Acetaminophen and NSAID Toxicity
Novel and Emerging Therapies
One approach to avoiding gastrointestinal toxicity of NSAIDs is to pair them with fixed doses of gastroprotective agents in single-tablet formulations. For example, Arthrotec®, a combination product of diclofenac and misoprostol, is approved for use in osteoarthritis or rheumatoid arthritis patients at high risk of gastrointestinal disorders. A single-tablet combination of naproxen and esomeprazole is available by prescription under the brand name Vimovo®, and HZT-501 (a combination product of ibuprofen and famotidine) is being developed under the brand name Duexa® (Laine 2012; Conaghan 2012). In two multicenter studies of over 1,500 patients requiring NSAID therapy, HZT-501 demonstrated a ~55% reduction in the risk of ulcer (determined by endoscopy) compared to ibuprofen alone over 24 weeks (Laine 2012). Single tablet preparations may also help overcome poor compliance to prescription NSAID/gastroprotectant regimens (reported at only 68% in one survey) (Goldstein 2006).
Topical NSAIDs, unlike oral NSAIDs, deliver the drug directly to the target tissue, resulting in significantly lower systemic concentrations (<10% of an equivalent oral dose) and reduced gastrointestinal symptoms. Therefore, topical NSAIDs may have advantages over oral NSAIDs in some cases (e.g., osteoarthritis). In the US, only topical diclofenac (solution and gel) has been FDA approved for use in osteoarthritis patients; its efficacy is comparable to oral diclofenac (Roth 2011).