Pharmacology and Herbal Therapies Overview

Week 3 Takeaways

Drug Processes and Absorption

  • Drug Phases

    • Pharmacokinetics: Focuses on drug movement through the body, emphasizing what the body does to the drug.

    • Pharmacodynamics: Examines what the drug does to the body as it moves through, demonstrating that both pharmacokinetics and pharmacodynamics are necessary components of drug action.

Pharmacokinetics

  • Oral Drug Movement into the Bloodstream:

    • Route: by mouth → gastrointestinal (GI) tract → mucosal lining of the small intestine (SI) → absorption ends in SI.

    • Note: Non-oral medications (like inhaled, injections, and intravenous (IV)) do not pass through the GI tract.

    • Routes of Administration:

    • Inhaled medications: via respiratory tract.

    • Injections: directly into the muscle or subcutaneous (fat) tissue.

    • IV medications: directly into the bloodstream.

  • Disintegration:

    • Definition: The breakdown of oral drugs into smaller, absorbable particles.

    • Note: Some formulations allow for 100% of the tablet/capsule to consist of active drug.

  • Dissolution:

    • Definition: The process of combining small drug particles with liquid to form a solution.

    • Impact: More rapidly absorbed since disintegration is not required.

  • Enteric-coated Drugs (EC):

    • Function: Designed to resist gastric acid in the stomach and do not break down until reaching the small intestine (SI).

Factors Affecting Absorption

  • Pain and stress can slow GI emptying, which results in prolonged retention in the stomach.

Routes of Administration

  • Intramuscular (IM) Drugs: Faster absorption due to increased blood flow in muscles.

  • Subcutaneous (SubQ) Drugs: Absorption is slower due to decreased blood flow in fat tissues; influenced by body fat percentage.

  • Comparative Speed of Administration:

    • Oral (PO) drugs are slower than IM and SubQ.

    • IV drugs are the most rapid, taking seconds to minutes.

Drug Distribution

  • Definition: Movement of drugs from circulation to body tissues.

  • Mechanism: Distribution is facilitated by protein binding.

  • Toxicity Risk: If drugs cannot bind effectively, they may remain as “free floating” in circulation, leading to potential toxicity.

  • Blood-brain Barrier: A natural protective mechanism preventing foreign substances from entering the brain.

    • Note: It can also inhibit beneficial substances, necessitating advanced methods to bypass it.

Digestion Processes

  • Drug Metabolism: The body’s chemistry changes the drug into a form suitable for excretion, primarily occurring in the liver, utilizing enzymes to convert drugs into metabolites.

    • Implication: Slowed metabolism can cause accumulation, potentially leading to toxicity.

  • Half-Life:

    • Definition: The time it takes for the amount of drug in the body to be reduced by half.

    • Significance: Liver or kidney dysfunction results in a prolonged half-life, leading to drug accumulation and possible toxicity.

  • Steady State: Achievement of a plateau level, indicating how long it takes to reach a therapeutic drug concentration.

  • Loading Dose: A large initial dose used while waiting for a steady effect to be reached.

Drug Elimination

  • Primary route: Kidneys.

  • Conditions Affecting Elimination:

    • Prerenal Conditions: Issues such as lack of blood flow, dehydration.

    • Intrarenal Conditions: Lack of filtering and balance.

    • Postrenal Conditions: Accumulation due to obstruction.

Pharmacodynamics

Primary and Secondary Effects

  • Primary Effect: The desirable response, where the drug effectively treats the symptoms it is designed to address.

  • Secondary Effect: Can be desirable or undesirable; refers to new symptoms that become treated inadvertently.

  • Drug Response Relationship: The body’s physiological response corresponds to changes in drug concentration levels.

Bodily Responses Related to Drug Dynamics

  • Potency: The amount of drug necessary to produce a specific physiological response.

  • Maximal Effect: The point at which increasing the dosage does not increase the effect any further.

  • Therapeutic Index: The ratio between the therapeutic dose and the toxic dose, with some drugs exhibiting large therapeutic windows while others have narrow differences.

  • Onset: The time taken for the drug to reach the minimum effective concentration.

  • Peak: The highest concentration of the drug in the bloodstream, noting that some drugs do not exhibit a clear peak.

  • Duration: The total length of time the drug maintains a therapeutic effect.

Lab Works and Receptor Interactions

  • Too Low: Indicates infection is not adequately treated; dose must be increased.

  • Therapeutic Level: Infection effectively treated; continue dose.

  • Too High: Risk for damage; dosage must be reduced or held.

Receptor Theory

  • Definition: Drugs act by binding to receptors, sometimes of a specific nature, with the following interactions:

    • When activated, drugs produce a desired response.

    • When inactive, drugs block a response.

  • Agonists: Substances that activate receptors, leading to a desired physiological response.

  • Antagonists: Substances that prevent receptor activation, effectively blocking responses.

  • Nonspecific Drug Effects: Some drugs (like beta-1 and beta-2 agonists) can affect multiple receptor sites, thus exerting effects across various body systems.

Mechanisms of Drug Action

  • Stimulation: Increases the physiological activity or effect.

  • Depression: Reduces physiological activity or effect.

  • Irritation: Stimulates the body to excrete the substance.

  • Replacement: Replenishing normal hormones in the body.

CNS Depressants and Vital Signs

  • Common effects include decreased values in respiratory rate, heart rate, and blood pressure.

  • Important Note: Do not administer more than one CNS depressant simultaneously.

