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    Willow

    Willow

    Uses

    Common names:
    Willow, Willow Bark
    Botanical names:
    Prunus serotina, Salix alba

    Parts Used & Where Grown

    The willow tree grows primarily in central and southern Europe, although it is also found in North America. The bark is used to make herbal extracts.

    What Are Star Ratings?

    Our proprietary ?Star-Rating? system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.

    For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.

    3 Stars Reliable and relatively consistent scientific data showing a substantial health benefit.

    2 Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.

    1 Star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.

    This supplement has been used in connection with the following health conditions:

    Used for Why
    2 Stars
    Low Back Pain
    Take an extract supplying 240 mg of salicin daily
    Learn More

    Willow bark is traditionally used for pain and conditions of inflammation. According to one controlled clinical trial, use of high amounts of willow bark extract may help people with low back pain. One trial found 240 mg of salicin from a willow extract to be more effective than 120 mg of salicin or a placebo for treating exacerbations of low back pain.3

    2 Stars
    Osteoarthritis
    Take an extract supplying 240 mg of salicin per day
    Learn More
    Willow has anti-inflammatory and pain-relieving properties. Although pain relief from willow supplementation may be slow in coming, it may last longer than pain relief from aspirin . One double-blind trial found that a product containing willow along with black cohosh , guaiac (Guaiacum officinale, G. sanctum), sarsaparilla , and aspen (Populus spp.) bark effectively reduced osteoarthritis pain compared to placebo.4 Another trial found that 1,360 mg of willow bark extract per day (delivering 240 mg of salicin) was somewhat effective in treating pain associated with knee and/or hip osteoarthritis.5
    1 Star
    Bursitis
    Refer to label instructions
    Learn More

    While there have been few studies on herbal therapy for bursitis, most practitioners would consider using anti-inflammatory herbs that have proven useful in conditions such as rheumatoid arthritis . These would include boswellia , turmeric , willow , and topical cayenne ointment.

    1 Star
    Pain
    Refer to label instructions
    Learn More

    As early as 1763, use of willow bark to decrease pain and inflammation was reported.6 Its constituents are chemically related to aspirin . These constituents may decrease pain by two methods: by interfering with the process of inflammation, and by interfering with pain-producing nerves in the spinal cord.7 No human studies have investigated the pain-relieving potential of willow bark, and questions have been raised as to the actual absorption of willow bark?s pain-relieving constituents.8 The potential pain-reducing action of willow is typically slower than that of aspirin.

    1 Star
    Rheumatoid Arthritis
    Refer to label instructions
    Learn More

    Although willow is slow acting as a pain reliever, the effect is thought to last longer than the effect of willow?s synthetic cousin, aspirin . One double-blind trial found that willow bark combined with guaiac, sarsaparilla , black cohosh , and poplar (each tablet contained 100 mg of willow bark, 40 mg of guaiac, 35 mg of black cohosh, 25 mg of sarsaparilla, and 17 mg of poplar) relieved pain due to RA better than placebo over a two-month period.9 The exact amount of the herbal combination used in the trial is not given, however, and patients were allowed to continue their other pain medications. Clinical trials on willow alone for RA are lacking. Some experts suggest that willow may be taken one to four weeks before results are noted.10

    Traditional Use (May Not Be Supported by Scientific Studies)

    Willow bark was used traditionally by herbalists for fever, headache, pain , and rheumatic complaints.1 In the late 19th century, the constituent salicylic acid was isolated from willow bark and went on to become the model for the development of aspirin (acetylsalicylic acid).2

    How It Works

    Common names:
    Willow, Willow Bark
    Botanical names:
    Prunus serotina, Salix alba

