Question

Court-ordered medications have just been granted for your patient. Historically he has done well on chlorpromazine. You would like to order an oral dose with an equivalent IM dose if the oral dose is refused. Which pharmacokinetic parameter affects this conversion?

Bioavailability

Elimination

Anticholinergic side effects

Frequency of the patient’s behavioral emergencies

Answer 1

Chlorpromazine is a phenothiazine antipsychotic medication and is used to treat people with mental or psychotic disorders like schizophrenia. There are variety of receptors inside our brain and chlorpromazine blocks certain receptors most profoundly dopamine 2. In this way, it helps in pausing certain neuro signal from transmitting and controlling and improving the behavior of individual.

Fully removal of drug from the body is called elimination and to fully eliminate chlorpromazine it can even take 3-18 days. Chlorpromazine can also cause anticholinergic side effects and does not usually make a big impact on the conversion.

Bioavailability is a big factor that affects this conversion. The tendency of our body to absorb drug is called the bioavailability of drug. Now, when compared to IM (intermuscular) dose, the bioavailability of oral chlorpromazine is only 30%. This big difference in bioavailability will not help the patient to block sufficient receptor in brain and will definitely affect the result of drug.