraindication: Endrophonium Unique Characteristics: Anticholinergic Phenylephrine Action: α1 direct receptor agonist, peripheral vasoconstriction (↑SVR) Indication: Low blood pressure Contraindication: Bradycardia with low CO Unique Characteristics: Epinephrine Action: α1, α2, β1, β2 direct receptor agonist causing: bronchodilation, chronotropy, inotropy, vasoconstriction Indication treatment of decreased inotropy and chronotropy, conjuction w/ LA’s, relief of hypersensitivity reactions, restore cardiac rhythm in cardiac arrest paients, Contraindication: Hand and foot surgeries, tachycardia Unique Characteristics: Has most significant effects on metabolism Ephedrine Action:Indirect receptor agonist simulating norepinephrine release. Vasoconstriction, chronotropy Indication: Anesthesia-induced hypotension in pregnant women Contraindication: Tachyphylaxis, cardiac dysrhythmias (esp w/ Unique Characteristics:

Norepinephrine Action: α1, α2, β1 direct receptor agonist. Intense vasoconstriction and mild inotropy Indication: Profound systemic hypotension during shock or refractory hypotension Contraindication: Unique Characteristics: Labetalol Action:

Antihypertensive blocks α1 receptors selectively and β-receptors nonselectively. Indication: Sudden increase in chronotropy and systematic bp due to surgical stimulation. Contraindication: Asthmatics ( Bronchospasm) and preexisting cardiac dysfunction (CHF) Unique Characteristics: Abrupt discontinuation may precipitate withdrawal. Esmolol Action: short acting β1 direct selective receptor antagonist Indication: Tachycardia and tachy-arrhythmias w/ narrow QRS’s Contraindication: pre-excitaion syndrome; bradicarida Unique Characteristics: can be used to blunt the hemodynamic response to intubation in ESRD patients Metoprolol Action: β1 direct selective receptor antagonist, Indication: Sustained tachycardia w/ narrow QRS’s Contraindication: pre-excitaion syndrome; bradicarida Unique Characteristics: Lidocaine Action:

Prevent impulse transmission along nerve by selectively preventing ionic movement across Na+ channels. Rate of depolarization is slowed to the point where action potential cannot be reachedhepatic metabolism Liver dx. & ↓hepatic blood flow ↑toxicity. Indication: Can produce anesthesia w/o loss of consciousness. Local topical , regional IV, peripheral nerve block, spinal and epidural anwsthesia. Contraindication: potential neurotoxicity(cauda equine syndrome) TNS. Maximum dose 4 mg/kg (7 mg/kg w/ epi) Unique Characteristics: The first “amide” LA (1943). Most commonly used and versatile anestetic Action: Indication: Contraindication: Unique Characteristics: