analgesics

Analgesic Drugs

Understanding Pain

• Most common symptom prompting people to seek health care

• Occurs when tissue damage activates free nerve endings of peripheral nerves

• Cerebral cortex analyzes messages and determines actions

• Activation of opiate receptors in CNS inhibits pain transmission

Understanding Pain• Pain is a subjective experience• People differ in their perceptions, behavior

and tolerance of pain• Stressors increase pain• Diversionary activities tend to decrease pain-

– deep breathing, listening to music, visual imagery, others?

• Acute pain can be super-imposed on chronic pain

• Try alternative measures for pain control in addition to drugs

• Promote circulation and musculoskeletal function

• Use heat or cold as ordered

• Relieve pain ASAP

• Administer analgesic before pain producing activities

• Use the least amount of the mildest drug likely to be effective

Types of Pain

• Acute pain

• Chronic pain

• Superficial pain

• Deep pain

• Opioid-any derivative of opium plant or any synthetic drug that imitates natural narcotics

• Opioid agonists-include opium derivatives and synthetic drugs w/similar properties (Kee p.332)

• Decrease pain without losing consciousness• Opioid antagonists

– Block effects of opioid agnoists– Used to reverse drug reactions-RD, CNS

depression– Narcan (always keep antagonist nearby)

NARCOTICSOPIOIDS

• Opioid agonists– Any route– Inhalation uncommon– Absorbed from GI tract– Transmucosal / intrathecal fast acting– IV provides most rapid and almost immediate – Sub Q and IM delayed absorption

• Poor circulation can cause further delay

– Metabolized extensively in the liver• Administration of meperedine > 48 hours increases

risk of neurotoxicity and seizures from buildup

Pharmacodynamics• Reduce pain by binding to opiate receptors in

PNS/CNS• Stimulation of opiate receptors-mimic effects of

endorphins –the body’s naturally occurring opiates

• Cause dilation of blood vessels in head, neck, face – could result in increased cranial pressure

• With the exception of Demerol, suppress cough center to have antitussive effect

• Adverse / Side effects include constipation, respiratory depression, nausea, vomiting, urinary retention, orthostatic hypotension

• Morphine – relieve dyspna r/t pulmonary edema

• Nursing process– Assess pain before and after administration– Monitor for adverse reactions / side effects– Monitor for tolerance dependence

• Shortened duration of effect

– Evaluate respiratory status before each dose• Respiratory depression• Restlessness

Mechanisms by Which Opioid Analgesics Work

• Reduce the perception of pain sensation

• Produce sedation

• Decrease emotional upsets associated with pain

Characteristics of Opioid Analgesics

• Most are Schedule II or III drugs

• Morphine (MSO4) is the prototype

• May be given PO, IV, IM, SQ, or topically

• Oral drugs undergo significant first-pass metabolism

• Metabolized by liver and excreted in urine

• Exert CNS effects• Use cautiously in clients with renal or

hepatic disease, respiratory depression or increased intracranial pressure

• Exert depressant effect on GI tract• Not recommended for prolonged periods

of use except with chronic pain or malignant diseases

Morphine• Naturally occurring opium alkaloid• Used to relieve severe pain• Maximum analgesia occurs in 10-20 minutes

with IV route• Controlled released tablets given for chronic

pain• May be given intrathecally or epidurally• Route determines time interval or frequency of

administration

Hydromorphone(Dilaudid)

• Synthetic derivative of morphine

• Same actions, uses, adverse effects as morphine

• More potent on a mg per mg basis

• More effective orally than morphine

• Effects last longer than morphine

Meperidine(Demerol)

• Synthetic drug similar to morphine

• Dose of 100mg is equivalent to Morphine 10mg

• Has shorter duration

• Has less respiratory depression and little antitussive effect

• Causes less smooth muscle spasm

Codeine

• Naturally occurring opium alkaloid

• Used for milder pain

• Acts as an antitussive (found in cough meds)

• Often combined with acetaminophen

• Preferred analgesic with head trauma

Oxycodone

• Semisynthetic derivative of codeine

• Used to relieve moderate pain

• More potent and more likely to produce abuse than codeine

• Available in combination with acetaminophen

Opioid Antagonists• Reverse or block analgesia, CNS and

respiratory depression of opioid agonists• Compete with opioids for opioid receptor sites

in brain• Do not relieve depressant effects of anti-

anxiety drugs or antipsychotics• Naloxone - oldest, most commonly known• Nalmefene - newer with longer duration• Naltrexone - used in maintenance of opiate

free states in opiate addicts

Client Teaching For Opioid Analgesics

• Narcotics may be alternated with a non-narcotic analgesic

• If pain relief not achieved notify physician

• Do not drink alcohol or take other drugs that cause drowsiness

• Do not smoke, cook, drive a car or operate machinery after taking

• Constipation is a common adverse effect

• Do not crush or chew long acting tablets

• Decrease dose or omit if adverse effects occur

Use In Older Adults• Use cautiously if debilitated or hepatic, renal

or respiratory impairment

• Start with lower dose and increase gradually

• Give less often?

