What is the pH of thiopental?
During induction of anesthesia, this phenomenon may be encountered when a basic drug such as thiopental (pH 8.5-10.5) remains in the intravenous (IV) tubing at the time of injection of acidic drugs such as some of the muscle relaxants.
Does thiopental increase ICP?
High dose thiopental can be used to reduce refractory raised intracranial pressure in patients with severe head injury who are unresponsive to primary and secondary management measures as detailed in BSUH Guidelines for the Management of Traumatic Brain Injury.
Why is thiopentone contraindicated in porphyria?
absence of suitable veins for IV administration. hypersensitivity to barbiturates. acute intermittent porphyria Δ (barbiturates enhance porphyrin synthesis, and therefore are absolutely contraindicated in patients with a history of acute intermittent porphyria)
Why is thiopental fast acting?
The high lipid solubility of thiopental (in contrast to pentobarbital) may well be responsible for the rapid equilibration with brain, and thus for the ultrashort duration of action.
Is thiopental an acid or base?
Red arrows indicate the pH at which lidocaine (a weak base) and thiopental (a weak acid) are prepared in solution. At body pH, much of the drug becomes unionized and can cross membranes.
What is the pH of propofol?
The pKa is 11. The octanol/water partition coefficient for propofol is 6761:1 at a pH of 6 to 8.5.
How does thiopental reduce ICP?
Nevertheless, among the different protocols used to lower ICP, propofol and thiopental sodium are known as the drugs with strong vasoconstriction effect on cerebral vessels and the ability to reduce cerebral blood volume (CBV), cerebral blood flow (CBF) and ICP.
Why barbiturates are contraindicated in porphyria?
ALA synthetase is involved in the porphyrin production pathway, and therefore barbiturates are contraindicated in patients with acute intermittent porphyria (AIP) or variegate porphyria because they may precipitate an attack, manifested by severe abdominal pain, nausea, vomiting, psychiatric disorders, and neurologic …
Is thiopental water soluble?
The free acid (thiopental) melts at 158–160˚C. At 20˚C, thiopental sodium is soluble in 1.5 parts of water. It is partially soluble in alcohol and is practically insoluble in ether, benzene, and petroleum ether.