Pharmacology DosingPharmacology DosingThis model is a study of the absorption of drugs into the body. For medical purposes, it is important to have a constant concentration of drugs in order to have the desired effect while minimizing side effects. However, drugs are usually given in capsules of a certain dosage rather than a steady stream. Moreover, drugs taken orally must first be absorbed by the bloodstream before they can take effect.
This model simulates a drug given in dosages of 750 units every 6 hours. Column A gives the time (in hours). Column B gives the dosage given for any given instant. Column C gives the quantity of the drug currently in the digestive system (i.e. within the body but not yet active). Column D gives the quantity of the drug currently absorbed within the bloodstream, and Column F gives the concentration of the drug in the bloodstream. Columns H through L contain the settings for the model, which can be manipulated to produce desired effects. Finally, the plasma concentration over time is displayed on a graph.
All of the settings can be changed in Columns H through L. Changing the body volume determines how much of a drug is needed to achieve a given concentration. The Dosage per Day and Doses Per Day options determine how much of the drug is given and how often. These options in turn determine several of the other options, including interval and dose.
The absorption and excretion options affect the transference of the drug between the intestines and the bloodstream. A higher absorption rate means that the drug is more quickly moved from the intestines and the bloodstream. The excretion rate determines how quickly the drug leaves the body once in the bloodstream.
Whenever a new dose is applied, the plasma concentration will rapidly increase as the drug is absorbed, then decrease as the absorbed drug is excreted. After a number of iterations, the average concentration of the drug should begin to stabilize.