Ever wondered why some drugs are not given orally even though swallowing a tablet is easier?
When a drug is taken by mouth, it first travels to the liver through the portal circulation before reaching systemic circulation. This process is called First-Pass Metabolism — where a significant portion of the drug gets metabolized before it can exert its therapeutic effect.
Why does it matter?
• Reduces drug bioavailability
• Alters required dose strength
• Influences route of administration
• Can lead to variability in patient response
Clinical Insight:
Drugs with extensive first-pass metabolism (like nitroglycerin or propranolol) are often given via sublingual, transdermal, or intravenous routes to bypass the liver initially.
Understanding first-pass metabolism helps pharmacists and healthcare professionals design safer and more effective drug therapies.
MBH/AB
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Definitely agreed! These aspects play a major role in dosage formulations. It is important to assess weather the drug works better in the form of a tablet/syrup/capsule or is better to be administered parenterally. The drug potency, half life and therapeutic action are also greatly affected by route of administration and type of dosage form.
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Absolutely! It is important to assess whether drugs given in different dosage forms work safely and show effective therapeutic action. Different formulations work differently in our body and these aspects need to be considered for the choosing the right route of administration of drug.
Ture, it’s an important factor to consider during drug formulation, as it directly affects drug’s effectiveness, action, and patient response. Due to first pass metabolism, many drugs show reduced BA, which can limit their activity. Understanding this helps in designing safer and more effective drug therapies, including alternative formulations like iv, im routes to bypass this effect.