Antacid attenuates the laxative action of magnesia in cancer patients receiving opioid analgesic. (30th June 2016)

• Record Type: Journal Article
• Authors: Ibuka, Hirokazu; Ishihara, Masashi; Suzuki, Akio; Kagaya, Hajime; Shimizu, Masahito; Kinosada, Yasutomi; Itoh, Yoshinori
• Is Part Of: Journal of pharmacy and pharmacology. Volume 68:Number 9(2016:Sep.)
• Page Start: 1214
• Page End: 1221
• Publication Date: 2016-06-30
• Subjects: antacid -- constipation -- laxative -- magnesia -- opioid analgesic -- pharmacological interaction; Pharmacy -- Periodicals; Pharmacology -- Periodicals; 615.1
• DOI: 10.1111/jphp.12600
• Languages: English
• ISSNs: 0022-3573

Abstract

Abstract: Objective: This study was designed to investigate pharmacological interaction between magnesium laxative and antacid in patients receiving opioid analgesic. Methods: Data obtained from a total of 441 eligible patients receiving opioid analgesic for the first time were retrospectively analysed. The incidence of constipation, defined as stool-free interval of 3 days and more within the first week of opioid intake, was compared between patients who took laxative alone and those who received laxative in combination with antacid. Key findings: Laxatives were prescribed in 74% of patients, among them 61% received antacids such as proton pump inhibitor and H2 receptor blocker. Magnesia was the most commonly used laxative (89%). Constipation occurred in 21% and 55% of patients with and without laxatives, respectively. Antacids reversed the laxative action of lower doses (<2000 mg/day) but not higher doses (> 2000 mg/day) of magnesia without affecting the effects of other laxatives. Therefore, it is suggested that both acid-dependent and acid-independent mechanisms may operate in the laxative action of magnesia, in which the former may be involved in the action of lower doses of magnesia. Conclusion: Care should be taken to avoid the unfavourable pharmacological interaction between low doses of magnesia and antacid.