Adverse effect of topical methylsalicylate ointment on warfarin anticoagulation: an unrecognized potential hazard

Yip, Adrian Y S; Chow, Wing‐Hing; Tai, Yau-Ting; Cheung, King‐Loong

doi:10.1136/pgmj.66.775.367

Cited by 47 publications

(20 citation statements)

References 5 publications

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“…This supports the previous findings that physiotherapists lack knowledge on topical medications, which have similar risks as oral medications [9]. This is corroborated by the findings that the use of topical methyl salicylate ointments in cardiac disease patients receiving anticoagulation therapy could portend: a risk of bleeding manifestation, bruises in the skin, and gastrointestinal bleeding [23].…”

Section: Discussionsupporting

confidence: 91%

An evaluation of the knowledge level of Nigerian physiotherapists on topical pharmacotherapy

Onigbinde

Olaogun

Iroghue

2012

Hong Kong Physiotherapy Journal

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Conventional treatment for some diseases involves a combination of pharmacotherapy and physiotherapy. Most of Nigeria's training schools have introduced the course of pharmacology in their training curriculum but its effect is still unknown. There appears to be inadequate research on physiotherapists' knowledge of medications in Nigeria. The primary objectives of this study were to determine the knowledge of Nigerian physiotherapists regarding topical pharmacotherapy and to determine the association between knowledge of active ingredients and age, clinical experience, qualification, and work setting. A total of 135 practising physiotherapists participated in the cross-sectional survey study. A selfadministered questionnaire was used for this study. Descriptive statistics and Pearson chi-square were used to analyse the data obtained. Only 55 respondents (40.7%) reported that they recently updated their knowledge on topical medications; however, this contradicted the finding that only one participant (0.7%) had very good knowledge while 57 respondents (42.2%) have poor knowledge of the active ingredients in the topical medications listed in this study. Also, 105 respondents (77.8%) indicated their awareness that physiotherapists can recommend topical drugs. The results of this study revealed that some of the sampled physiotherapists have poor knowledge about adverse reactions, contraindications, risks, and mechanisms of action of the listed drugs, and how non-steroidal anti-inflammatory drugs relieve pain. However, results also showed that the respondents had good knowledge (mean score of 2.46 AE 1.03 out of the maximum of score of 3 allotted) of the conditions in which topical medications are indicated, although they have a poor knowledge of the common adverse reactions of topical medications applicable in physiotherapy (mean score of 1.44 AE 1.16 out of the maximum score of 4). A total of 111 respondents (80.7%) could not explain how topical non-steroidal anti-inflammatory drugs relieve pain. The results also showed that there was a significant association between years of clinical experience and scores obtained for knowledge about active ingredients (c 2 Z 347.903, p < 0.03). The study concluded that most Nigerian physiotherapists have poor knowledge of

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Section: Discussionsupporting

confidence: 91%

An evaluation of the knowledge level of Nigerian physiotherapists on topical pharmacotherapy

Onigbinde

Olaogun

Iroghue

2012

Hong Kong Physiotherapy Journal

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“…Topical methyl salicylate may potentiate the anticoagulant effect of warfarin 86,169 , probably by inhibition of warfarin metabolism.…”

Section: Drugs Causing Inhibition Of Metabolismmentioning

confidence: 99%

“…A combination of paracetamol and codeine has enhanced warfarin activity 163 . The commonly used analgesic (propoxyphene plus paracetamol) may potentiate the effect of warfarin 161,166,167,168 .Topical methyl salicylate may potentiate the anticoagulant effect of warfarin 86,169 , probably by inhibition of warfarin metabolism.Metronidazole and co-trimoxazole (combination of sulfamethoxazole and trimethoprim) strereoselectively inhibit the metabolism of S-warfarin 170 . The interaction with co-trimoxazole is generally attributed to the sulfamethoxazole moiety and there are isolated reports suggesting that the activity of warfarin may be enhanced by other sulphonamides including sulphafurazole 171 , sulphamethizole 172 and suphaphenazole 173 .…”

