Drug-Induced Vitamin B-12 Deficiency
A guiding principle in geriatrics is to assume that any symptom in an elderly adult is a drug side effect until proven otherwise.
Diabetic patients often experience symptoms of neuropathy, either as pain or loss of feeling in the lower extremities. Many older adults experience cognitive decline especially those with dementia. In both cases Vitamin B-12 deficiency should be ruled out before assuming the symptoms are due to disease progression. If not treated, Vitamin B-12 deficiency can cause pernicious anemia, neuropathy, and cognitive decline.
Metformin is considered a first-line treatment for adult-onset (Type II) diabetes. However, metformin can cause malabsorption of Vitamin B-12. This is thought to be due to a decrease in bile acid secretion resulting in bacterial overgrowth that causes decreased intestinal absorption. Vitamin B-12 levels can be restored by stopping metformin, B-12 supplementation, or administration of doxycycline or calcium.
Vitamin B-12 absorption can also be reduced by drugs that reduce stomach acidity including proton pump inhibitors (PPIs) and histamine receptor antagonists (HRAs). Commonly prescribed PPIs include omeprazole and pantoprazole while the most utilized HRAs are famotidine and ranitidine. Higher doses and longer duration of treatment with these drugs increases the risk for malabsorption of not only Vitamin B-12, but also calcium carbonate, iron, and magnesium.
AlixaRx Clinical Pharmacists routinely evaluate the need for continued treatment, especially with higher doses of PPIs and will make recommendations to optimize therapy. Utilizing the lowest effective dose for the shortest duration will avoid complications such as malabsorption of critical vitamins and minerals.
Nurses and prescribers should consult their AlixaRx Clinical Pharmacist for a change of condition medication review if they suspect patient symptoms may be drug-induced or if they cannot rule out a drug cause.
This article was originally published in our monthly issue of From the Front Lines – a monthly publication that shares best practices and medication-related challenges faced by “front line” staff in long-term care and post-acute (LTCPAC) facilities.