    How It Works

    The glycoside salicin, from which the body can split off salicylic acid, is thought to be the source of the anti-inflammatory and pain-relieving actions of willow.11 The analgesic actions of willow are typically slow to develop but may last longer than the effects of standard aspirin products. One trial has found that a combination herbal product including 100 mg willow bark taken for two months improved functioning via pain relief in people with osteoarthritis .12 Another trial found that 1360 mg of willow bark extract per day (delivering 240 mg of salicin) for two weeks was somewhat effective in treating pain associated with knee and/or hip osteoarthritis .13 Use of high amounts of willow bark extract may also help people with low back pain. One four-week trial found 240 mg of salicin from a willow extract was effective in reducing exacerbations of low back pain.14

    How to Use It

    Willow extracts standardized for salicin content are available. The commonly recommended intake of salicin has been 60?120 mg per day.15 However, newer studies suggest a higher salicin intake of 240 mg per day may be more effective for treating pain.16 A willow tea can be prepared from 1/4?1/2 teaspoon (1?2 grams) of bark boiled in about 7 ounces (200 ml) of water for ten minutes. Five or more cups (1250 ml) of this tea can be drunk per day. Tincture, 1?1 1/2 teaspoons (5?8 ml) three times per day, is also occasionally used.

    Interactions

    Common names:
    Willow, Willow Bark
    Botanical names:
    Prunus serotina, Salix alba

    Interactions with Supplements, Foods, & Other Compounds

    At the time of writing, there were no well-known supplement or food interactions with this supplement.

    Interactions with Medicines

    Certain medicines interact with this supplement.

    Types of interactions: Beneficial Adverse Check

    Replenish Depleted Nutrients

    • none

    Reduce Side Effects

    • none

    Support Medicine

    • Metoclopramide

      Salicylic acid is a compound formed in the body from either aspirin or willow bark (Salix alba). Taking metoclopramide before aspirin or willow bark results in higher concentrations of salicylic acid and greater pain relief in people suffering from an acute migraine headache.17 Controlled studies are necessary to confirm the benefit of this interaction.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

    Reduces Effectiveness

    • Diclofenac

      Willow bark (Salix alba) contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. The administration of aspirin to individuals taking diclofenac results in a significant reduction in blood levels of diclofenac.22 Though there are no studies investigating interactions between willow bark and diclofenac, people taking the drug should avoid the herb until more information is available.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Ketoprofen

      Willow bark (Salix alba) contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. The interaction between salicylic acid and ketoprofen is complex. While it may enhance the effectiveness of ketoprofen, salicylic acid also speeds its elimination from the body.30 Consequently, people taking ketoprofen should avoid herbal products that contain willow bark.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Nadolol

      The active compound in willow (Salix alba), salicin, is converted to salicylic acid in the body. Taking salicylates with other beta-adrenergic blocking drugs has resulted in decreased absorption of the drugs.37 Therefore, until more is known about the interaction between willow and nadolol, they should not be taken at the same time.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

    Potential Negative Interaction

    • Bismuth Subsalicylate

      Bismuth subsalicylate contains salicylates. Various herbs including meadowsweet  (Filipendula ulmaria), poplar (Populus tremuloides), willow  (Salix alba), and wintergreen (Gaultheria procumbens) contain salicylates as well. Though similar to aspirin , plant salicylates have been shown to have different actions in test tube studies.18 Furthermore, salicylates are poorly absorbed and likely do not build up to levels sufficient to cause negative interactions that aspirin might.19 No reports have been published of negative interactions between salicylate-containing plants and aspirin or aspirin-containing drugs.20 Therefore concerns about combining salicylate-containing herbs remain theoretical, and the risk of causing problems appears to be low.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Celecoxib

      Willow bark (Salix alba) contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. Taking aspirin and celecoxib together increases the likelihood of developing stomach and intestinal ulcers.21 Though no studies have investigated a similar interaction between willow bark and celecoxib, people taking the drug should avoid the herb until more information is available.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Diclofenac-Misoprostol

      White willow bark (Salix alba) contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. The administration of salicylates like aspirin to individuals taking oral NSAIDs may result in reduced blood levels of NSAIDs.23 Though no studies have investigated interactions between white willow bark and NSAIDs, people taking NSAIDs should avoid the herb until more information is available.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Diflunisal

