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Drugs 4 lecture recording on 20 January 2025 at 09.51.24 AM

Introduction

Understanding drugs and their delivery methods is critical for effective clinical practice, particularly for optimizing patient outcomes. Knowledge in this area allows healthcare professionals to select the most appropriate drug administration routes tailored to individual patient needs, enhancing efficacy and minimizing adverse effects. A bonus assignment is available for additional grades and will be posted on Brightspace.

Key Concepts of Drug Administration

First Pass Effect

The first pass effect refers to the metabolism of orally administered drugs as they are absorbed through the gastrointestinal (GI) tract and transported via the portal vein to the liver before reaching systemic circulation. This can lead to significant reduction in bioavailability (the proportion of the drug that enters circulation when introduced to the body) and, therefore, effectiveness.

  • Key Structures Involved: Major organs such as the liver, stomach, pancreas, and intestines participate in metabolic processes that govern drug pharmacokinetics.

  • Conditions in the GI Tract: Oral drugs encounter harsh environments including stomach acids and intestinal bacteria, which can further impact the drug’s stability and absorption.

Delivery Methods

Oral Administration

Oral administration is one of the most common and convenient routes but it is subject to the first pass effect, which means drugs may not reach systemic circulation in their active form.

  • Factors Affecting Absorption: The unique conditions of the GI tract (pH levels, presence of food, and gut flora) significantly influence how well drugs are absorbed and their subsequent therapeutic effects.

Parenteral Administration

Parenteral administration involves delivering drugs directly into the body bypassing the GI tract. This method is vital in scenarios where rapid relief is critical or when patients are unable to take medications orally.

  • Methods Include:

    • Injection: This allows for immediate entry into systemic circulation. While it provides advantages like faster action and controlled dosing, it also comes with risks like infection, pain at the injection site, and potential for serious consequences in cases of overdose.

Types of Parenteral Routes

  • Inhalation: This method ensures direct delivery to the lungs, offering rapid absorption due to the large surface area. Additionally, inhalation bypasses the first pass effect altogether, making it an effective method for respiratory medications.

  • Intranasal: Provides quick absorption via the nasal mucosa and can lead to rapid therapeutic effects on the central nervous system, making it useful for certain medications like naloxone.

  • Topical Application: Drugs applied to the skin can be designated for local effects or formulated for systemic effects through transdermal patches, which enable continuous release of medication over time.

  • Intravenous (IV): This route involves direct injection into the vascular system, ensuring rapid action and precise control over drug levels. IV administration is common in hospitals for urgent treatment protocols and maintenance of therapeutic levels.

  • Subcutaneous/Intramuscular: These methods facilitate sustained drug release but often necessitate proper technique and may cause discomfort.

Specific Injection Techniques

  • Intradermal: Leveraged for small doses, typically for tests such as allergy assessments.

  • Subcutaneous: Commonly used for insulin administration; the absorption is slower and often less painful than other methods.

  • Intramuscular: Allows for faster absorption because of the high vascularity in muscle tissues; often used for vaccines and other therapies requiring deeper delivery.

  • Intravenous: The fastest route for administering medications directly into circulation, crucial for emergency situations.

  • Intraosseous: Employed in emergencies to gain rapid access to the circulatory system through the bone marrow when IV access is challenging.

  • Intrathecal: This involves delivering medications directly to the cerebrospinal fluid, often requiring advanced technical skills due to the high-risk nature of the procedure.

Considerations for Drug Administration

When selecting a drug administration method, healthcare professionals must consider several factors including:

  • Pros and Cons: Every delivery method has inherent advantages and disadvantages. The specific clinical situation often dictates the most appropriate route.

  • Monitoring Needs: Especially critical for parenteral routes, due to complications that may arise from incorrect dosing or administration errors.

  • Aseptic Techniques: Special skills and techniques for handling and administering drugs are vital to prevent infections and ensure optimal delivery of the therapeutic agent.

Conclusion

A comprehensive understanding of various drug delivery methods, their mechanisms, and implications for pharmacotherapy is crucial for enhancing patient care and ensuring efficacy in treatment protocols. Students are advised to frequently check Brightspace for assignment updates and are encouraged to discuss any questions regarding drug delivery mechanisms during upcoming classes.