Calculating the equivalent dose for intraperitoneal injection

[Eagle9]

Hello guys

Imagine that we have got a rat and we administer a certain dose (let it be 4.0 µl of a 0.052 M solution) of some (let’s say Propionic Acid - PPA) drug in a intracerebroventricular way – directly in rat’s brain. Now imagine that we administer the same drug in intraperitoneal way – directly in body cavity. In order to achieve same physiological impact on brain the dose in second approach should be different – higher (since in the second method the PPA needs to cover more distance in order to achieve brain), but how much higher? How this can be calculated?

 

[Fervent Freyja]

Intracerebroventricular administration of drugs are very uncommon to begin with and most drugs don't have formulations for that method already established. So, converting them to use for intraperitoneal route would be pointless, the formulas for most drugs that can be injected in that manner will already be published by the pharmaceutical industry. You should be able to find what you already need. Also, some drugs are injected into the brain in the first place because of difficulties crossing the blood-brain barrier, massive doses of some drugs may not be effective regardless. If you want to know about a specific drug that is commonly used in animal testing via the intracerebroventricular route, then you could possibly find some methods of calculating the equivalent dosage via the intraperitoneal route, if it is already a common practice of doing so. Really, the specific drug needs to be known to fully answer your question.

http://www.ncbi.nlm.nih.gov/pubmed/19558257