Gabapentin-induced bilateral lower extremity edema in a patient with pervasive developmental disorder and schizoaffective disorder

Abstract

<jats:title>Abstract</jats:title> <jats:p>Gabapentin binds to the alpha-2-delta subunit of presynaptic voltage-gated calcium channels and is used for a wide variety of on- and off-label indications. Gabapentin is dosed at total daily doses ranging from 300 to 3600 mg/d, which is generally divided into 3 doses. Although gabapentin is generally well tolerated, 1 potential reported adverse effect is peripheral edema. However, due to the extensive number of etiologies of peripheral edema, medication causes may be overlooked on an inpatient psychiatric unit. This is a case of delayed identification of a probable adverse drug reaction to gabapentin (Naranjo score of 5) consisting of painful, 4+ pitting bilateral edema and a clear dose relationship in a patient with pervasive developmental disorder and schizoaffective disorder.</jats:p>

Drug‐induced peripheral oedema: An aetiology‐based review

“…water retention through reactive RAAS stimulationGabapentinoids:94,95 Gabapentin, pregabalin -preferential precapillary arteriolar vasodilatation and inhibition of the myogenic response through Cav1.2 inhibition31,[96][97][98] …”

Case report: Escitalopram-associated lower limb edema

“…In a pooled analysis from clinical trials, the incidence increased from 1.4% to 7.5% with doses of 1800 mg/day and up to 12.3% at 3600 mg/day. However, there are cases of edema developing at doses lower than 1800 mg/day, indicating that it might not always be dose-related (7). It's also important to note that while CCBassociated edema is a frequent issue leading to the use of diuretics, this type of edema is not caused by fluid overload, and using diuretics can pose risks, especially in older adults (6).…”

Which older adults are at highest risk of prescribing cascades? A national study of the gabapentinoid–loop diuretic cascade

“…Among new users of gabapentinoids, we limited the cohort to those individuals who newly started a LD within 6 months before or after the index date. We adopted this observation window for several reasons: (1) given that most-but not all-gabapentinoidinduced edema occurs in the first few months after prescription, LD use beyond this window is less likely to be attributable to gabapentinoid-induced edema 25 ; (2) to allow for detection of gabapentinoid-induced edema over time given available evidence which suggests that gabapentinoid-induced edema is more likely with higher doses and following dose increases 11,25,26 ; and (3) balancing between the various observation windows (90, 180, and 360 days) adopted in a prior PSSA study of this prescribing cascade. 11 To improve measurement of prescribing within the VA's integrated health system, we excluded older adults who were enrolled in Medicare Part D or Medicare Advantage (given that utilization data may not be complete for these individuals, 27 and in line with our prior studies 28,29 ) from 1 year prior to and 6 months after the index date.…”