Pharmacology: Opioids Lecture Notes

A set of vocabulary flashcards covering key opioid pharmacology concepts, drug classifications, mechanisms of action, adverse effects, dosing protocols, and nursing care.

Morphine

A natural opioid prototype extracted from the dried juice of the poppy seedpod (opium) that acts primarily at mu receptors to relieve moderate to severe pain.

Papaverine

A non-analgesic, smooth muscle relaxant compound naturally contained within opium alongside morphine and codeine.

First-Pass Hepatic Inactivation (Morphine)

The extensive inactivation of oral morphine during initial liver transit, necessitating substantially larger oral doses compared to parenteral doses to achieve equivalent analgesia.

Respiratory Status Threshold for Opioids

The clinical assessment cutoff where an opioid dose must be withheld and the prescriber notified if a patient's respiratory rate is less than $12\,\text{breaths per minute}$.

Incentive Spirometer

A post-operative breathing assistance device used in ICOUGH practices to help perform deep breathing exercises ($10\,\text{times per hour}$ while awake) to keep lungs healthy and clear secretions.

Histamine Release (Morphine)

A non-immunologic drug effect of morphine causing peripheral vasodilation, orthostatic hypotension, and pruritus.

Orthostatic Blood Pressure Measurement Procedure

An assessment protocol where blood pressure and pulse are measured after the patient lies down for $5\,\text{minutes}$, then re-measured $1\,\text{minute}$ and $3\,\text{minutes}$ after standing; a drop in systolic BP $\ge 20\,\text{mmHg}$ or diastolic BP $\ge 10\,\text{mmHg}$ is abnormal.

Miosis

Pupillary constriction caused by opioids acting on the autonomic nervous system, which can reduce vision in dim light and progress to pinpoint pupils in toxic doses.

Opioid Dysphoria

An uncommon reaction characterized by a sense of anxiety and unease that may occur when morphine or other opioids are administered in the absence of pain.

Opioid-Induced Neurotoxicity

A neurologic complication manifesting as delirium, agitation, myoclonus, and hyperalgesia, primarily triggered by renal impairment, preexisting cognitive deficits, or prolonged high-dose opioid therapy.

Chemoreceptor Trigger Zone (CTZ)

An area in the medulla directly stimulated by opioids like morphine, inducing emesis and nausea particularly during initial dosing or in ambulatory patients.

Opioid-Induced Constipation (OIC) Regimen

A preventive bowel strategy initiated on day 1 of opioid therapy utilizing a stimulant laxative (senna or bisacodyl) plus an osmotic laxative (polyethylene glycol / MiraLax), while avoiding bulk-forming fiber like psyllium.

Opioid Withdrawal Timeline

A course of symptoms following the last dose where physical symptoms peak at $72\,\text{hours}$ (chills, fever, diarrhea, dilated pupils), begin to lessen by $1\,\text{week}$, transition to psychological symptoms by $2\,\text{weeks}$, and linger as cravings or depression at $1\,\text{month}$.

Classic Opioid Toxicity Triad

The hallmark clinical presentation of acute opioid overdose consisting of coma, severe respiratory depression (as low as $2\text{--}4\,\text{breaths per minute}$), and pinpoint pupils.

Fentanyl

A strong Schedule II synthetic opioid agonist with a potency approximately $100\times$ that of morphine, accounting for over $60\%$ of national overdose fatalities.

CYP3A4 Inhibitors with Fentanyl

Medications such as ritonavir and ketoconazole that inhibit fentanyl metabolism, leading to elevated fentanyl blood levels and increased risk of toxicity.

Opioid Equianalgesic Chart

A standardized dosing guide establishing relative potency among opioids in morphine equivalents (e.g., $0.1\,\text{mg}$ IV fentanyl = $1.5\,\text{mg}$ IV hydromorphone = $10\,\text{mg}$ IV morphine).

Hydromorphone (Dilaudid)

A strong synthetic opioid agonist with minimal histamine release compared to morphine, indicated for severe pain ($7\text{--}10$) and administered IV over at least $2\text{--}3\,\text{minutes}$.

CYP2D6 Metabolism (Codeine)

The hepatic enzyme pathway responsible for converting approximately $10\%$ of codeine into its active form, morphine; absent in non-converters and highly active in ultrarapid metabolizers.

Codeine FDA Age Recommendation

An FDA safety advisory recommending against the use of codeine-containing medications in children under $18\,\text{years of age}$ due to unpredictable metabolism and fatal risk in ultrarapid metabolizers.

Norco (Hydrocodone / Acetaminophen)

A Schedule II combination pain medication combining hydrocodone with acetaminophen, presenting a critical safety risk for severe hepatotoxicity if maximum daily acetaminophen limits are exceeded.

OxyContin Reformulation (2010)

An abuse-deterrent redesign of extended-release oxycodone tablets that forms a thick viscous gel when exposed to water or alcohol, preventing crushing and syringe injection.

Tramadol (Ultram)

A Schedule IV centrally acting synthetic opioid that acts as a weak mu-receptor agonist and inhibits norepinephrine and serotonin reuptake, posing risks of serotonin syndrome and seizures.

Patient-Controlled Analgesia (PCA) Pump

A specialized infusion system allowing patients to self-administer IV opioids on demand within pre-programmed safety limits; governed strictly by the rule that only the patient may press the button.