Narcotics, Narcotic Antagonists, and Antimigraine Agents

Generic and Brand Names

Narcotics

• Narcotic Agonists
• codeine
• fentanyl (Actiq, Duragesic)
• hydrocodone (Hycodan)
• levorphanol (Levo-Dromoran)
• meperidine (Demerol)
• methadone (Dolophine)
• morphine (Roxanol, Astramorph)
• opium (Paragoric)
• oxycodone (OxyContin, Oxecta)
• oxymorphone (Numorphan)
• tramadol (Ultram)
• Narcotic Agonists-Antagonists
• buprenorphine (Buprenex)
• butorphanol (Stadol)
• nalbuphine (Nubain)
• pentazocine (Talwin)
• Narcotic Antagonists
• Naloxone (Narcan)
• Naltrexone (ReVia)

Antimigraine Agents

• Ergot Derivatives
• dihydroergotamine (Migranal)
• ergotamine (Ergomar)
• Triptans
• almotriptan (Axert)
• eletriptan (Relpax)
• frovatriptan (Frova)
• naratriptan (Amerge)
• rizatriptan (Maxalt)
• sumatriptan (Imitrex)
• zolmitriptan (Zomig)

Condition Spotlight: Pain

Pain is largely subjective, and people respond to it differently based on culture, learned experience, and environment. Two sensory nerves, the A-delta and C-fibers, generate the impulses that produce pain sensation.

Acute pain comes from tissue injury and drives the patient to seek care. Chronic pain is constant or intermittent and keeps occurring long past the point the tissue should have healed, and it interferes with daily living. Pain is also classified by source: nociceptive pain from direct pain-receptor stimulus, neuropathic pain from nerve injury, and psychogenic pain tied to emotional, psychological, or behavioral stimuli.

How Narcotic Drugs Work

Narcotic drugs react with opioid receptors, the sites that respond to the body's own peptides, enkephalins, and endorphins. Those receptors sit in the CNS, peripheral nerves, and GI tract cells, and in the spinal cord they integrate pain information. Which receptor a drug hits determines both the relief and the side effects:

• Mu-receptors: the main pain-blocking receptors, and the source of respiratory depression, euphoria, and physical dependence.
• Beta-receptors: modulate pain transmission by reacting with enkephalins in the periphery.
• Kappa-receptors: some analgesia, pupillary constriction, sedation, and dysphoria.
• Sigma-receptors: pupillary dilation, hallucinations, and psychoses with narcotic use.

That gives three drug classes. Narcotic agonists react with CNS opioid receptors to produce analgesia, sedation, or euphoria, and they are controlled substances because they carry dependence potential. Narcotic agonists-antagonists stimulate some opioid receptors while blocking others, giving morphine-like analgesia with less abuse potential but more psychotic-like reactions. Narcotic antagonists bind opioid receptors without activating them, blocking opioid effects and reversing an overdose.

Narcotic Agonists

Narcotic agonists act on specific CNS opioid receptors to produce analgesia, euphoria, and sedation. Use them for moderate to severe acute or chronic pain, as preoperative medication, as part of combination therapy for severe chronic pain, and intraspinally for intractable pain.

Across age groups: safety in children is not established, and only codeine, fentanyl (except transdermal), hydrocodone, meperidine, and morphine carry pediatric dosing guidelines. Naloxone is the antidote for narcotic overdose and reversal of narcotic effects. Reassure adults that abuse from acute-pain use is remote, and teach them to ask for pain medication before the pain becomes severe. Use caution in pregnancy and lactation. The narcotics used in labor are morphine, meperidine, and oxymorphone. All narcotic agonists are pregnancy category B except oxycodone (category C), which makes oxycodone the choice if one is needed in pregnancy. Older adults are more vulnerable to adverse effects from existing conditions, so set up safety measures (side rails, call light, ambulation assistance).

