Originally Posted by fmichael

Dear Gabbycakes -

My apologies for the delay in getting back to you, however, I haven't been able to find much. Ketamine is, as you are aware is formulated as "a slightly acid (pH 3.5-5.5)." See, Prescribing Information for KetalarŪ (Ketamine Hydrochloride Injection, USP), in pdf format: http://www.jhppharma.com/products/PI...ar-Full-PI.pdf

In fact, there is one recent report in which it has been used in combination with propofol to lower the pH of strait 1% propofol injection from 7.86 to 5.84 when administered as a 1% propofol-ketamine, thereby reducing the painfulness of the injection itself. Preventing pain on injection of propofol: a comparison between peripheral ketamine pre-treatment and ketamine added to propofol. Hwang J, Park HP, Lim YJ, Do SH, Lee SC, Jeon YT, Anaesth. Intensive Care 2009 Jul; 37(4): 584-7:

Abstract
The purpose of this study was to examine possible peripheral mechanisms for the reduction of propofol injection pain by the addition of ketamine. We hypothesised that pH changes associated with the addition of ketamine to propofol decrease propofol-induced pain on injection. We compared the efficacy of intravenous ketamine pretreatment under tourniquet with ketamine added to the propofol. In the pre-treatment group, patients received ketamine 10 mg in a total volume of 1.0 ml with 0.9% saline (n = 94; Group P) under tourniquet for 30 seconds before administration of propofol after release of the tourniquet. In the mixture group, propofol 9 ml was mixed with ketamine 10 mg in 0.9% NaCl 1.0 ml (n = 94, Group M). Pain was assessed with a four-point scale: 0 = no pain, 1 = mild pain, 2 = moderate pain, 3 = severe pain at the time of propofol injection. The pH of propofol, ketamine and a range of propofol-ketamine mixtures were also measured. Forty-eight patients (51%) in Group P complained of pain on injection compared with 28 patients (30%) in Group M (P = 0.005). The pH of the 1% propofol-ketamine mixture was 5.84 while 1% propofol had a pH of 7.86. Our results support pH changes as a more important cause for the decrease in propofol injection pain with the addition of ketamine to propofol than a peripheral effect of ketamine.

PMID: 19681415 [PubMed - indexed for MEDLINE]

http://www.ncbi.nlm.nih.gov/pubmed/1...ubmed_RVDocSum

That said, how quickly the body responds to changes in pH and the mechanisms by which it does so are matters well beyond my understanding: something one would have to know before establishing a link between the infusion of ketamine and tooth damage. Sorry I can't be more helpful.

Mike