I.v. anesthetics are relatively hydrophobic and lipophilic compounds

Barbiturates also inhibit the neuronal N-type acetylcholine receptor

IMMEDIATELY AFTER I.V. INJECTION, they distribute rapidly to the well-perfused tissues,
including the brain → general anesthesia occurs rapidly (within ~ 1 min)

LATER, they redistribute to the less well-perfused tissues, such as the muscle, skin and adipose tissue.
These have large mass → remove the anesthetic from the brain → the patient wakes up in a few minutes

The anesthetic action of i.v. anesthetics is terminated by redistribution, not by elimination.
The rate of redistribution is quite similar for all i.v. anesthetics;
therefore, after a single anesthetic dose, their duration of action is also similar (i.e., 5-10 min).

decreased tissue perfusion (e.g., in cardiac failure and septic shock)

In such conditions, the dose of i.v. anesthetic should be lowered lest the anesthesia should be too long

induction of anesthesia before inhalation anesthesia, if the inhal. anesthetic slowly induces anesthesia
(e.g., halothane), or has unpleasant odor or airway irritating property (e.g., isoflurane, desflurane)

short anesthesia for short surgery or painful intervention (e.g., reposition of a dislocated joint)

continuous infusion to produce long-lasting anesthesia.
After discontinuation of the infusion, the patient wakes up in 10 minutes even if propofol was infused
for 3 hours. Propofol is the preferred i.v. anesthetic for TIVA (total intravenous anesthesia). At a lower
dose rate, propofol is also used for continuous sedation of patients in ICUs

Hydroxylation on the aliphatic chains linked to C5 of the barb. ring

Decrease the cerebral blood flow which decreases the incracranial pressure -> decrease of ocular pressure

exert anticonvulsive effect → thiopental is valuable in the treatment of status epilepticus

injectible solution is basic, can precipitate as free acid in a acidic solution

If the i.v. injected thiopental conc. is >2.5%, it may induce pain and thrombophlebitis

In asthmatics, they may induce histamine release and wheezing

Cause accumulation of porphyrins in patients deficient in some
downstream enzymes of the heme synthetic pathway.

By glucuronidation (mainly) and sulfation at the hydroxyl group

used by orthopedic surgeons in SCOLIOSIS CORRECTION SURGERY

Decreases blood pressure because of vasodilatation and negative inotropic effect

Toxic effect on mitrochondria, mainly in skeletal and cardiac muscle

Diffuses into Mit., dissociates its phenolic proton, thus dissipating the inwardly directed H+ gradiant that drives ATP synthase.

Cardiac failure: acute refractory bradycardia (may lead to asystole), hypotension, and ST elevation

Rhabdomyolysis → ↑serum K+, ↑serum CK, myoglobinuria → renal failure

Hepatomegaly with fatty liver (probably caused by inhibition of fatty acid oxidation)

appears to have proconvulsive effect (contraindicated in seizures)

↓ cerebral metabolic rate, O2 consumption → ↓ cerebral blood flow, intracranial and intraocular pressure

→ the CARDIOVASCULAR FUNCTION IS STABLE during etomidate anesthesia → etomidate is usually reserved for patients at risk for hypotension and/or myocardial ischemia

used by ambulance services for sedation and pain suppression in patients

This occurs seldom in children → ketamine is a preferred anesthetic in pediatric surgery