Pharmacokinetics

Here are the characteristic interactions of narcotic agonists and the body in terms of absorption, distribution, metabolism, and excretion:

Contraindications and cautions: allergy to narcotic agonists; diarrhea from toxic poisons (GI depression increases absorption and toxicity); respiratory dysfunction; recent GI or GU surgery, acute abdomen, or ulcerative colitis (worsened by GI depression); head injury, alcoholism, delirium tremens, or cerebral vascular disease (worsened by CNS effects); liver or renal dysfunction (impairs metabolism and excretion); and pregnancy or lactation.

Adverse effects run by system: CNS light-headedness, dizziness, psychoses, anxiety, fear, hallucinations, pupil constriction, and impaired mental processing; GI nausea, vomiting, constipation, and biliary spasm; GU ureteral spasm, urinary retention, hesitancy, and loss of libido; sweating and physical and psychological dependence. The dangerous one is narcotic-induced respiratory center depression with apnea, cardiac arrest, and shock.

Interactions: barbiturates, phenothiazines, and MAOIs raise the likelihood of respiratory depression, hypotension, and sedation or coma. Combining tapentadol, the newest agonist (it also blocks norepinephrine reuptake in the CNS), with an SSRI, MAOI, TCA, or St. John's Wort risks life-threatening serotonin syndrome. Methylnaltrexone bromide (Relistor) treats opioid-induced constipation in palliative-care patients no longer responding to traditional laxatives.

Narcotic Agonists-Antagonists

These act on certain opioid receptors while blocking others. They deliver morphine-like analgesia with less abuse potential, which makes them useful for chronic pain in patients prone to narcotic dependence. Use them for moderate to severe pain, as preanesthetic medication, and to supplement surgical anesthesia.

Across age groups: safety in children is not established, but the agonist-antagonist of choice for children older than age 13 is buprenorphine. Naloxone remains the overdose antidote. Adult and older-adult guidance matches the agonists: reassure on abuse risk, teach early dosing, use caution in pregnancy and lactation, and set safety measures for older adults.

Pharmacokinetics

Here are the characteristic interactions of narcotic agonists-antagonists and the body in terms of absorption, distribution, metabolism, and excretion:

Contraindications and cautions: allergy; physical dependence on narcotics (withdrawal can be precipitated); COPD or other respiratory dysfunction; MI, CAD, or hypertension (worsened by cardiac stimulation); renal or hepatic dysfunction; and pregnancy or lactation. Nalbuphine is specifically contraindicated in patients allergic to sulfites because of cross-hypersensitivity.

Adverse effects mirror the agonists by system (CNS, GI, GU, sweating, dependence), with narcotic-induced respiratory depression, apnea, and suppression of the cough reflex.

Interactions: barbiturates, phenothiazines, and MAOIs raise respiratory depression, hypotension, and sedation or coma risk. Tripelennamine combined with pentazocine increases hallucinogenic and euphoric effects ("Ts and Blues"). Methylnaltrexone bromide (Relistor) treats opioid-induced constipation in palliative-care patients no longer responding to traditional laxatives.

Narcotic Antagonists

Narcotic antagonists bind opioid receptors without activating them, blocking opioid effects and reversing respiratory depression and sedation. Use them for complete or partial reversal of narcotic depression and to diagnose suspected opioid overdose. Naloxone is the prototype, and the FDA notes its effect can wear off before the opioid clears, so emergency care and repeat dosing may still be needed (FDA, Information about Naloxone and Nalmefene).

Across age groups: safety in children is not established, and naloxone is the antidote for narcotic overdose and reversal. Adult guidance matches the other classes, with caution in pregnancy and lactation. Older adults need safety measures for existing conditions.

Pharmacokinetics

Here are the characteristic interactions of narcotic antagonists and the body in terms of absorption, distribution, metabolism, and excretion:

Contraindications and cautions: allergy; pregnancy or lactation; narcotic addiction (precipitates withdrawal); and cardiovascular disease (worsened by reversal of the opioid's depressive effects).

