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Nonnarcotic Analgesics Salicylates and Nonsalicylates

Pain can be defined as an unpleasant sensory and emotional experience that is associated with actual or potential tissue damage. Pain is subjective, and the patient’s report of pain should always be taken seri-ously. Pain management in acute and chronic illness is an important responsibility of the nurse. Many nurses consider pain as the fifth vital sign and assessment of pain just as important as the assessment of temperature,pulse, respirations, and blood pressure. Accurate assess-ment of pain is necessary if pain management is to be
effective. Patients with pain are often undertreated.Basically there are three types of pain: acute pain,chronic pain associated with malignant disease, and chronic pain not associated with malignant disease.Acute pain is of short duration and lasts less than 3 to 6 months. Intensity of acute pain is from mild to severe.
Causes of acute pain include postoperative pain, proce-dural pain, and traumatic pain. Acute pain usually sub-sides when the injury heals.Chronic pain lasts longer than 6 months and ranges in intensity from mild to severe. Chronic pain associated with malignancy includes the pain of cancer, acquired immunodeficiency syndrome (AIDS), multiple sclerosis sickle cell disease, and end-stage organ system failure. The exact cause of chronic pain of a nonmalignan nature may or may not be known. This type of pain includes the pain associated with various neuropathic and musculoskeletal disorders such as headaches fibromyalgia, rheumatoid arthritis, and osteoarthritis.The next three chapters deal with drugs used in the management of pain: the nonnarcotic analgesics (salicylates, nonsalicylates [acetaminophen], and the non steroidal anti-inflammatory drugs) and the narcotic analgesics.
The nonnarcotic analgesics are a group of drugs used to relieve pain without the possibility of causing physical dependency, which can occur with the use othe narcotic analgesics. The nonnarcotic analgesics can be divided into the salicylates, nonsalicylates (aceta minophen), and the nonsteroidal anti-inflammatory drugs (NSAIDs). There are a number of combination nonnarcotic analgesics that are available over the counter and by prescription. The NSAIDs have emerged as important drugs in the treatment of the chronic pain and inflammation associated with disor-ders such as rheumatoid arthritis or osteoarthritis.Examples of NSAIDs include celecoxib (Celebrex) and rofecoxib (Vioxx).

SALICYLATES


The salicylates include aspirin (acetylsalicylic acid)and related drugs, such as magnesium salicylate and sodium salicylate. The salicylates have analgesic (relieves pain), antipyretic (reduces elevated body tem-perature), and anti-inflammatory effects. All the salicy-lates are similar in pharmacologic activity; however,aspirin has a greater anti-inflammatory effect than the other salicylate


ACTIONS

The manner in which salicylates relieve pain and reduce inflammation is not fully understood. It is thought that the analgesic action of the salicylates is due to the inhibition of prostaglandins. Prostaglandins are fatty acid derivatives found in almost every tissue of the body and body fluid. Release of prostaglandin is thought to increase the sensitivity of peripheral pain receptors.
The inhibitory action of the salicylates on the prostaglandins is also thought to account for the anti-inflammatory activity. Salicylates lower an elevated body temperature by dilating peripheral blood vessels,which in turn cools the body.
Aspirin more potently inhibits prostaglandin synthe-sis and has greater anti-inflammatory effects that the other salicylates. In addition, aspirin also prolongs the bleeding time by inhibiting the aggregation (clumping)
of platelets. When the bleeding time is prolonged, it takes a longer time for the blood to clot after a cut, surgery, or other injury to the skin or mucous membranes. The other salicylates do not have as great an effect on platelets as does aspirin. This effect of aspirin on the platelets is irreversible and lasts for the life of the platelet (7–10 days).

USES

The salicylate nonnarcotic analgesics are used for the following reasons:
• Relief of mild to moderate pain;
• Reduction of elevated body temperature (except for diflunisal which is not used as an antipyretic);
• Treatment of inflammatory conditions, such as rheumatoid arthritis, osteoarthritis, and rheumatic fever;
• Reduction of the risk of myocardial infarction in those with unstable angina or previous myocardial
infarction (aspirin only);
• Reduction of the risk of transient ischemic attacks or strokes in men who have had transient ischemia of the brain due to fibrin platelet emboli (aspirin only). This use has been found to be effective only in men (not women).

ADVERSE REACTIONS

Gastric upset, heartburn, nausea, vomiting, anorexia,and gastrointestinal bleeding may occur with salicylate use. Although these drugs are relatively safe when taken as recommended on the label or by the primary health care provider, their use can occasionally result in more serious reactions. Some individuals are allergic to aspirin and the other salicylates. Allergy to the salicy-lates may be manifested by hives, rash, angioedema,bronchospasm with asthma-like symptoms, and anaphylactoid reactions.
Loss of blood through the gastrointestinal tract occurs with salicylate use. The amount of blood lost is insignificant when one normal dose is taken. However,use of these drugs over a long period, even in normal doses, can result in a significant blood loss.Salicylate toxicity produces a condition called sali-cylism.
Mild salicylism usually occurs with repeated administration of large doses of a salicylate.This condition is reversible with reduction of the drug dosage.

