H2-Blockers in the Elderly

Background

H2-blockers have had a reputation for causing CNS side effects in the elderly for a long time. They may all have some degree of anticholinergic activity, but data from studies associating delirium with H2-blockers are inconsistent.^1,2 However, there’s a wealth of case studies reporting delirium with cimetidine, and cimetidine has been listed in the Beers criteria for a number of years. Now the Beers list has been revised to include all H2-blockers as being potentially inappropriate for certain elderly patients. This document reviews caveats and considerations associated with use of H2-blockers in the elderly.

When To Avoid H2-Blockers In The Elderly

The most recent iteration of the Beers list, updated in 2012, includes all H2-blockers instead of just cimetidine.³ However, this doesn’t mean that all H2-blockers should be avoided in all elderly patients. H2-blockers used in patients with delirium or a high risk of delirium (e.g., age >65 years, severe illness, hip fracture),¹ dementia, or cognitive impairment may cause or worsen delirium and worsen cognitive impairment. In these patients specifically, another agent for acid suppression, such as an antacid or a proton pump inhibitor (PPI), should be considered instead of an H2-blocker.³

In addition to thinking twice before using H2-blockers in the patients mentioned above, it is important to consider that H2-blockers might be contributors when elderly patients have acute cognitive decline.

Considerations When Using H2-Blockers In The Elderly

Many elderly patients have reduced renal function (i.e., creatinine clearance less than 50 mL/min). H2-blockers are renally eliminated and their dosing should be reduced for CrCl less than 50 mL/min (less than 30 mL/min for cimetidine).^4-7,11-14 OTC doses are lower than prescription doses and are generally appropriate for most elderly patients.

In the elderly, it may be even more important than usual to periodically monitor and re-evaluate the need for acid suppression. For patients with conditions that require chronic therapy (e.g., pathological hypersecretory conditions, high risk of GI bleeding with an NSAID), a PPI may be considered.³ However, PPIs aren’t risk-free either. Keep in mind the potential problems that have been associated with PPIs such as an increased risk of C. difficile-associated diarrhea, pneumonia, bone fractures, vitamin B12 deficiency, and low blood levels of magnesium. Be sure to adjust the dose of the PPI appropriately based on indication.

Drugs with anticholinergic activity can generally cause delirium, cognitive dysfunction, and other adverse effects in the elderly. Based on in vitro data, cimetidine and ranitidine both appear to have medium to high anticholinergic activity and famotidine and nizatidine both appear to have low anticholinergic activity. However, when it comes to using drugs with any anticholinergic activity in the elderly, the focus isn’t always on the anticholinergic activity of a single drug. Individuals who take multiple drugs with low levels of anticholinergic activity can also have an increased risk of adverse effects. This concept is referred to as anticholinergic burden or anticholinergic load. Even small increases in anticholinergic burden or load can increase morbidity and mortality in older individuals.^8-10 Be sure to consider H2-blockers as part of a patient’s anticholinergic burden.

Conclusion

Avoid using H2-blockers in elderly patients with impaired cognition [Evidence level C; consensus].³ In other elderly patients, be sure to reduce doses appropriately for renal function, reassess the need for acid suppression periodically, and assess anticholinergic burden when using H2-blockers.

Levels of Evidence

In accordance with the trend towards Evidence-Based Medicine, we are citing the LEVEL OF EVIDENCE for the statements we publish.

Adapted from Siwek J, et al. How to write an evidence-based clinical review article. Am Fam Physician 2002;65:251-8.

Project Leader in preparation of this PL Detail-Document: Stacy A. Hester, R.Ph., BCPS, Assistant Editor

References

1. Clegg A, Young JB. Which medications to avoid in people at risk of delirium: a systematic review. Age Ageing 2011;40:23-9.
2. PL Detail-Document, Drugs with Anticholinergic Activity. Pharmacist’s Letter/Prescriber’s Letter. December 2011.
3. The American Geriatrics Society 2012 Beers Criteria Update Expert Panel. American Geriatrics Society updated Beers criteria for potentially inappropriate medication use in older adults. J Am Geriatr Soc 2012;60:616-31.
4. Product information for cimetidine. Mylan. Morgantown, WV 26505. September 2005.
5. Product information for famotidine. Merck. Whitehouse Station, NJ 08889. October 2010.
6. Product information for nizatidine. Teva. Sellersville, PA 18960. August 2008.
7. Product information for ranitidine. Sandoz. Princeton, NJ 08540. June 2011.
8. Rudolph JL, Salow MJ, Angelini MC, McGlinchey RE. The anticholinergic risk scale and anticholinergic adverse effects in older persons. Arch Intern Med 2008;168:508-13.
9. Carnahan RM, Lund BC, Perry PJ, et al. The Anticholinergic Drug Scale as a measure of drug-related anticholinergic burden: associations with serum anticholinergic activity. J Clin Pharmacol 2006;46:1481-6.
10. Indianapolis Discovery Network for Dementia. Anticholinergic Burden List (ACB). http://www.indydiscoverynetwork.org/resources/ACB%20Scoring%20List_2011%20NC.pdf. (Accessed June 7, 2012).
11. Product monograph for cimetidine. Mylan. Etobicoke, ON M8Z 2S6. September 2009.
12. Product monograph for Pepcid. Merck Canada. Kirkland, QC H9H 4M7. April 2011.
13. Product monograph for Axid. Pendopharm. Montreal, QC H4P 2T4. January 2012.
14. Product monograph for Zantac. GlaxoSmithKline. Mississauga, ON L5N 6L4. August 2010.

Cite this document as follows: PL Detail-Document, H2-Blockers in the Elderly. Pharmacist’s Letter/Prescriber’s Letter. July 2012.