Thiopental, safety

Because thiopental causes myocardial and respiratory depression and has a very narrow margin of safety, it has been largely superseded by non-barbiturates. 

Compared to thiopental, etomidate has a greater margin of safety between anaesthetic dose and the dose that produces cardiorespiratory depression. 

Sodium pentothal (also called thiopental sodium) is commonly used as an intravenous anesthetic. The onset of anesthesia and the loss of consciousness occur within seconds of its administration. Care must be taken when administering sodium pentothal because the dose for effective anesthesia is 75% of the lethal dose. Because of its toxicity, it cannot he used as the sole anesthetic. It is generally used to induce anesthesia before an inhalation anesthetic is administered. Propofol is an anesthetic that has all the properties of the perfect anesthetic It can he used as the sole anesthetic by intravenous drip, it has a rapid and pleasant induction period and a wide margin of safety, and recovery from the drug is rapid and pleasant. 

Thiopental and propofol are the two most commonly used parenteral agents. Thiopental has a long-established track record of safety. Propofol is advantageous for procedures where rapid return to a preoperative mental status is desirable. Etomidate usually is reserved for patients at risk for hypotension and/or myocardial ischemia. Ketamine is best suited for patients with asthma or for children undergoing short, painful procedures. 

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