Adverse effects: CNS excitement and reversal of analgesia; CV tachycardia, blood pressure changes, dysrhythmias, and pulmonary edema. Acute narcotic abstinence syndrome brings nausea, vomiting, sweating, tachycardia, hypertension, tremulousness, and anxiety. Give a naloxone challenge before naltrexone to avoid acute reactions.

There are no significant drug-drug interactions with narcotic antagonists.

Nursing Considerations: Narcotic Agents

Assessment is shared across all three narcotic classes. Screen for the cautions and contraindications above (drug allergy, respiratory dysfunction, MI and CAD, narcotic-addiction history, hepatorenal dysfunction). Do a baseline pain assessment to gauge therapy. Perform a thorough physical (CNS, vital signs, bowel sounds, urine output; add neurological status and respiratory rate and rhythm for antagonists, plus an ECG to evaluate cardiac effects). Monitor liver and kidney function for dose adjustment and toxicity. Common nursing diagnoses: impaired gas exchange from respiratory depression, disturbed sensory perception and risk for injury from CNS effects, constipation from GI effects, and (for antagonists) decreased cardiac output and acute pain from withdrawal and CV effects.

When giving an agonist or agonist-antagonist, run baseline and periodic pain assessments and adjust the plan as needed. Keep a narcotic antagonist and assisted-ventilation equipment ready before any IV dose. Time analgesic doses so relief stays ahead of the pain. Add non-pharmacologic measures (breathing exercises, back rubs, stress reduction), comfort measures like small frequent meals for GI upset, and safety measures (lighting, raised side rails). Teach the patient the drug, its indication, and the adverse effects to watch for.

When reversing an overdose with an antagonist, maintain an open airway and provide artificial ventilation and cardiac massage as needed, and give vasopressors as ordered. Give the naloxone challenge before naltrexone because of the serious risk of acute withdrawal, and confirm the patient has been narcotic-free for 7 to 10 days before starting naltrexone to prevent severe withdrawal. Provide comfort and safety measures and teach the regimen.

Evaluate by monitoring the response to therapy (pain relief and sedation, or reversal of opioid effects and treatment of alcohol dependence for antagonists), watching for adverse effects, confirming the patient can name the drug and its effects, and checking compliance.

Antimigraine Agent: Ergot Derivatives

Antimigraine agents treat the pounding headache that comes with nausea, vomiting, and light sensitivity. Two classes exist: ergot derivatives and triptans. Ergot derivatives decrease pulsation of the cranial arteries and constrict cranial blood vessels by blocking alpha-adrenergic and serotonin-receptor sites, which reduces hyperperfusion of the basilar artery vascular bed. Use them to prevent or abort migraine or vascular headaches. Ergotamine was the drug of choice for migraine before triptans were developed.

Across age groups: neither antimigraine class is recommended for children, since ergot derivatives carry many adverse effects and there is not enough clinical experience to recommend triptans for children. Assess the headache carefully in adults before starting, and remember both classes are contraindicated in pregnancy and lactation. In older adults, antimigraine agents readily worsen chronic conditions, so use extreme caution, the lowest possible dose, and strict safety precautions.

Pharmacokinetics

Here are the characteristic interactions of ergot derivates and the body in terms of absorption, distribution, metabolism, and excretion:

Contraindications and cautions: allergy to ergot derivatives; CAD, hypertension, or peripheral vascular disease (worsened by CV effects); impaired liver function; pregnancy or lactation; pruritus (worsened by drug-induced vascular constriction); and malnutrition (drugs stimulate the CTZ and can cause severe GI reactions). Ergotism in infants presents as vomiting, diarrhea, and seizures.

Adverse effects: CNS numbness, tingling of the extremities, and muscle pain; CV pulselessness, weakness, chest pain, arrhythmia, localized edema and itching, and MI; direct CTZ stimulation causing GI upset, nausea, vomiting, and diarrhea. Ergotism itself brings nausea, vomiting, severe thirst, hypoperfusion, chest pain, blood pressure changes, confusion, drug dependency, and a withdrawal syndrome.

