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Contents Page 1 |
Guaifenesin (pronounced gwhy-FEN-eh-sin) is an expectorant commonly found in cough syrups, tablets, etc. Its trade name is Robitussin. Other names for guaifenesin include glyceryl guaiacolate and guaiacol glyceryl ether (9-BK). Guaifenesin is phenol derivative with a molecular weight of 198.22. It is absorbed from the gastrointestinal tract and its inactive metabolites are eliminated renally (1-BK). If you do a PubMed search, you will find that guaifenesin is given to horses that are being anesthestized for surgery. Unfortunately, horses aren't the only ones being operated on -- the government has forced manufacturers of ephedrine to add guaifenesin to their tablets in order to make it more difficult for bathtub chemists to make illegal recreational drugs. This has created a situation where obese people are being chronically exposed to rather large doses of guaifenesin. |
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How Safe Is Guaifenesin?Every now and then someone pops up in the newsgroups asking if ephedrine could cause a rash. Well, guess what? Although guaifenesin does not cause problems very often, the "U.S. Pharmacopeial Drug Information for the Health Care Professional" (USP-DI) lists rashes and hives as side effects of guaifenesin. Other side effects include headache, dizziness, nausea, vomiting, and stomach pain (1-BK). Also, according to the USP-DI, "adequate and well-controlled studies in pregnant women have not been done" and "it is not known whether guaifenesin is distributed into breast milk." We do know that one group of babies -- whose mothers took guaifenesin during the first trimester of pregnancy -- had an increased incidence of inguinal (groin) hernias. However, a couple of larger groups showed no problems that were "strongly associated" with guaifenesin. Scientists have recently found that guaifenesin can cause urolithiasis (stones in the urinary system) if taken in excess (2). However, this appears to be related to the practice of drinking large amounts of guaifenesin-containing cough syrups to get high (intoxicated). Oh yeah, last but certainly not least, guaifenesin has never been tested in animals for "carcinogenicity, tumorigenicity, or mutagenicity" (1-BK). Thanks, Big Brother (Not!). |
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This is a great reference book!
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Interference With Lab TestsGuaifenesin can falsely elevate the results of laboratory tests for vanillylmandelic acid (VMA), which is the main urinary metabolite of catecholamines (adrenaline and noradrenaline). In addition, it is well known that guaifenesin can cause false positive results in tests for the serotonin metabolite, 5-hydroxyindoleacetic acid (5-HIAA) (3-NA, 4-BK). You should stop taking guaifenesin 48 hours before giving urine for either of these tests (1-BK). By the way, aspirin also interferes with VMA and 5-HIAA tests (4-BK). Ephedrine and caffeine cause increased values in 5-HIAA tests. Foods that are high in serotonin (avocados, bananas, eggplant, pineapples, plums, and tomatoes) can also cause false positives in 5-HIAA tests. An awful lot of foods and even artifical coloring and flavoring can cause false positives on a VMA test (4-BK). |
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1-BK.) Harrison's Principles of Internal Medicine (CD version with the complete USP-DI.) 2.) Pickens, CL, Milliron, AR, Fussner, AL, Dversdall, BC, Langenstroer, P, Ferguson, S, Fu, X, Schmitz, FJ, and Poole, EC "Abuse of guaifenesin-containing medications generates an excess of a carboxylate salt of beta-(2-methoxyphenoxy)-lactic acid, a guaifenesin metabolite, and results in urolithiasis." Urology 1999 Jul, Vol 54 (1), Pg 23-7, PMID: 10414721. 3-NA.) Pedersen, AT, Batsakis, JG, Vanselow, NA, and McLean, JA "False-positive tests for urinary 5-hydroxyindoleacetic acid. Error in laboratory determinations caused by glyceryl guaiacolate." JAMA 1970 Feb 16, Vol 211 (7), Pg 1184-6, PMID: 5466975. 4-BK.) Fischbach, F "A Manual of Laboratory Diagnostic Tests." J. B. Lippincott Company. 5.) Pade, V, Aluri, J, Manning, L, and Stavchansky, S "Bioavailability of pseudoephedrine from controlled release formulations in the presence of guaifenesin in human volunteers." Biopharm Drug Dispos 1995 Jul, Vol 16 (5), Pg 381-91, PMID: 8527687 6.) Harrison, LI, Chang, SF, Welscher, TM, and Ober, RE "Comparative absorption of theophylline from theophylline-guaifenesin tablets and liquid and from a reference theophylline liquid." Clin Ther 1981, Vol 4 (1), Pg 18-23, PMID: 7273065. 7.) Demirbas, S, Reyderman, L, and Stavchansky, S "Bioavailability of dextromethorphan (as dextrorphan) from sustained release formulations in the presence of guaifenesin in human volunteers." Biopharm Drug Dispos 1998 Nov, Vol 19 (8), Pg 541-5, PMID: 9840216. 8.) Straughn, AB, Wood, GC, Raghow, G, and Meyer, MC "Bioavailability of dyphylline and dyphylline-guaifenesin tablets in humans." J Pharm Sci 1985 Mar, Vol 74 (3), Pg 335-7, PMID: 4009445. 9-BK.) Stedman's Electronic Medical Dictionary (CD Version). |
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