Chapter 6 Flashcards
What is an opioid? How do they work in the body?
Opioids are a class of drugs that act on the opioid receptors in the central nervous system to relieve pain. They work by mimicking the action of endogenous opioids, binding to opioid receptors to inhibit the transmission of pain signals, leading to analgesia, euphoria, and in some cases, sedation.
What are the endogenous opioids? Under what conditions might they be released? What happens when they are released?
Endogenous opioids are natural ligands for opioid receptors in the body, including enkephalins, β-endorphins, and dynorphins. These are typically released in response to pain or stress and help modulate pain, induce euphoria, and have the potential to cause addiction when overstimulated
What are the therapeutic uses for opioid agonists, mixed agonists, and antagonists?
Opioid agonists/mixed: Used for pain relief, sedation, anxiety reduction, and as cough suppressants. They also reduce gastrointestinal tract activity
Antagonists: These are used to reverse opioid overdoses and prevent relapse in opioid addiction treatment
Under what medical conditions would an opioid agonist be prescribed instead of a non-opioid pain reliever?
Prescribed for moderate to severe pain where non-opioid analgesics, such as NSAIDs or acetaminophen, are ineffective. Conditions may include post-surgical pain, cancer-related pain, or severe dental pain
What are the pharmacokinetic properties of opioids?
Absorption: easily absorbed and cross membranes rapidly. They generally have an onset within one hour,
Dristribution: heavily bound to plasma proteins
Metabolized through Phase I metabolism, and their effects last 4-6 hours.
Excretion occurs via renal filtration
What are some of the common adverse reactions when someone takes opioids? What would increase those risks?
Respiratory depression, nausea/vomiting, constipation, pupil constriction, urinary retention, anxiety, nervousness, cardiovascular depression, biliary tract constriction
Histamine release, preg and nursing issues, allergic, drug interactions, physiological tolerance and addiction.
Risks increase with higher doses, prolonged use, or when combined with other CNS depressants like alcohol
Why is heroin so addictive?
Heroin is metabolized into morphine, crossing the blood-brain barrier rapidly, leading to intense euphoria. The fast onset of its effects, followed by quick withdrawal symptoms, contributes to its highly addictive nature
How are morphine and codeine used pharmacologically? How are they related to heroin?
Morphine is the “standard” opioid for severe pain management and is highly potent. (Schedule II drug)
Codeine is weaker and often combined with non-opioids like acetaminophen for mild to moderate pain relief, commonly used in dentistry. (Schedule V drug)
Heroin is a derivative of morphine and is highly addictive due to its rapid metabolism into morphine (Shedule I drug)
Why are opioid agonists like oxycodone and hydrocodone commonly used for dentistry?
Oxycodone and hydrocodone are commonly used in dentistry to manage moderate to severe dental pain following procedures like tooth extractions. They are often combined with non-opioid analgesics like acetaminophen for synergistic effect
What are the common drug interactions with opioid agonists?
Opioids interact with alcohol, barbiturates, and MAOIs, which can increase CNS depression. Herbal supplements like St. John’s wort may either increase sedation or decrease opioid effectiveness.
Barbiturates or rifampin in patients recieving methadone treatment for addiction- increased withdrawal symptoms
How is naloxone used therapeutically? What is the mechanism by which it works?
Naloxone, an opioid antagonist, is used to reverse opioid overdoses by rapidly displacing opioids from their receptors, particularly those responsible for respiratory depression. It can induce withdrawal symptoms in opioid-dependent individuals
How is methadone used to treat heroin addiction? What is the major pharmacokinetic difference between heroin and methadone?
Methadone is used to ease heroin withdrawal and reduce cravings due to its longer duration of action compared to heroin, which allows for less frequent dosing. Methadone also prevents the euphoric effects of heroin
What other treatments are available to treat opioid addiction?
Other treatments include buprenorphine and naloxone combinations (e.g., Suboxone®) and naltrexone, an opioid receptor antagonist used to prevent relapse and treat both opioid addiction and alcoholism
What are some legal and illegal drugs that are commonly abused?
Legal: Opioids, alcohol, tobacco, anxiolytics.
Illegal: Heroin, cocaine, methamphetamines
Which factors will affect the likelihood of a drug being abused? Why does each factor have that effect?
Factors include type of drug, time to onset, time to withdrawal, method of delivery, and ease of access.
Faster onset and shorter time to withdrawal increase addiction risk
