Effect of Topical Application of Nigella Sativa Oil and Oral Acetaminophen on Pain in Elderly with Knee Osteoarthritis: A Crossover Clinical Trial

BACKGROUND Limited evidence supports Nigella sativa's role as an effective complementary and alternative medicine and the anti-inflammatory effects of Nigella sativa on patients with allergic rhinitis. OBJECTIVE The aim of this study was to investigate the effect of topical application of Nigella sativa oil and oral acetaminophen on pain in the elderly with knee osteoarthritis residing in a parents' home in Sabzevar. METHODS This study is done as a crossover clinical trial. After obtaining written consent of elderly patients with osteoarthritis of the knee, they were randomly divided into two groups. In step 1, in group 1, 1 cc of Nigella sativa oil was applied on the knee joint every 8 hours for 3 weeks; for the second group, every 8 hours for 3 weeks, patients were given 1 tablet of 325 mg acetaminophen. After a period of 1 month without medication to wash out each group, in step 2, each treatment group received the drug interaction in the same way as above. Pain was determined using a visual scale (VAS) before and after the first and second stages. Treatment response was defined as a decrease in pain scores over 1.5. Data analysis was performed with an R software mixed model. RESULTS This study was done on 40 elderly patients: 18 (45%) men and 22 (55%) women. Their mean year and weight were 75.66±8.9 years and 69.67±14.33 kg, respectively. Study results showed that topical application of Nigella sativa oil and oral acetaminophen reduced pain in elderly with knee osteoarthritis; after using Nigella sativa oil, the reduction of pain was higher (p=0.01). CONCLUSION The results of this study showed that topical application of Nigella sativa oil was effective in reducing pain in patients with knee osteoarthritis; therefore, it is recommended as a safe supplement for these elderly. TRIAL REGISTRATION The trial was registered at TCTR (http://www.clinicaltrials.in.th/) with the ID: TCTR20160125003. FUNDING This study was approved and supported by the Sabzevar University of Medical Sciences.