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→Drugs in this Group
==Drugs in this Group==
==Drugs in this Group==
===Thiopental===
===Thiopental===
Thiopental (also ''Thiopentone'') causes a rapid loss of conciousness with time of onset being influenced by premedication agents. It is considered a '''ultra short acting''' barbituate, with effects seen within 15-30s following injection, and has a rapid recovery period, commonly 10-15 minutes. The duration and depth of anaesthetic, however, depends upon the ''amount'' of drug injected, ''speed'' of injection, and ''rate of distribution'' in non-fatty and fatty tissues.
Thiopental (also ''Thiopentone'') causes a rapid loss of conciousness with time of onset being influenced by premedication agents. It is considered a '''ultra short acting''' barbituate, with effects seen within 15-30s following injection, and has a rapid recovery period, commonly 10-15 minutes. The duration and depth of anaesthetic, however, depends upon the ''amount'' of drug injected, ''speed'' of injection, and ''rate of distribution'' in non-fatty and fatty tissues. Recovery is dependent on redistribution of thiopental from plasma to adipose tissue so animals with minimal fat will take longer to recover.
Thiopental is available as a yellowish powder, which once reconsituted and stored correctly, can be used for up to 3-4 days. It comes as 2.5%, 5% and 10% solutions.
Thiopental is available as a yellowish powder, which once reconsituted and stored correctly, can be used for up to 3-4 days. It comes as 2.5%, 5% and 10% solutions.
Thiopental is highly protein-bound and so the dose should be reduced, or thiopental avoided in animals with hypoproteinaemia.
Thiopental is highly protein-bound and so the dose should be reduced, or thiopental avoided in animals with hypoproteinaemia.
Care should also be taken in sighthounds as they do not possess the enzyme to cleave the sulphur molecule from the thiopental, which is the first stage of metabolism of the drug, and so recovery may be prolonged in these patients.
Care should also be taken in sighthounds as they take longer to recover this may be because they have minimal fat or because they metabolise it differently.
===Pentobarbital===
===Pentobarbital===
Pentobarbital is an oxybarbiturate which is no longer available at anaesthetic doses, but used as an euthansia agent. It causes a rapid onset of anaesthesia (40-120s) but has a longer duration of action compared with thiopental (1-2 hours). Recovery is dependent on hepatic metabolism. Its main indication of use is for the treatment of intractable seizures, long term sedation in ICU and euthansia.
Pentobarbital is an oxybarbiturate which is no longer available at anaesthetic doses, but used as an euthansia agent. It causes a rapid onset of anaesthesia (40-120s) but has a longer duration of action compared with thiopental (1-2 hours). Recovery is dependent on hepatic metabolism. Its main indication of use is for the treatment of intractable seizures, long term sedation in ICU and euthansia.