I appreciate the fantastic guest post from Amanuel Tseggai, Pharm.D., BCPS!
There are plenty of clinical considerations when it comes to gabapentin. Here’s a scenario of using gabapentin in chronic kidney disease.
A 42 year old African American man with a history of coronary artery disease and decompensated heart failure s/p heart transplant and chronic kidney disease presented to a hospital on 9/29/16 complaining of shortness of breath, dyspnea upon exertion and LE edema. On admission his rapamycin level was undetectable which concerned the primary care givers of possible rejection.
Two days after his admission, a family member noticed some behavioral changes, including confusion, altered mental status which was confirmed by a nurse who was caring for him at the time.
Drug in question: Gabapentin 300mg q8h
Laboratory:
| Date: BUN SRCR CRCL |
| 9/29 45 3.83 28ml/min |
| 9/30 58 5.32 20 |
| 10/1 62 6.38 17 |
| 10/1 71 7.19 15 |
Action:
Gabapentin was discontinued and patient received hemodialysis the following day after transferring him to ccu.
According to progress note from nephrologist, patient showed some improvement in mental status after receiving dialysis, with some confusion accompanied with tachycardia. Uremia was suspected as the major contributing factor to his altered mental status, encephalopathy.
Discussion:
Clinical manifestations of uremic encephalopathy include fatigue, muscle weakness, malaise, headache, restless legs, asterixis, polyneuritis, mental status changes, muscle cramps, seizures, stupor, and coma.(ref: http://emedicine.medscape.com/article/245296-clinical)
Gabapentin has also been linked to causing behavioral changes such as confusion and CNS depression including somnolence and dizziness, which is more prominent in patients with renal impairment. (Lexicomp 2016).
Take home message:
Pharmacists who help manage patient’s regimen both in an institution and outpatient basis should be mindful of and closely monitor laboratory parameters that sway on how we treat patients one way or the other. Majority drugs, including Gabapentin, are eliminated by the kidneys and will accumulate to a toxic level in renally compromised patients as in this case.
Per Lexicomp, Gabapentin’s recommended dose in patients with renal impairment is as follows:
CrCl >15 to 29 mL/minute: 200 to 700 mg once daily
CrCl 15 mL/minute: 100 to 300 mg once daily
CrCl <15 mL/minute: Reduce daily dose in proportion to creatinine clearance based on dose for creatinine clearance of 15 mL/minute (eg, reduce dose by one-half [range: 50 to 150 mg/day] for CrCl 7.5 mL/minute)
ESRD requiring hemodialysis: Dose based on CrCl plus a single supplemental dose of 125 to 350 mg (given after each 4 hours of hemodialysis
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