      White willow bark (Salix alba) contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. The administration of salicylates like aspirin to individuals taking oral NSAIDs may result in reduced blood levels of NSAIDs.24 Though no studies have investigated interactions between white willow bark and NSAIDs, people taking NSAIDs should avoid the herb until more information is available.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Etodolac

      White willow bark (Salix alba) contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. The administration of salicylates like aspirin to individuals taking oral NSAIDs may result in reduced blood levels of NSAIDs.25 Though no studies have investigated interactions between white willow bark and NSAIDs, people taking NSAIDs should avoid the herb until more information is available.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Fenoprofen

      White willow bark (Salix alba) contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. The administration of salicylates like aspirin to individuals taking oral NSAIDs may result in reduced blood levels of NSAIDs.26 Though no studies have investigated interactions between white willow bark and NSAIDs, people taking NSAIDs should avoid the herb until more information is available.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Flurbiprofen

      White willow bark (Salix alba) contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. The administration of salicylates like aspirin to individuals taking oral NSAIDs may result in reduced blood levels of NSAIDs.27 Though no studies have investigated interactions between white willow bark and NSAIDs, people taking NSAIDs should avoid the herb until more information is available.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Ibuprofen

      White willow bark (Salix alba) contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. The administration of salicylates like aspirin to individuals taking oral NSAIDs may result in reduced blood levels of NSAIDs.28 Though no studies have investigated interactions between white willow bark and NSAIDs, people taking NSAIDs should avoid the herb until more information is available.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Indomethacin

      White willow bark (Salix alba) contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. The administration of salicylates like aspirin to individuals taking oral NSAIDs may result in reduced blood levels of NSAIDs.29 Though no studies have investigated interactions between white willow bark and NSAIDs, people taking NSAIDs should avoid the herb until more information is available.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Ketoprofen

      Willow bark (Salix alba) contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. The interaction between salicylic acid and ketoprofen is complex. While it may enhance the effectiveness of ketoprofen, salicylic acid also speeds its elimination from the body.31 Consequently, people taking ketoprofen should avoid herbal products that contain willow bark.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Ketorolac

      White willow bark (Salix alba) contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. The administration of salicylates like aspirin to individuals taking oral NSAIDs may result in reduced blood levels of NSAIDs.32 Though no studies have investigated interactions between white willow bark and NSAIDs, people taking NSAIDs should avoid the herb until more information is available.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Live Influenza Vaccine Intranasal

      Willow bark (Salix alba) contains salicin, a substance similar to aspirin . Aspirin should not be given to children receiving live influenza virus due to the possible link to Reye's syndrome. The same adverse interaction result could theoretically happen if children were to take a willow-containing product following FluMist®.

    • Meclofenamate

      White willow bark (Salix alba) contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. The administration of salicylates like aspirin to individuals taking oral NSAIDs may result in reduced blood levels of NSAIDs.33 Though no studies have investigated interactions between white willow bark and NSAIDs, people taking NSAIDs should avoid the herb until more information is available.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Mefenamic Acid

      White willow bark (Salix alba) contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. The administration of salicylates like aspirin to individuals taking oral NSAIDs may result in reduced blood levels of NSAIDs.34 Though no studies have investigated interactions between white willow bark and NSAIDs, people taking NSAIDs should avoid the herb until more information is available.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Meloxicam

      White willow bark (Salix alba) contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. The administration of salicylates like aspirin to individuals taking oral NSAIDs may result in reduced blood levels of NSAIDs.35 Though no studies have investigated interactions between white willow bark and NSAIDs, people taking NSAIDs should avoid the herb until more information is available.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Nabumetone

      White willow bark (Salix alba) contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. The administration of salicylates like aspirin to individuals taking oral NSAIDs may result in reduced blood levels of NSAIDs.36 Though no studies have investigated interactions between white willow bark and NSAIDs, people taking NSAIDs should avoid the herb until more information is available.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Naproxen