    • Relevant Medications: Pain medications, anti-anxiety medications, anti-seizure medications, sleep medications, alcohol, and herbal remedies.

Affects and Reactions

Drug Effects

  • Side Effects: Generally less severe; all drugs are known to have side effects, and patient education is vital regarding these.

  • Adverse Reactions: Can range from mild to severe; these are unintended and unexpected, often resulting in undesirable effects.

  • Tolerance: This indicates a decrease in responsiveness to the drug over the course of therapy, necessitating dose adjustments.

Types of Drug Interactions

  • Additive Drug Effects: ($1 + 1 = 2$) The sum of effects produced by two drugs when taken together is equal to the sum of their individual effects.

  • Synergistic Drug Effects: ($1 + 1 = 3$) The effect of two drugs together is greater than the sum of their separate effects.

  • Antagonistic Drug Effects: ($1 - 1 = 0$) One drug reduces the effect of another drug taken simultaneously.

Week 4 Key Takeaways

Herbal and Alternative Therapies

  • General Information:

    • Complementary and alternative therapies include botanicals, nutritional products, and herbal supplements, with both positive and negative effects.

    • Important to recognize these can interact with both prescription and over-the-counter (OTC) drugs.

    • Herbal medicines are not approved for use as drugs and are unregulated by the FDA.

    • Natural products predominantly derived from plant materials include herbal medicines, dietary supplements, vitamins, minerals, oils, and probiotics.

Examples of Herbal Products and Their Uses

  • Aloe Vera:

    • Topical Applications: For skin disorders like burns and acne, also accelerates wound healing.

    • GI Disorders: Used as an oral liquid for ulcers, Crohn's disease, UC, and heartburn.

    • Other Uses: Lowers cholesterol and blood sugar, provides support for diabetes.

    • Side Effects: Known for laxative effects.

    • Interactions: Should be monitored with laxatives and diabetic medications due to overlapping effects.

  • Chamomile:

    • Effects: Calming properties for anxiety, promotes sleep, reduces stress.

    • GI Benefits: Soothes gastrointestinal complaints, relaxes muscles.

    • Side Effects: Nausea, upset stomach, and various allergic reactions related to the ragweed and daisy family.

    • Interactions: Caution with other CNS depressants because of its calming effect.

  • Echinacea:

    • Benefits: Stimulates the immune system; used for colds, flu, and infections; may suppress cancer cell growth and trigger cancer cell death.

    • Side Effects: Mild gastrointestinal (GI) upsets, potential for allergic reactions; particularly concerning for those with ragweed allergies.

    • Interactions: Caution with anti-rejection medications and autoimmune disease treatments; may interfere with antiretroviral treatments for HIV/AIDS.

  • Feverfew:

    • Properties: Anti-inflammatory and pain relief for conditions such as arthritis (moderate to mild), fever reducer, and effective for migraines and headaches.

    • Interactions: Should not be taken with warfarin and other anticoagulants due to bleeding risks; also avoid with aspirin and ibuprofen, especially 7-10 days prior to surgery.

  • Garlic:

    • Health Benefits: Lower cholesterol and blood pressure; reduces the risk of heart disease.

    • Side Effects: Heartburn, upset stomach, distinct body odor.

    • Interactions: Risk of increased bleeding with blood thinners.

  • Ginger:

    • Uses: Antinausea properties especially useful for pregnancy, motion sickness, and general nausea.

    • Benefits: Provides relief from pain, swelling, and stiffness.

    • Side Effects: Mild gastrointestinal issues, with a caution regarding uterine contractions, posing a risk for miscarriage.

    • Interactions: Risk of bleeding when taken with anticoagulants.

  • Ginkgo Biloba:

    • Effects: Reduce inflammation, provide mild pain relief; beneficial for heart, brain, and eye health, also associated with improved memory.

    • Side Effects: Mild reactions with a potential for allergic responses.

    • Interactions: Increased bleeding risk, particularly with anticoagulants and mental health medications.

  • Licorice Root:

    • Uses: For skin conditions and acid reflux (indigestion).

    • Effects on Oral Health: Known uses for oral health.

    • Side Effects: Sodium/water retention leading to hypertension or heart failure risks.

    • Interactions: Possible adverse effects when taken with blood pressure medications, diuretics, and corticosteroids.

  • Kava:

    • Properties: Used as an alcohol alternative for relaxation; effective in reducing anxiety and assisting with sleep.

    • Side Effects: Can lead to liver toxicity or failure.

    • Interactions: Should not be taken with alcohol and other CNS depressants.

  • Saw Palmetto:

    • Applications: Targets urinary symptoms associated with prostatic hypertrophy; reduces pressure in the male urethra's inner-muscle lining.

    • Interactions: Increased bleeding risk with anticoagulants.

  • St John’s Wort:

    • Uses: Effective for mild to moderate depression and anxiety; impacts serotonin levels and alleviates menopausal symptoms.

    • Side Effects: Anxiety, dry mouth, dizziness, headache, increased sunlight sensitivity.

    • Interactions: Numerous, including antidepressants, oral birth control, seizure medications, and other CNS depressants leading to amplified effects.

  • Valerian:

    • Use: Sedative properties for relief from stress, anxiety, and insomnia.

    • Side Effects: Includes dizziness, drowsiness, and vivid dreams.

    • Interactions: Other CNS depressants must be used cautiously; should be discontinued two weeks before surgical procedures to avoid anesthetic interactions.