On physical exam, her blood pressure is 160/91, up from the last visit 6 months when it was 124/72. She claims to have been following her low salt diet and walking at the mall 3 days a week. You can find no other physical or lab cause to explain her increased blood pressure.

What is causing her elevated blood pressure?

Assuming the calibration of the sphygmomanometer is true, the measurement and technique are correct, and there's no other medical condition/cause, maybe the "expensive new pill" for her arthritis is causing the elevation?

NSAIDs have well known toxicities, especially gastrointestinal and renal effects. In an elderly patient, a COX2 agent MAY(?) be a reasonable choice because of a presumed decrease in GI toxicity. Increasing age is a risk factor for GI bleeding. COX2 agents do reduce GI erosions but these reductions don't always translate into a decrease in clinical ulcers or GI bleeds. Recent literature shows that combining COX2 agents with even low dose aspirin (ex. 81mg) may defeat whatever GI protection MAY be gained from the COX2 agent. Aspirin is recommended in patients on COX2 agents who need aspirin for it's anti-platelet effects since COX2 agents have little or no platelet effects. One COX2 study showed an increase in thrombosis in patients on a COX2 agent when compared with traditional NSAIDs. COX2 agents have similar renal effects as traditional NSAIDs.

NSAIDs have long been known to antagonize renal prostaglandins and interfere with diuretic activity of various drugs. NSAIDs can also cause hyperkalemia and acute renal failure (although ARF is relatively rare). In this small non-controlled case report, COX2 agents appear to be no different. An article reporting on three cases in the Journal of Clinical Hypertension (J Clin Hypertens 2000;2:396-8) details three elderly female patients with hypertension. All three were well controlled various antihypertensives only to lose control of the blood pressure when started on a COX2 agent. Blood pressure returned to baseline levels when the COX2 was discontinued.

Providers should be vigilant with their hypertensive patients who are started on traditional NSAIDS or COX2 agents. Also, in an elderly patient on an ACE inhibitor AND a NSAID, compromised renal function and decreased intraglomerular pressure and filtration may be significantly compromised.