      White willow bark (Salix alba) contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. The administration of salicylates like aspirin to individuals taking oral NSAIDs may result in reduced blood levels of NSAIDs.38 Though no studies have investigated interactions between white willow bark and NSAIDs, people taking NSAIDs should avoid the herb until more information is available.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Oxaprozin

      White willow bark contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. The administration of salicylates like aspirin to individuals taking oral NSAIDs may result in reduced blood levels of NSAIDs.39 Though no studies have investigated interactions between white willow bark and NSAIDs, people taking NSAIDs should avoid the herb until more information is available.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Repaglinide

      Willow bark contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. Taking aspirin together with repaglinide enhances the blood-sugar-lowering effects of the drug,40 which might result in unwanted side effects. Controlled research is needed to determine whether taking willow bark together with repaglinide might produce similar effects.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Salsalate

      Willow bark contains salicin, which is related to aspirin . Salsalate, salicin, and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. Taking aspirin at the same time as other salicylate drugs can result in adverse effects, such as ringing in the ears , dizziness, headache, confusion, and diarrhea .41 Though there are no studies specifically investigating an interaction between willow bark and salsalate, people taking salsalate should probably avoid using the herb until more information is available.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Sulindac

      White willow bark contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. The administration of salicylates like aspirin to individuals taking oral NSAIDs may result in reduced blood levels of NSAIDs.42 Though no studies have investigated interactions between white willow bark and NSAIDs, people taking NSAIDs should avoid the herb until more information is available.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Tolmetin

      White willow bark (Salix alba) contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. The administration of salicylates like aspirin to individuals taking oral NSAIDs may result in reduced blood levels of NSAIDs.43 Though no studies have investigated interactions between white willow bark and NSAIDs, people taking NSAIDs should avoid the herb until more information is available.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Valdecoxib

      White willow bark (Salix alba) contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. The administration of salicylates like aspirin to individuals taking oral NSAIDs may result in reduced blood levels of NSAIDs.44 Though no studies have investigated interactions between white willow bark and NSAIDs, people taking NSAIDs should avoid the herb until more information is available.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Zafirlukast

      Willow bark (Salix alba) contains salicin, a substance similar to aspirin . Research has shown that aspirin significantly increases blood levels of zafirlukast,45 which would increase the likelihood of side effects from zafirlukast. The same thing could theoretically happen if people took willow bark along with zafirlukast, although no studies have investigated this specific interaction. People may want to avoid combining willow bark with zafirlukast due to the possibility of increased side effects.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

    Explanation Required

    • Piroxicam

      Willow bark contains salicin, which is related to aspirin . Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. Taking aspirin significantly lowers blood levels of piroxicam and increases the potential for adverse side effects.46 Though no studies have investigated interactions between willow bark and piroxicam, people taking the drug should avoid the herb until more information is available.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers? package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a supplement with your doctor or pharmacist.

    Side Effects

    Common names:
    Willow, Willow Bark
    Botanical names:
    Prunus serotina, Salix alba

    Side Effects

    As with aspirin, some people may experience stomach upset from taking willow. Although such symptoms are less likely from willow than from aspirin , people with ulcers and gastritis should, nevertheless, avoid this herb.47 Again, as with aspirin, willow should not be used to treat fevers in children since it may cause Reye?s syndrome.

    There is one published report of a severe allergic reaction (anaphylaxis) occurring in a person who took a supplement that contained willow bark.48 The possibility of allergy to willow bark should be considered by anyone who is allergic to aspirin or other salicylates.

    References

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    2. Foster S. 101 Medicinal Herbs. Loveland, CO: Interweave Press, 1998, 210?1.

    3. Chrubasik S, Eisenberg E, Balan E, et al. Treatment of low back pain exacerbations with willow bark extract: A randomized double-blind study. Am J Med 2000;109:9?14.

    4. Mills SY, Jacoby RK, Chacksfield M, Willoughby M. Effect of a proprietary herbal medicine on the relief of chronic arthritic pain: a double-blind study. Br J Rheum 1996;35:874?88.

