Wednesday, April 4, 2012

Analgesic



OPIOID ANALGESICS (narcotic analgesics)

·         A group of drugs that has the ability to relieve moderate-to-severe pain.
·         Opioids produce their major effects on the central nervous system and gastrointestinal tracts. They generally produce analgesic effects by binding to specific opioid receptors at the supraspinal and spinal levels.
·         It has potential ability to produce physical dependence therefore it has been classified by FDA under controlled substances.
·         Indication: For moderate-to-severe pain that is more or less constant in duration.
o    Indicated for patients with chronic pain due to terminal cancer or acute pain following surgery, trauma or myocardial infarction.
o    Used as an anesthetic premedication or as an adjuct in general anesthesia
o    Other uses:
§  Cough suppression (antitussive)
§  Decreases GIT motility (e.g severe diarrhea)
§  For sedation
·         Contraindication: pregnancy, existing intestinal obstruction, hypersensitivity to morphine, decreased respiratory reserve (e.g asthma, emphysema), brain damage, simultaneous treatment of antidepressants, biliary colic, low blood pressure and hypovolemic shock

Classification of Opioid Agents:

Strong Agonist
Mild-to-Moderate Agonist
·   Used to treat severe pain
·   Used to treat moderate pain
morphine (Duramorph®)
codeine
methadone (Dolophine®)
oxycodone (Percodan®)
meperidine (Demerol®)
hydrocodone (Hycodan®)
fentanyl (Duragesic®, Sublimaze®)
propoxyphene (Darvon®)
levorphanol (Levo-Dromoran®)
hydromorphone (Dilaudid®)
Mixed Agonist-Antagonists
·      has lesser adverse effects and reduces the risk of dependence
Antagonists
butorphanol (Stadol®)
For opioid overdose, addiction
nalbuphine (Nubain®)
naloxone (Narcan®)
naltrexone (Trexan®)
pentazocine (Talwin®)

Side Effects:

·   Nausea
·         Urinary retention
·   Constipation
·         Vomiting

Nursing Considerations:

ü  Assessn patient’s pain before and after dose.
ü  Administer the narcotic before pain reaches its peak to maximize the effectiveness of the drug
ü  Observe for severe adverse reactions due to opioid use such as respiratory depression, mental clouding & sense of euphoria.
ü  Monitor I&O. It should be at least 600 ml/day
ü  Check for any signs of constipation. Administer laxatives as prescribed
ü  Make sure naloxene (Narcan®) is readily available in case of overdose
ü  Fentanyl combined with baclofen can prolong the analgesic effect of fentanyl.
ü  Educate patient not to take any alcohol or CNS depressant for it might result to respiratory depression if narcotics are prescribed/administered.
ü  May use non-pharmacological method to prolong effects.

NON-OPIOID ANALGESICS (non-narcotic analgesics)

Acetominophen (Tylenol)

·         Widely used in the treatment of non-inflammatory conditions associated with mild-to-moderate pain and in patients who had a history of or currently have gastric damage.
·         Acetaminophen does appear to have the same effects with aspirin or other NSAIDs in terms of analgesic and antipyretic effects. However, it has NO anti-inflammatory and anti-coagulant properties.
·         There has been no incidence of Reye Syndrome in the use of acetaminophen as compared to aspirin or NSAID use.
·         Its analgesic effect is brought about by the inhibition of prostaglandin synthesis in the CNS. In addition, it decreases fever by inhibiting the effects of pyrogens on the hypothalamic heating regulation center.
·         Contraindications: intolerance to tartrazine (yellow dye #5), , alcohol, table sugar, saccharin; Hypersensitivity, liver failure
·         Example: Tylenol®, Datril®

Adverse Effects: High dose and prolong use of acetaminophen can lead to hepatotoxicity, hepatic seizures, liver failure and hemolytic anemia

Nursing Consideration:

o    Instruct patient not to use with alcohol.
o    Educate the patient about the risk of hepatic complication if high doses of acetaminophen is consumed.
o    Check serum acetaminophen level when toxicity is suspected. Toxic level: > 50 mcg/mL; > 200 mcg/mL indicated hepatotoxicity
o    Administer N-acetylcysteine (Mucomyst®) in cases of acetaminophen overdose. – an antidote to prevent or lessen hepatic injury which may occur following the ingestion of a potentially hepatotoxic quantity of acetaminophen.

Nonsteroidal Anti-inflammatory Drugs (NSAIDs)

·         A group of drugs that has anti-inflammatory, anti-coagulant, antipyretic and analgesic effects.
·         NSAIDs are able to produce their effects by inhibiting cyclooxygenase enzyme. As a result, synthesis of prostaglandin and thromboxane are decreased/inhibited.
·         Indication: Prescribed to patients with:
o    mild-to-moderate pain (e.g headache, muscular pain)
o    inflammatory conditions (e.g arthritic conditions, bursitis)
o    pain and cramping associated with primary dysmenorrhea
o    pain following minor/intermediate surgery
o    fever (adult); contraindicated to children < 6 mos.
o    a history or concurrent occlusive arterial diseases (to prevent platelet induced thrombus formation)
·         Contraindication: hypersensitivity to salicylates or NSAIDs; hemophilia, bleeding ulcers or hemorrhagic states
·         Examples:

Common NSAIDs (as approved by FDA)
Aspirin/ASA (Ecotrin®)
flurbirofen (Ansaid®)
celecoxib (Celebrex®)
ibuprofen (Motrin®)
meloxicam (Mobic®)
indomethacin (Indocin®)
nabumetone (Relafen®)
ketoprofen (Oruvail®)
etodolac (Lodine®, Lodine XL®)
ketorolac (Toradol®)
fenoprofen (Nalfon®)
mefenamic  Acid (Ponstel®)
diclofenac (Cataflam®, Voltaren®)
oxaprozin (Daypro®)
diflunisal (Dolobid®)
piroxicam (Feldene®)
naproxen (Naprosyn®, Anaprox®)
sulindac (Clinoril®)
tolmetin (Tolectin®)


Side effects:

·         Minor stomach discomfort
·         Upper gastrointestinal hemorrhage and ulceration
·         Hepatotoxicity - in high-doses of aspirin-like drugs
·         Heart attack or stroke. Aspirin does not increase the chance of a heart attack
·         High blood pressure
·         Kidney problems including kidney failure
·         Life-threatening skin/allergic reactions


Nursing Consideration:

ü  NSAIDs should never be used before or after a heart surgery.
ü  Inform the patient not to take NSAIDs if he has an asthma attack, hives or other allergic reactions with aspirin.
ü  Take precautions when administering NSAIDs to patients with hemophilia, vitamin K deficiency and liver disease. Prolonged bleeding times can be problematic.
ü  May increase bleeding if used with warfarin
In patients administered with methotraxate, a cancer drug, precaution on ASA use. It decreases renal excretion of methotraxate, which could result 

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