Interactions: beta-blockers increase the risk of peripheral ischemia and gangrene.

Antimigraine Agent: Triptans

Triptans are a newer antimigraine class that causes cranial vascular constriction and relieves migraine pain by binding serotonin receptors. They treat acute migraine only and are not used for prevention. Age-group, contraindication, and pregnancy guidance match the ergot derivatives above.

Pharmacokinetics

Here are the characteristic interactions of triptans and the body in terms of absorption, distribution, metabolism, and excretion:

Contraindications and cautions: allergy to triptans; pregnancy or lactation; active CAD (worsened by the drug's vessel-constricting effect); and renal or hepatic dysfunction.

Adverse effects: CNS numbness, tingling, burning, feelings of coldness or strangeness, dizziness, weakness, myalgia, and vertigo; CV blood pressure alterations and chest tightness or pressure; GI dysphagia and abdominal discomfort.

Interactions: ergot-containing drugs risk prolonged vasoactive reactions, and an MAOI raises vasoconstriction risk if a triptan is used within 2 weeks of MAOI discontinuation.

Nursing Considerations: Antimigraine Agents

Screen for the cautions and contraindications above (drug allergy, MI and CAD history, hepatorenal dysfunction). Do a thorough physical (neurological status, vital signs) for baseline, and monitor liver and kidney function for dose adjustment and toxicity. Likely diagnoses: decreased cardiac output and acute pain from CV effects, and risk for injury from CNS effects.

Give the drug at the first sign of headache to relieve an acute migraine, not to prevent one, since these are not preventive agents. Monitor for extremity numbness and tingling, which signals vascular constriction. Provide comfort and safety measures (lighting, raised side rails) and teach the patient the drug, its indication, and the adverse effects to watch for.

Evaluate by monitoring relief of the acute migraine, watching for CV adverse effects, confirming the patient can name the drug and its effects, and checking compliance.

Frequently Asked Questions

Why keep naloxone and ventilation equipment at the bedside before giving an opioid? The dose-limiting danger of a narcotic agonist is respiratory depression that can progress to apnea. Naloxone reverses opioid-induced respiratory depression by knocking opioids off their receptors, so it and airway support stay within reach for every IV opioid (FDA, Information about Naloxone and Nalmefene).

Does one dose of naloxone fix an overdose? Not reliably. Naloxone restores breathing, but its action can fade before the opioid is cleared, so the patient can slip back into depression. SAMHSA advises calling emergency services and watching for a return of symptoms, with repeat doses as needed (SAMHSA, Opioid Overdose Reversal Medications).

What is the difference between a narcotic agonist, an agonist-antagonist, and an antagonist? Agonists activate opioid receptors for full analgesia and carry the most dependence and respiratory risk. Agonists-antagonists stimulate some receptors while blocking others, giving morphine-like relief with less abuse potential but more psychotic-type reactions. Antagonists like naloxone bind receptors without activating them, purely to block or reverse opioid effects.

Why can't a triptan or ergot derivative be given during an active cardiac event? Their mechanism is vasoconstriction of cranial vessels, and that same effect can constrict coronary arteries. Both classes are contraindicated in active coronary artery disease, uncontrolled hypertension, and any acute cardiac picture.

Why give a naloxone challenge before starting naltrexone? Naltrexone in an opioid-dependent patient precipitates acute withdrawal. A naloxone challenge first, plus confirming the patient has been opioid-free for 7 to 10 days, prevents triggering severe abstinence syndrome.

Are these drugs safe in pregnancy? Most narcotic agonists are pregnancy category B, with oxycodone (category C) the choice if one is needed, but use is cautioned. Triptans and ergot derivatives are contraindicated in pregnancy and lactation.