Anesthesia/anesthetics parenteral

Amide-type agents include articaine, lidocaine, bupivacaine, prilocaine, mepivacain and ropiva-caine. These are metabolized in the liver by microsomal enzymes with amidase activity. The amide group is preferred for parenteral and local use. If by accident rapidly administered intravascularly these agents, especially bupivacaine but also lidocaine, can produce serious and potentially lethal adverse effects including convulsions and cardiac arrest. They can more easily accumulate after multiple administrations. Intravenous lidocaine is sometimes used for regional anesthesia, for infiltration procedures, for the induction of nerve blockade and for epidural anesthesia. However, it is also used as an antiarrhythmic. Bupivacaine is a long-acting local anesthetic used for peripheral nerve blocks and epidural anesthesia. 

The lungs are important for the excretion of volatile drugs. As a result of reduced respiratory capacity (Figure 61-1) and the increased incidence of active pulmonary disease in the elderly, the use of inhalation anesthesia is less common and parenteral agents more common in this age group. (See Chapter 25 General Anesthetics.)... 

DOT CLASSIFICATION Forbidden SAFETY PROFILE A human poison by ingestion and possibly other routes. Poison experimentally by ingestion, intraperitoneal, intravenous, subcutaneous, and parenteral routes. Human central nervous system effects by ingestion and possibly other routes general anesthesia, hallucinations or distorted perceptions, and convulsions. An eye irritant. A widely abused, controlled substance. Abuse leads to habituation or addiction. In medicine, it is used as a local narcotic anesthetic applied topically to mucous membranes. The free base is soluble... 

Ketamine typically is administered intravenonsly bnt also is effective by intramnscnlar, oral, and rectal rontes. The indnc-tion doses are 0.5 to 1.5 mg/kg IV, 4 to 6 mg/kg IM, and 8 to 10 mg/ml. Onset of action after an intravenous dose is similar to that of the other parenteral anesthetics, but the duration of anesthesia of a single dose is longer. For anesthetic maintenance, ketamine occasionally is continued as an infusion (25 to 100 (tg/kg per minute). Ketamine does not elicit pain on injection or true excitatory behavior as described for methohexital, although involuntary movements prodnced by ketamine can be mistaken for anesthetic excitement. 

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