Pharmacology Guide
Pain management
Date Created
Date Modified
Acetylsalicylic (Aspirin) | Acetaminophen (Tylenol) | Darvocet | Sumatriptan (Imitrex)
Percodan | Ibuprofen | Hydrocodone & Acetaminophen (Vicodin) | Fiorinal
Acetylsalicylic
|
Aspirin |
Mechanism of Action
|
Like other non-steroidal antiinflammatory drugs (NSAIDs),the action is believed to be due to the inhibition of prostaglandin synthesis. |
Therapeutic Use
|
Treatment of mild pain including, headache, arthralgia (joint pain) and myalgia (muscle pain). Treatment of fever. |
Absorption
|
Absorbed rapidly, partly from the stomach but mostly from the upper small intestine. Peak value in about 2 hours. |
Metabolism
|
Rapidly metabolized in plasma to salicylic acid which is an active metabolite. Salicylic acid then undergoes oxidation and conjugation with glucuronic acid and glycine in the liver. |
Half-life
|
15-20 minutes. |
Average Daily Dose (adult)
|
650 mg every four hours. |
Adverse Effects
|
GI irritation and bleeding, aggravation of peptic ulcer, and Reye's Syndrome. |
Drug Interaction
|
It can displace other drugs from plasma proteins such as sulfonamides. It may produce bleeding in patients receiving anticoagulants. |
Contraindication
|
Contraindicated in patients with chicken pox, peptic ulcer, hypersensitivity to aspirin, and/or in patients with bleeding disorders. |
Acetaminophen
|
Tylenol |
Mechanism of Action
|
Believed to be due to the inhibition of prostaglandin synthesis. However, unlike aspirin it does not exert an antiinflammatory effect. |
Therapeutic Use
|
Mild pain and fever. |
Absorption
|
Peak effect in 30-60 minutes. Rapidly absorbed in the gastrointestinal tract. |
Metabolism
|
Primarily conjugated in the liver with glucuronic acid, sulfuric acid or cysteine. A small amount is hydroxylated. A small portion undergoes cytochrome P-450 oxidation to form a toxic metabolite that can damage the liver. |
Half-life
|
2 Hours. |
Average Daily Dose (adult)
|
1,000-3,000 mg. Should not exceed 4,000 mg. |
Adverse Effects
|
The drug is usually well tolerated. Skin and other allergic reactions can occur, rarely. However, the main toxicity with acetaminophen is the liver damage that can occur with large doses. Hepatotoxicity can result from a single dose of 10-15 g. Higher doses can be fatal. |
Drug Interaction
|
Chronic alcohol abusers may be at increased risk for liver toxicity. |
Contraindication
|
Renal (kidney) insufficiency and anemia. Use with caution during pregnancy. |
Darvocet
|
Darvocet |
Mechanism of Action
|
Propoxyphene is a mild narcotic analgesic structurally related to methadone. |
Therapeutic Use
|
Mild to moderate pain. |
Absorption
|
Peak plasma concentrations are reached in 2-2 1/2 hours. |
Metabolism
|
Metabolized in the liver by microsomal enzymes. |
Half-life
|
6-12 hours. |
Average Daily Dose (adult)
|
100 mg propoxyphene napsylate and 650 mg acetaminophen every 4 hours. |
Adverse Effects
|
Dizziness, sedation, nausea and vomiting. Some of these adverse reactions may be alleviated if the patient lies down. |
Drug Interaction
|
The CNS-depressant effect of propoxyphene is additive with that of other CNS depressants, including alcohol. Propoxyphene may slow the metabolism of a concomitantly administered drug. |
Contraindication
|
Hypersensitivity to propoxyphene or acetaminophen. |
Sumatriptan
|
Imitrex |
Mechanism of Action
|
Has been demonstrated to be a selective agonist for a vascular 5-hydroxytryptamine receptor subtype. |
Therapeutic Use
|
Acute migraine attacks with or without aura. Acute treatment of cluster headaches. |
Absorption
|
Peak effect in about 2 hours after oral administration and 12 minutes after subcutaneous injection. Incomplete absorption. |
Metabolism
|
Metabolized by monoamine oxidase (MAO) to form indole acetic acid. |
Half-life
|
2 1/2 hours. |
Average Daily Dose (adult)
|
25 mg tablet taken with fluids; the maximum single dose recommended is 100 mg. |
Adverse Effects
|
Tingling sensation, burning sensation, a feeling of warmth, a feeling of heaviness or pressure in the head. Some patients experience tightness in the chest. Could precipitate a heart attack in susceptible individuals and therefore should not be given to individuals with a history of ischemic heart disease or angina. |
Drug Interaction
|
Imitrex tablets should not be used within 24 hours of an ergotamine-containing or ergot-type medication like dihydroergotamine or methysergide. |
Contraindication
|
Use with caution during lactation, in individuals with hepatic (liver) or renal (kidney) problems and in persons with heart conditions. Any patients who are sensitive to sumatriptan. |