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confidence: 99%

Interactions of Warfarin

Rehulková¹

2001

Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub

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In this article, the author reviews and updates the basis of interactions with warfarin, illustrated with appropriate examples. The interactions with drugs, medicinal herbs and foods are summarised. 28Cholestyramine binds vitamin K in the gut, thus preventing its absorption 18 . It also decreases the absorption and may interrupt the enterohepatic recirculation of warfarin, resulting in a reduced anticoagulant effect 19,20 .Colestipol does not affect the absorption of warfarin. When colestipol is administered with warfarin, no depressant effects on blood levels are seen 21 . Drugs affecting receptor sensitivityEstrogens increase the synthesis of various clotting factors and may thus reduce the effect of anticoagulants 22, 23 . Oral contraceptives increase clotting factor concentrations and inhibit warfarin metabolism. The net effect depends on balance between these factors. Oral contraceptives are generally contraindicated in most patients taking warfarin since they are trombogenic 1, 24 .Steroids with anabolic or androgenic properties, such as oxymetholone 25, 26, 27 , stanozolol 28, 29 and danazol 30, 31, 32 , may potentiate the action of warfarin allegedly by reducing clotting factor synthesis. The 17-alpha-alkylated steroids appear to be more likely to induce this reaction than the non-substituted steroids 25, 26, 27, 33 . However, there has been a report of topically applied testosterone, which does not have 17-alpha-alkyl substituent, enhancing warfarin 34 .Diuretics may antagonise the action of warfarin by two pharmacodynamic mechanisms 18 : (a) patients in cardiac failure have impaired clotting factor synthesis due to hepatic congestion -correction of this state leads to increased clotting factor synthesis; (b) diuretics also reduce the plasma volume producing an increased concentration of clotting factors which may alter the anticoagulant effect of warfarin 35 . Chlorthalidone 36 and spironolactone 35 have both been associated with a reduction of warfarin activity probably as a consequence of diuresis concentrating the circulating clotting factors. Bumetanide, furosemide and thiazides appear to have no effect on warfarin 23 .Certain cephalosporines, such as cefotetan, cefamandole, cefoperazone, or moxalactam may cause marked hypoprothrombinemia and/or prolonged bleeding time at concurrent use with warfarin 38, 39, 40, 41 . The main mechanism of interaction consists in decreasing synthesis of vitamin K-dependent clotting factors.Clofibrate may potentiate warfarin action, probably by altering receptor sensitivity 23, 37 . Although clofibrate displaces warfarin from albumin binding sites this does not appear to be a principal mechanism of the interaction 42 .Drugs altering thyroid function may affect anticoagulant control, since rates of synthesis and degradation of clotting factors are dependent on thyroid function 7 . Thyroid compounds do enhance the activity of oral anticoagulants by increased metabolism of clotting factors 12 . Dextrothyroxine increases the anticoagulant effect of warfarin ...

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“…The major sites of bleeding are the alimentary tract and soft tissues, but death due to warfarin induced bleeding is most commonly due to intracerebral haemorrhage. Adverse interactions of warfarin with other drugs are a well recognised cause of serious bleeding complications (Yip et al 1990).…”

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confidence: 99%

Adverse Interaction between Warfarin and Indomethacin

et al. 1994

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A 57-year-old man developed spontaneous skin bruising and haematuria during combined therapy with warfarin and indomethacin. Due to the potential effects of nonsteroidal anti-inflammatory drugs (NSAIDs) on the anticoagulant action of warfarin and platelet function, patients receiving both warfarin and NSAIDs should have their prothrombin time monitored very closely. Also, the risk of gastrointestinal haemorrhage with any NSAIDs must always be remembered.

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Adverse effect of topical methylsalicylate ointment on warfarin anticoagulation: an unrecognized potential hazard

Cited by 47 publications

References 5 publications

An evaluation of the knowledge level of Nigerian physiotherapists on topical pharmacotherapy

An evaluation of the knowledge level of Nigerian physiotherapists on topical pharmacotherapy

Interactions of Warfarin

Adverse Interaction between Warfarin and Indomethacin

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