    5. Schmid B, Tschirdewahn B, Kątter I, et al. Analgesic effects of willow bark extract in osteoarthritis: results of a clinical double-blind trial. Fact 1998;3:186.

    6. Hedner T, Everts B. The early clinical history of salicylates in rheumatology and pain. Clin Rheumatol 1998;17:17?25.

    7. Cherng CH, Wong CS, Ho ST. Spinal actions of non-steroidal anti-inflammatory drugs. Acta Anaesthesiol Sin 1996;34:81?8.

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    9. Mills SY, Jacoby RK, Chacksfield M, Willoughby M. Effect of a proprietary herbal medicine on the relief of chronic arthritic pain: A double-blind study. Br J Rheum 1996;35:874?8.

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    12. Mills SY, Jacoby RK, Chacksfield M, Willoughby M. Effect of a proprietary herbal medicine on the relief of chronic arthritic pain: A double-blind study. Br J Rheum 1996;35:874?8.

    13. Schmid B, Tschirdewahn B, Kątter I, et al. Analgesic effects of willow bark extract in osteoarthritis: results of a clinical double-blind trial. Fact 1998;3:186.

    14. Chrubasik S, Eisenberg E, Balan E, et al. Treatment of low back pain exacerbations with willow bark extract: A randomized double-blind study. Am J Med 2000;109:9?14.

    15. Blumenthal M, Busse WR, Goldberg A, et al. (eds). The Complete Commission E Monographs: Therapeutic Guide to Herbal Medicines. Boston, MA: Integrative Medicine Communications, 1998, 230.

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    22. Davies NM, Anderson KE. Clinical pharmacokinetics of diclofenac. Therapeutic insights and pitfalls. Clin Pharmacokinet 1997;33:184?213.

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    35. Olin BR, ed. Central Nervous System Drugs, Analgesics and Anti-inflammatory Drugs, Nonsteroidal Anti-inflammatory Agents, In Drug Facts and Comparisons. St. Louis, MO: Facts and Comparisons, 1993, 1172?90.

    36. Olin BR, ed. Central Nervous System Drugs, Analgesics and Anti-inflammatory Drugs, Nonsteroidal Anti-inflammatory Agents, In Drug Facts and Comparisons. St. Louis, MO: Facts and Comparisons, 1993, 1172?90.

    37. Burnham TH, ed. Cardiovascular Agents, Antiadrenergics/Sympatholytics, Beta-Adrenergic Blocking Agents. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, 2000, 467?79.

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    39. Olin BR, ed. Central Nervous System Drugs, Analgesics and Anti-inflammatory Drugs, Nonsteroidal Anti-inflammatory Agents, In Drug Facts and Comparisons. St. Louis, MO: Facts and Comparisons, 1993, 1172?90.

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    41. Sifton DW, ed. Physicians Desk Reference. Montvale, NJ: Medical Economics Company, Inc., 2000, 1661?2.

    42. Olin BR, ed. Central Nervous System Drugs, Analgesics and Anti-inflammatory Drugs, Nonsteroidal Anti-inflammatory Agents, In Drug Facts and Comparisons. St. Louis, MO: Facts and Comparisons, 1993, 1172?90.

    43. Olin BR, ed. Central Nervous System Drugs, Analgesics and Anti-inflammatory Drugs, Nonsteroidal Anti-inflammatory Agents, In Drug Facts and Comparisons. St. Louis, MO: Facts and Comparisons, 1993, 1172?90.

    44. Olin BR, ed. Central Nervous System Drugs, Analgesics and Anti-inflammatory Drugs, Nonsteroidal Anti-inflammatory Agents, In Drug Facts and Comparisons. St. Louis, MO: Facts and Comparisons, 1993, 1172?90.

    45. Kelloway JS. Zafirlukast: the first leukotriene-receptor antagonist approved for the treatment of asthma. Ann Pharmacother 1997;31(9):1012?21.

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