Analgesics: Nursing pharmacology

Definitions & Key takeaways

Analgesics are drugs that reduce pain. They work by either blocking the transmission of pain signals or by reducing inflammation. There are many different types of analgesics available, and they can be divided into two main groups: Non-opioid analgesic agents which include non-steroidal anti-inflammatory drugs (NSAIDs); and opioid analgesics.

NSAIDs include ibuprofen, aspirin, and naproxen. These drugs work by blocking the action of cyclooxygenase (COX), an enzyme that is involved in the production of inflammatory mediators. Opioid analgesics include morphine, codeine, and fentanyl. These drugs work by binding to opioid receptors in the brain, which reduces the perception of pain.

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Introduction0:00–0:47

Analgesics, also commonly known as painkillers, are medications primarily used to relieve pain, such as a headache, muscle and neuropathic pain, as well as pain related to trauma and fractures.
Analgesics can be subdivided into two main groups: non-opioid analgesics, and opioid analgesics. Keep in mind though that there are a number of other medications that primarily serve other purposes, but can be used as analgesics.
These medications include antidepressants like amitriptyline, anticonvulsants like gabapentin, and corticosteroids like dexamethasone, as well as local anesthetics like lidocaine.
Now, let’s start with non-opioid analgesics, which include non-steroidal anti-inflammatory drugs or NSAIDs, and acetaminophen.
NSAIDs inhibit the enzyme cyclooxygenase or COX, both in the central nervous system and peripheral tissues. Now, there are two types of COX enzymes.

Non-opioid analgesics - NSAIDs0:47–1:48

The first one is called COX-1, which is indirectly involved in platelet aggregation, production of protective mucus in the stomach and vasodilation of the renal vasculature.
On the flip side, COX-2 is only active in inflammatory cells and vascular endothelium during inflammation, and is involved in the production of small pro-inflammatory compounds like prostaglandins.
Now, a very commonly used NSAID is acetylsalicylic acid, often referred to as aspirin, which is taken orally. On the other hand, non-aspirin NSAIDs can be further classified as non-selective COX inhibitors that act on both COX-1 and COX-2, like ibuprofen, naproxen and ketorolac; and selective COX-2 inhibitors, like celecoxib.
Non-aspirin NSAIDs are most often administered orally, but some can also be given intramuscularly, intravenously, topically, or rectally.Now the most important side effects of NSAIDs include gastrointestinal problems, such as gastritis, gastric ulcers, or even bleeding, and that’s a boxed warning!

NSAIDs - Side effects1:48–2:24

Additionally, chronic use of NSAIDs can impair normal blood flow in the kidneys and may increase the risk of hyperkalemia, nephropathy, or renal failure.
It’s important to note that these side effects are less frequent with selective COX-2 inhibitors. Other side effects that can occur in clients taking NSAIDs include headache, drowsiness and dizziness, as well as severe hypersensitivity reactions, such as anaphylaxis and Stevens-Johnson Syndrome.
NSAIDs should not be used during the third trimester of pregnancy, as well as in clients with renal or hepatic impairment.

NSAIDs - Contraindications & cautions2:24–3:36

Also, NSAIDs should be avoided in individuals who have experienced allergic reactions to one NSAID because they can experience the same reaction when taking other NSAIDs, due to cross-hypersensitivity.
NSAIDs also have a boxed warning in the setting of coronary artery bypass graft, due to the increased risk of adverse thrombotic events leading to myocardial infarction or stroke.
A specific contraindication for aspirin is children with viral infections, as it is associated with Reye syndrome, which is characterized by liver damage and progressive hepatic encephalopathy.
The only exception is the treatment of children with Kawasaki disease, which is a condition associated with inflammation of blood vessels.
Lastly, ketorolac has a few boxed warnings; it is contraindicated for children, while for adults, it indicated for only short term use, no longer than 5 days, and clients older than 65 require dosage adjustment; ketorolac is also contraindicated in clients with renal disease, cerebrovascular bleeding, and a history of peptic ulcers; and finally, it is contraindicated during labor.Moving on, acetaminophen is often referred to as paracetamol, and can be administered orally, rectally or intravenously.

Non-opioid analgesics - Acetaminophen3:36–4:07

This medication is not classified as an NSAID because it reversibly inhibits COX enzymes only in the central nervous system.
For that reason, acetaminophen is preferred to treat fever or pain in clients with bleeding disorders, peptic ulcers and individuals allergic to aspirin.
Also, it’s the first-line therapy for children with fever or pain, especially when it’s associated with a viral infection.

Acetaminophen - Side effects4:07–4:44

Now, oral acetaminophen is metabolized in the liver, so it can precipitate acute liver failure in some clients and intravenous acetaminophen poses an increased risk for medication errors and overdose.
An important boxed warning is to limit acetaminophen from all sources, including cold medicines, to no more than 4 grams/day.
Early symptoms of acetaminophen overdose include nausea, vomiting, and abdominal pain; while late symptoms include jaundice, coagulopathy, hepatic encephalopathy, and even renal failure.
Acetaminophen is contraindicated in clients with hepatic disease.Now, switching gears, opioid analgesics are primarily administered orally, intravenously, intramuscularly, or subcutaneously.

Opioid analgesics4:44–5:35

Other routes of administration include transdermal, epidural, intrathecal, and topical. These medications primarily work by activating opioid receptors mu, delta, and kappa in the brain.
Now, based on the effect on opioid receptors, opioid analgesics are subdivided into three main groups. The first group covers full agonists and it includes morphine, methadone, meperidine, codeine, oxycodone, and fentanyl; while the second group includes partial agonists, such as tramadol.
Finally, the third group includes mixed agonist-antagonists, such as buprenorphine, which has an agonist effect on kappa opioid receptors, and a weak antagonist effect on mu receptors.Common side effects include sedation, nausea, vomiting, constipation, as well as urinary retention, which is typically seen in older clients.

