Pain Medications
Over the counter pain meds-non opioid
Both acetaminophen and nonsteroidal antiinflammatory drugs (NSAIDs) (ibuprofen and others)
reduce fever and relieve pain caused by muscle aches and stiffness,
Acetaminophen
works on the parts of the brain that receive the "pain messages."
Reduce fever and relieve pain caused by muscle aches and stiffness
Dose excess is easy because in many products
Causes hepatic damage—DO NOT exceed 3-4 g/day
NSAIDS
reduce inflammation (swelling and irritation); reduce fever and relieve pain caused by muscle
aches and stiffness
work by reduction of prostaglandisn (hormone-like substances that cause pain)
available in a prescription strength
Analgesic ceiling—more medication will not give more pain relief
Gastric upset
Platelet dysfunction and bleeeding
All NSAIDS inhibit the enzyme cyloxygenase (COX)
COX-2 is produced mainly at the site of tissue injury; therefore COX-2 inhibitors like Celebrex
(celecoxib) may produce better pain relief for inflammatory pain like arthritis. Some COX-2
inhibitors have been removed from the market because of a high association with
cardiovascular events.
Opioids—can be agonist, antagonist, or mixed; most of the commonly used one are
agonists.
Opioids are narcotic pain medications that contain natural, synthetic or semi-synthetic opiates.
Opioids are often used for acute pain, such as short-term pain after surgery.
Better for nociceptive pain than neuropathic pain; No analgesic ceiling
Adding acetominophen or NSAID limits the daily dose that can be given
Some examples of opioids include:
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Morphine; Dilaudid (hydromorphone) usually given IV; IV narcotics have an onset of action of
about 2-5 minutes, peak in 20 minutes. Rapid pain relief but don’t last as long as IM or PO.
Need to know the onset and peak so you know when it is safe to give the next dose.
Respiratory depression is an important observation. Respiratory rate below 10 may require
Narcan (naloxone—an opioid antagonist). Dilaudid is much more potent than morphine,
therefore the dose is much lower. While both of these are used for severe pain;
hydromorphone is generally reserved for the most severe pain.
Naloxone given IV will provide instant relief of respiratory depression, but you will have a
patient in pain; therefor use lowest possible dose; will wear off before the narcotic; anticipate
return of respiratory depression
Morphine: Oral forms exist but require higher doses because or the first pass effect .
Fentanyl—potent, rapid acting; patch for round the clock pain relief; generally used for cancer
pain; if have breakthrough pain may treat with additional pain medication. Also use as
anesthetic.
Oxycontin—long acting form of oxycodone; po; do not crush—
MS contin—long acting form of morphine; do not crush, patient will get all medication at once
(possibly lethal)
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Oxycodone/acetominophen (Vicodin 5 mg/500 mg, Norco 10/500); other forms of
acetominophen should not be taken because of the danger of liver toxicity
Codeine—not commonly used; may be in prescription cough medicine
Opioids are effective for severe pain and do not cause bleeding in the stomach or other parts of
the body as can other types of pain relievers
Side effects of opioids may include:
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Drowsiness, dizziness, especially in opioid naïve, goes away with long term use
Nausea, vomiting, stomach pain, especially in opioid naïve, goes away with long term use
Constipation—doesn’t go away with long term use
Itching—may or may not be a sign of allergic reaction; observe carefully; Benadryl may help
Difficulty urinating-less common
Respiratory depression—especially in narcotic naïve patients and people with preexisting
respiratory problems, but could happen in any patient
Addiction . It is rare for people to become addicted to opioids if the drugs are used to treat pain
for a short period of time.
Mixed agonist-antagonist—Talwin (pentazocine and Stadol (butorphanol)—produce less respiratory
depression; also cause more dysphoria and agitation; have an analgesic ceiling
Demerol (meperidine) only for acute pain lasting 2 days of less; long term use or high doses can cause
neurotoxicity, e.g. seizures, hyperpyrexia with delirium and death when taken with MAO inhibitors. It
is a good drug if used correctly.
Darvon—no more effective that 600 mg of aspirin.
Adjuvant Analgesic Therapy
Anticonvulsants
Anticonvulsants are drugs typically used to treat seizure disorders. Some of these medications are
shown to be effective in treating neuropathic pain and migrain headaches, as well. The exact way in
which these medicines control pain is unclear but it is thought that they minimize the effects of nerves
that cause pain. Some examples include carbamazepine (Tegretol), gabapentin (Neuronton) and
pregabalin (Lyrica).
In general they are well tolerated. The most common side effects include:
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Drowsiness
Dizziness
Fatigue
Nausea
Alpha 2 adrenergic agonists; Corticosteroids; Local anesthetics
Scheduling
Schedule for prevention or control (before pain becomes severe)
Constant chronic pain (like cancer pain) should have 24 hour dosing with addition dose
for breakthrough pain
Fast acting drugs for breakthrough pain; long acting for constant pain
Titration—start with low dose and give frequently until pain is relieved, with minimal side effects.
Must know the onset and peak of action to safely titrate a dose. For example, morphine IV has an
onset of action in 2-5 and peaks in ~ 20 minutes. Therefore in 20 minutes you are seening the full
effect; if no respiratory depression it is safe to give more. This allows us to administer morphine
even to respiratory patients
For acute pain titration over time is usually downward as the acute process is resolving and pain
becomes less severe; for cancer pain titration is often upward as tolerance develops or pain
becomes more severe
Routes
Intravenous—most commonly used for severe, acute pain—morphine or oxymorphone
Intramuscular—not commonly used in hospital; gives longer duration of action than IV; very
short term use only because of pain at site, unreliable absorption, possible abscess and with long
term use-fribrosis. Onset ~15 minutes; peak 60-90 minutes; duration 4-6 hours
Oral—mild to moderate pain; must have functioning GI tract; hydromorphone and hydrocodone;
Long acting for constant chronic pain such as as cancer pain—oxycontin, MS-contin. Morphine is
given to cancer patients po. Need 30 mg to be equivalent to 10 mg of morphine because of the
first pass effect
MS contin takes 2 hours to be effective with first dose. May need to take breakthrough
med at the same time.
On the other hand Oxycontin immediately releases 1/3 of its dose; should not take
breakthrough med wit oxycontin.
Sublingual or buccal—for amount absorbed buccal or sublingual, first pass effect not present
Rectal—good route if can’t take oral and IV access not available
Transdermal—fentynal patch is absorbed slowly and take 12-17 hours for full effect; change 4872 hours depending on patient response
Spinal—needs smaller doses; monitor carefully for overdose and infection; Inplantable pump is
sometimes used
Patient-controlled analgesia (PCA)—titrates IV MED according to patient need; giveS patient
control. Programmed for a maximum dose. May be programmed for constant delivery of set dose
with patient controlled intermittent dose. May give push for breakthrough pain.