Assess with explanation the bioavailability by oral route of the following drugs with the specified properties.
Also suggest ways to achieve the therapeutic concentration if the bioavailability is not favorable.
(Note: change of route of administration should be considered as the last option of resolution)
i. Drug A will be hydrolyzed to 30% of its therapeutic dose in an acidic medium within an hour.
ii. Drug B has a hepatic extraction ratio of 50%.
iii. Drug C is a biopharmaceutical of protein nature.
i i think acidic medium =stomach, so drug interaction can be applied in this case?using some drug to alter the motility rate of gastric emptying?
ii I think the drug is OK because extraction ratio is not too high,but I have no idea to explain in detail
iii it must change the rote of administration because the drug will be digested by gastric acid.
can anyone give me an advice if my answer is valid?
Thank you very much
Your understanding of the three scenarios is partially correct. Let me provide you with a more detailed explanation and suggest ways to achieve therapeutic concentrations for each drug if the bioavailability is not favorable.
i. Drug A being hydrolyzed to only 30% of its therapeutic dose in an acidic medium (such as the stomach) within an hour means that its bioavailability by oral route is low. In this case, drug interactions or modifications that can alter the motility rate of gastric emptying could be considered to improve bioavailability. For example, co-administering an antacid or a proton pump inhibitor can decrease stomach acidity and delay drug degradation, allowing more time for absorption in the intestines. Additionally, formulation techniques such as enteric coating or sustained-release formulations can be used to protect the drug from rapid degradation.
ii. Drug B with a hepatic extraction ratio of 50% indicates that 50% of the drug is eliminated by the liver during the first pass effect. Since it is not extremely high, the drug may still have an acceptable bioavailability. However, if achieving therapeutic concentrations becomes a challenge, strategies to enhance bioavailability include increasing the dose of the drug to compensate for the portion lost during the first pass effect, utilizing prodrugs that can bypass hepatic metabolism, or using drug delivery systems that can improve liver targeting (e.g., nanoparticles or liposomes).
iii. Drug C, being a biopharmaceutical of protein nature, poses challenges for oral administration due to the potential degradation by gastric acid and digestive enzymes. In this case, changing the route of administration, such as administering the drug through injections or transdermal patches, may indeed be the most effective solution to achieve therapeutic concentrations.
Overall, your understanding of the situations is valid, but considering these additional explanations and suggestions can help in addressing the bioavailability issues for each drug.