Opioid analgesics - Side effects5:35–6:14

Also, analgesic opioids can decrease blood pressure or cause orthostatic hypotension. An important thing to keep in mind is that opioids have a number of boxed warnings, including respiratory depression, severe sedation, coma, and death.
In addition, using opioids during pregnancy can result in neonatal opioid withdrawal syndrome. Finally, a very important boxed warning is that clients can develop dependence and addiction to opioids, leading to abuse and misuse.
Contraindications to opioid analgesics include respiratory depression, head trauma, increased intracranial pressure, and clients in a coma.

Opiod analgesics - Contraindications & cautions6:14–6:37

It’s important to note that opioid analgesics should not be used in combination with other CNS depressants like alcohol, barbiturates, or benzodiazepines, since their additive effect can lead to respiratory depression, coma, and even death.Now, when caring for a client who’s experiencing pain, you can choose to administer the appropriate analgesics prescribed based on your nursing pain assessment.

Nursing considerations & client education6:37–11:22

So, before administering an analgesic medication, be sure to thoroughly assess your client’s pain, including the type of pain, along with its onset, quality, location, severity, and duration.
Then, collaborate with your client to establish their goal for pain management and their tolerable level of pain. Also be sure to document their baseline vital signs.
Always review their medical record to confirm there are no medical conditions that will require close monitoring, as well as current medications that could interact with the analgesics.
Lastly, incorporate non-pharmacological interventions for pain, such as relaxation, guided imagery and distraction, whenever possible.Okay, if your client has mild pain, a non-opioid analgesic, such as an NSAID or acetaminophen, could be administered.
Before administering an NSAID like ibuprofen, be sure to check their laboratory tests, including CBC, BUN and creatinine.
Also confirm that your client does not have a history of peptic ulcer disease. Then, administer the medication with meals or a glass of milk to help limit gastrointestinal upset.
After administration, assess for side effects like headache, dizziness, or epigastric pain, and continue to monitor their renal function, especially if you are caring for an elderly client.
If your client will be discharged home on ibuprofen, advise them to avoid drinking alcohol while taking the medication, since it can increase the risk of gastrointestinal irritation.
Lastly, advise them to report any symptoms of persistent gastric distress.On the other hand, before administering acetaminophen, pay close attention to your client’s baseline liver function.
If your client is discharged home on acetaminophen, let them know that they can take their medication with or without food.
Then, caution them to avoid drinking alcohol when taking acetaminophen, and be sure to stress the importance of taking their medication as directed; this includes reminding them to avoid taking more than 4 grams of acetaminophen in a 24-hour period from all sources, including other over the counter medications like cold medicines.
Lastly, prompt them to contact their healthcare provider if they develop side effects like nausea, vomiting and abdominal pain, which could be early signs of liver damage.Alright, when your client has moderate to severe pain, an opioid analgesic like morphine or tramadol can be administered, either by itself or combined with a non-opioid analgesic.
Before administering the medication, assess your client’s baseline level of consciousness and vital signs, paying close attention to their respiratory rate and blood pressure.
If your client’s respiratory rate is lower than 12 breaths per minute, or their blood pressure is significantly lower than their pretreatment reading, hold the medication and contact the healthcare provider right away.
After administration, continue to monitor their vital signs and level of sedation. In addition, let the healthcare provider know right away if you detect respiratory depression or if your client is not easily arousable with verbal or physical stimulation.
Also monitor closely for side effects like constipation and urinary retention, and take measures to keep your client safe from falls.
Assist your client to turn in bed, cough, and deep breathe at regular intervals while awake to decrease accumulation of respiratory secretions.
Lastly, be sure to have an opioid antagonist like naloxone readily available in the event of over-sedation or respiratory depression.
Now, if your client is discharged home on an opioid medication, advise them to take the medication exactly as prescribed, and warn them that sedation is a common side effect, so they should use caution when engaging in activities that require alertness and concentration, like driving.
Also be sure to stress the importance of avoiding alcohol while taking this medication. Explain that the hypotensive effects of opioids can be minimized by making position changes slowly; advise them to sit or lie down if they feel dizzy.
Next, remind them to increase their daily intake of fiber and fluids to avoid constipation. Lastly, explain how opioids can decrease their awareness of a full bladder, and advise them to to empty their bladder at least every 4 hours to avoid urinary retention.
Finally, after administering any analgesic medication, remember to reassess your client’s pain level and therapeutic outcome, and contact the healthcare provider if the prescribed pain management regimen is not adequately managing your client’s pain.Alright, as a quick recap… Analgesics are medications primarily used to relieve pain, and include non-opioid medications, like NSAIDs and acetaminophen, and opioid medications.

Review11:22–12:42

NSAIDs are the medication of choice for mild to moderate pain. They are contraindicated in clients with renal impairment or gastric ulcers, in children under six months of age, in clients with an active source of bleeding, or during the third trimester of pregnancy.
On the other hand, acetaminophen is typically used for mild to moderate non-inflammatory pain like headaches. Acetaminophen can be toxic to the liver, so clients are advised to limit acetaminophen from all sources, including cold medicines, to no more than 4 grams per day.
Finally, opioid analgesics are preferred for moderate to severe pain. Major side effects of opioids include respiratory depression, sedation, constipation, and urinary retention; and naloxone should be readily available to reverse severe side effects.
When caring for clients receiving analgesics for pain management, nursing considerations include conducting a thorough pain assessment, reassessment for effectiveness of the prescribed pain management regimen, and monitoring for side effects as well as the therapeutic outcome.
Client teaching centers around non-pharmacological methods of managing pain, safe self-administration, and side effects that should be reported