• Give opioid analgesic with short half-life (Oxycodone)

• Monitor for sedation or confusion

• Monitor urinary output

• Assess ability to self-medicate

Characteristics of Withdrawal From Opiates

• Generalized body aches

• Insomnia• Lacrimation• Rhinorrhea• Perspiration• Pupil dilation

• Piloerection• Anorexia• N/V/D• Increased vital signs• Abdominal and other

muscle cramps

Treatment Of Withdrawal Syndrome

• Gradually reduce the opioid over several days

• Substitute methadone and slowly reduce dose over a longer time

• Clonidine reduces withdrawal symptoms

• Salicylates-produce peripheral blood vessel dilation– Most common pain reliever– Control pain– Reduce fever-stimulate hypothalmus– Reduce inflammation– ASA is oldest nonnarcotic analgesic– Bonus effect-inhibits platelet aggregrate– Guideline

• Use lowest dose that produces analgesia• Highly protein bound-can interfere w/other drugs

– Heparin,methotrexate, oral antidiabetic meds, insulin

NONNARCOTICSSALICYLATES

• Adverse reactions– Hearing loss– Diarrhea– Thirst– Sweating– Tinnitus– Confusion– Dizziness– Impaired vision– Hyperventilation– Reye’s syndrome-when given to children (do not use < 12

yrs old)

• Common side effects– Gastric distress– Bleeding tendencies– NVD

• Give w/food• May crush except enteric coated• Hold and notify MD for bleeding• Stop ASA 5-7 days before elective

surgery• Salicylate hypersensitivity

– Tinnitus or hearing loss– Vertigo– Bronchospasm– Urticaria– Need to avoid prunes, raisins, paprika,

licorice

• Acetaminophen– Antipyretic and analgesic– IS NOT ANTI INFLAMMATORY– Drug of choice for children with flulike

symptoms– Risk of liver disease

• Phenytoin, barbituates, INH, ETOH– Rarely cause GI distress-may cause LIVER

toxicity• Monitor total daily dose (adults 4g max.)

ACETAMINOPHEN

Phenazopyridine hydrochloride– Pyridium-now OTC– Dye used in commercial coloring-analgesic

effect on urinary tract– Relieves pain, burning, itching, urgency,

• Teach– Urine orange– Stains fabric-contact lenses– Notify in ineffective

Anti Inflammatory Drugs

• Anti inflammatory agents– Reduce body temperature– Relief of pain– Anticoagulant (ASA)– Reduce inflammation

• ASA – oldest

• NSAIDS- reduce inflammation & pain for arthritic conditions

• Inhibit enzyme COX

• OTC

–Ibuprofen, Motrin, Nuprin, Advil, Medipren

–Naproxen (Aleve)

–Motrin only available in 200 mg form

•MD must prescribe higher dose

• Second generation NSAIDS

–COX-2 inhibitors

• COX 1 inhibitor

–Decreased protection of lining of stomach

–Clotting time decreased-benefit cardiovascular patients

• NSAIDS– Inhibit prostaglandin synthesis

• Prostaglandins produced / released in inflammatory disorders

– Ankylosing spondylitis– Moderate to severe arthritis– Osteoarthritis– Acute gouty arthritis– Dysmenorrhea– Migranes– Bursitis, tendonitis

• Adverse reactions– Abdominal pain, bleeding– Anorexia– Diarrhea, nausea– Ulcers– Liver toxicity– Drowsiness– Headache– Tinnitus– Confusion– Vertigo– Depression– Blood in urine, bladder infection, kidney necrosis– Sodium & water retention– Heart failure– Pedal edema

• Nursing implications– CBC, platelet count, PT– Monitor hepatic / renal function– Bronchospasm– Monitor for s/s of bleeding– Take w/meals– Avoid alcohol

Corticosteroids– prednisone / prednisolone /

dexamethasone

– Suppresses components of inflammatory process at the injured site

– NOT THE DRUG OF CHOICE FOR ARTHRITIC CONDITIONS

– USED TO CONTROL FLARE UPS

– Must taper dose when D/C

DMARDS-disease modifying antirheumatic drugs– Toxic – Alter disease process– Gold/Gold Salts

• IM/PO• Used for relief of symptoms• Immunosuppressive agents-used when

antiinflammatories do not work-cytoxan, methotexrate/cancer drugs

• Antimalarials-when all other tx fails

Antiinflammatory Gout Drugs– “gouty arthritis”– Urinary calculi– Gouty nephrophaty

• Increase fluid intake• Avoid foods rich in purine - organ meats,

sardines, salmon, gravy, legumes• Avoid alcohol, caffeine, large doses of vitamin C• Zyloprim - inhibits final steps of uric acid • Colchicine - first drug, inhibits migration of

leukocytes to the inflamed site

Propionic Acid Derivatives

• Ibuprofen (Motrin) - prototype; ketoprofen (Orudis), naproxen (Naprosyn)

• Used as anti-inflammatory agents in gout, arthritis, tendonitis

• Used as analgesic for dysmenorrhea, episiotomy, minor trauma

• Used as antipyretic

• Better tolerated than ASA but more expensive

• Similar adverse affects as with ASA

• May lead to renal impairment

• Inhibits platelets only while drug molecules in bloodstream

• Combined with other drugs

Acetic Acid Derivatives

• Indomethacin (Indocin) - prototype; Tolmetin (Tolectin), Sulindac (Clinoril)

• Used to treat moderate to severe rheumatoid arthritis, osteo-arthritis, gouty arthritis, bursitis, pericarditis for anti-inflammatory effects

• Prescription drug• Has increased incidence and severity of

adverse effects

Client Teaching Guidelines • Take ASA and NSAIDS with full glass of

water and food

• Drink 2-3 quarts of fluid daily with NSAIDS

• Report signs of bleeding

• Avoid or minimize alcoholic beverages

• Do not take more than prescribed amount

• Do not take more that 3 days for fever or 10 days for pain

• Read labels of other OTC medications