CONTRAINDICATIONS


The salicylates are contraindicated in patients with known hypersensitivity to the salicylates or the NSAIDs and during pregnancy. Aspirin is a Pregnancy Category D drug and may produce adverse maternal effects (ie, anemia, postpartum hemorrhage, and pro-longed gestation or labor). Maternal aspirin used may also cause adverse fetal effects, such as low birth weight, intracranial hemorrhage in premature infants,stillbirths, and neonatal death. Other salicylates (ie, salsalate and magnesium salicylate) are Pregnancy Category C drugs. Because the salicylates prolong bleeding time, they are contraindicated in those with bleeding disorders or bleeding tendencies. These include patients with gastrointestinal bleeding (due to any cause), blood dyscrasias, and those receiving anti-coagulant or antineoplastic drugs. Children or teenagers with influenza or chickenpox should not take the salicylates, particularly aspirin, because their use appears to be associated with Reye’s syndrome (a life-threatening condition characterized by vomiting and lethargy, progressing to coma).

PRECAUTIONS


The salicylates are used cautiously in patients with hepatic or renal disease, preexisting hypoprothrombine-mia, or vitamin K deficiency and during lactation. The drugs are also used with caution in patients with gas-trointestinal irritation such as peptic ulcers and in patients with mild diabetes or gout.

INTERACTIONS

Food containing salicylate (curry powder, paprika,licorice, prunes, raisins, and tea) may increase the risk of adverse reactions. Coadministration of the salicylates with activated charcoal decreases the absorption of the salicylates. Antacids may decrease the effects of the salicylates. Coadministration with the carbonic anhydrase inhibitors increases the risk of salicylism.Aspirin may increase the risk of bleeding during heparin administration. Coadministration with the NSAIDs may increase NSAID blood levels.

NONSALICYLATES


The major drug classified as a nonsalicylate is aceta-minophen (Tylenol, Datril, Panadol). Acetaminophen is the only drug of its kind available in the United States at this time. It is the most widely used aspirin substitute for patients who are allergic to aspirin or who experi-ence extreme gastric upset when taking aspirin.
Acetaminophen is also the drug of choice for treating children with fever and flu-like symptoms.

ACTIONS


Acetaminophen is a nonsalicylate nonnarcotic analgesic whose mechanism of action is unknown. Like the sali-cylates, acetaminophen has analgesic and antipyretic activity. However, acetaminophen does not possess anti-inflammatory action and is of no value in the treatment of inflammation or inflammatory disorders.

USES

Acetaminophen is used to relieve mild to moderate pain and to reduce elevated body temperature (fever). This drug is particularly useful for those with aspirin allergy and bleeding disorders, such as bleeding ulcer or hemo-philia, those receiving anticoagulant therapy, and those who have recently had minor surgical procedures.
Although acetaminophen has no anti-inflammatory action, it may be used to relieve the pain and discomfort associated with arthritic disorders.

ADVERSE REACTIONS

Acetaminophen causes few adverse reactions when used as directed on the label or recommended by the pri-mary health care provider. Adverse reactions associated with the use of acetaminophen usually occur with chronic use or when the recommended dosage is exceeded. Adverse reactions to acetaminophen include
skin eruptions, urticaria (hives), hemolytic anemia,pancytopenia (a reduction in all cellular components of the blood), hypoglycemia, jaundice (yellow discoloration of the skin), hepatotoxicity (damage to the liver), and hepatic failure (seen in chronic alcoholics taking the drug).
Acute acetaminophen poisoning or toxicity can occur after a single 10- to 15-g dose of  acetaminophen.Dosages of 20 to 25 g may be fatal. With excessive dosages the liver cells necrose or die. Death can occur due to liver failure. The risk of liver failure increases in patients who are chronic alcoholics.
Signs of acute acetaminophen toxicity include the following:
• Nausea
• Vomiting
• Confusion
• Liver tenderness
• Hypotension
• Arrhythmias
• Jaundice
• Acute hepatic and renal failure

CONTRAINDICATIONS, PRECAUTIONS,
AND INTERACTIONS


Hypersensitivity to acetaminophen is a contraindication.Hepatotoxicity has occurred in chronic alcoholics after therapeutic dosages. The individual taking acetaminophen should avoid alcohol if taking more than an occasional dose of acetaminophen and avoid taking acetaminophen concurrently with the salicylates or the
NSAIDs. Acetaminophen is classified as Pregnancy Category B and is used cautiously during pregnancy and lactation. If an analgesic is necessary, it appears safe for short-term use. The drug is used cautiously in patients with severe or recurrent pain or high or continued fever because this may indicate a serious illness that is untreated. If pain persists for more than 5 days or if red-ness or swelling is present, the primary health care provider should be consulted.
Acetaminophen may alter blood glucose test results,causing falsely lower blood glucose values. Use with the barbiturates, hydantoins, isoniazid, and rifampin may increase the toxic effects and possibly decrease the therapeutic effects of acetaminophen. The effects of the loop diuretics may be decreased when administered
with acetaminophen. Hepatotoxicity has occurred in chronic alcoholics who are taking moderate doses of acetaminophen.
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Ditulis oleh: Unknown - Thursday 22 April 2010