Percodan
|
Percodan |
Mechanism of Action
|
The principal ingredient, oxycodone, is a semisynthetic narcotic analgesic with multiple actions qualitatively similar to those of morphine; the most prominent of these involve the central nervous system . Like other narcotic analgesics this drug acts by stimulating opioid receptors in the brain. |
Therapeutic Use
|
Treatment of moderate to moderately severe pain. |
Absorption
|
Readily absorbed from the gastrointestinal tract but is significantly metabolized by the liver before reaching the systemic circulation. |
Metabolism
|
Metabolized in the liver by P-450 enzymes. May also undergo glucuronic conjugation. |
Half-life
|
Unknown. |
Average Daily Dose (adult)
|
5-10 mg every 4-5 hours. |
Adverse Effects
|
Lightheadedness, dizziness, sedation, nausea and vomiting.Can produce drug dependence. Constipation. (See above for adverse effects of aspirin.) |
Drug Interaction
|
CNS depressant effects may be additive with that of other CNS depressants. Aspirin may enhance the effect of anticoagulants and inhibit the uricosuric effects of uricosuric agents. |
Contraindication
|
Hypersensitivity to oxycodone or aspirin. |
Ibuprofen
|
Motrin |
Mechanism of Action
|
Inhibits prostaglandin synthesis like other NSAIDS. |
Therapeutic Use
|
Treatment of mild to moderate pain. |
Absorption
|
Peak effect 1-2 hours. Well absorbed. |
Metabolism
|
More than 90% of an ingested dose is excreted in the urine as metabolites. |
Half-life
|
2 hours. |
Average Daily Dose (adult)
|
400 mg three or four times a day. |
Adverse Effects
|
Gastrointestinal disturbances, nausea, epigastric pain, heartburn and gastrointestinal bleeding. |
Drug Interaction
|
Possible displacement of warfarin (coumadin) from plasma proteins to increase the toxicity of warfarin. |
Contraindication
|
Should not be used in patients with hypersensitivity to Ibuprofen or other NSAIDs such as aspirin. |
Hydrocodone & Acetaminophen
|
Vicodin |
Mechanism of Action
|
Hydrocodone is a semisynthetic narcotic analgesic and antitussive with multiple actions qualitatively similar to those of codeine. Same as other narcotic analgesics (see Oxycodone & Aspirin above). |
Therapeutic Use
|
Treatment of moderate to moderately severe pain. |
Absorption
|
Readily absorbed from the gastrointestinal tract but is significantly metabolized by the liver before reaching the systemic circulation. |
Metabolism
|
Metabolized in the liver by P-450 enzymes. May also undergo glucuronic conjugation. |
Half-life
|
4 hours. |
Average Daily Dose (adult)
|
One or two tablets every four to six hours as needed for pain. |
Adverse Effects
|
May cause dependence due to narcotic ingredient. Lightheadedness, dizziness, sedation, nausea and vomiting. |
Drug Interaction
|
Patients receiving other narcotic analgesics, antihistamines, antipsychotics, antianxiety agents or other CNS depressants (including alcohol) concomitantly with Vicodin tablets may exhibit an additive CNS depression. |
Contraindication
|
Contraindicated during lactation. Should not be administered to patients who have previously exhibited hypersensitivity to hydrocodone or acetaminophen. |
Fiorinal
|
Fiorinal |
Mechanism of Action
|
Butalbital, aspirin and caffeine. Combines the analgesic properties of aspirin with the anxiolytic and muscle relaxant properties of butalbital. |
Therapeutic Use
|
Treatment of tension headaches. |
Absorption
|
Well absorbed from the gastrointestinal tract. Peak blood levels are reached in 1 .5 hours. |
Metabolism
|
Metabolized by the P-450 enzymes in the liver. |
Half-life
|
Caffeine 4.9 hours. Aspirin, see above. Butalbital 35-88 hours. |
Average Daily Dose (adult)
|
One or two tablets every 4 hours. |
Adverse Effects
|
Drowsiness and dizziness. G.I. irritation for aspirin. |
Drug Interaction
|
Alcohol and other CNS depressants may produce an additive CNS depression and should be avoided. |
Contraindication
|
Patients with an aspirin allergy. |
These brief pharmaceutical summaries do not include all information important for patient use and should not be used as a substitute for professional medical advice. Consult the prescribing doctor and read package inserts before using these or any other medications or supplements.
CDER
U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
Public Health Service
National Institutes of Health
Bell, K., Kraus, E., & Zasler, N. (1999). Medical management of posttraumatic headaches: pharmacological and physical treatment. Journal of Head Trauma Rehabilitation . 14(1), 34-48.
Orza, F. (2000). Neuropathic pain: Review of mechanisms and Pharmacologic management. Neurorhabilitation . 14(1), 15-24.
