Question

Explain the transport process of drugs administered intravenously include assumptions and limitations please

Answer 1

Absorption is the transfer of a drug from its site of administration to the bloodstream. The rate and extent of absorption depends on the route of administration, the formulation and chemical properties of the drug, and physiologic factors that can impact the site of absorption. When a drug is administered intravenously, absorption is not required because the drug is transferred from the administration device directly into the bloodstream. In the case of intravenous administration, the entire dose of the drug is available to move to the sites of drug action. Administration by other routes may result in less availability due to incomplete absorption. When this occurs, less of the drug is delivered by the bloodstream to the site of action. When a tablet or capsule is swallowed it must dissolve before it can be absorbed. The dissolving of a tablet or capsule is referred to as dissolution. Manufacturing processes and the water solubility of the drug affect dissolution rates. Highly water-soluble medications dissolve more readily in the gastrointestinal (GI) tract, while fat-soluble drugs dissolve more slowly. Drugs with smaller particle sizes go into solution more readily. The inert ingredients added to formulations can also affect their dissolution. Manufacturers must avoid producing tablets so compacted that they pass through the GI tract without ever dissolving. Tablets that dissolve too early are also problematic, because they taste bad and are difficult to swallow. Special formulations or coatings can be used to delay dissolution, thereby protecting the drug from stomach acid or allowing the gradual release of the drug to intentionally lengthen the absorption process. These are referred to as delayed or sustained release formulations. Liquid preparations do not require the step of dissolution. This explains the more rapid onset of action seen with liquid formulations as compared with the same drug given in tablet or capsule form.