S-Ketamine is a water soluble molecule that structurally resembles phencyclidine. The commercial preparation of S-Ketamine is a racemic mixture of two optical enantiomers R(-) and S(+), and a preservative benzethonium chloride.
The presence of asymmetric carbon atom results in the existence of two optical isomers of ketamine.
The racemic form of ketamine has been the most frequently used preparation. S(+)-ketamine is also becoming available, has a potency of two times more than racemic mixture. S(+)ketamine produces more intense analgesia, faster recovery, and less salivation; however, the incidences of side effects such as amnesia, hallucinations, altered cognitive performance, nightmares, nausea and vomiting,’ and cardiovascular effects are equal with racemic mixtures.
The fact that individual optical isomers of S-Ketamine differ in their pharmacologic properties suggests that this drug interacts with specific receptors.