1. Examining Potential Misuse of Gabapentin Among Patients Admitted to an Inpatient Behavioral Health Unit
Samuel Kubas a, Pharm.D. Candidate 2018; Lucas Shumaker a, Pharm.D. Candidate 2017 John R. Tomko a, b, Pharm.D., BCPP; Konasale Prasad b, MD
a Duquesne University Mylan School of Pharmacy
b UPMC Mercy Hospital, Pittsburgh PA
BACKGROUND
Gabapentin is an FDA approved medication indicated for either the adjunctive treatment of partial seizures or post-herpetic neuralgia.1 It has been studied for many “off-label” uses with varying degrees of success.2 Its use in such conditions as diabetic peripheral neuropathy, fibromyalgia, and alcoholism maintenance contains moderate evidence. It has also been utilized in such conditions as migraine prophylaxis, complex regional pain syndrome, hot flashes, bipolar disorder, anxiety, and restless leg syndrome with less success.3
There have been surveys that estimate physician knowledge of the approved use of gabapentin as well as the level of evidence for off label uses.4 It was found that many physicians lacked knowledge about FDA approved uses and that much of the information that they possessed was anecdotally received from colleagues. Therefore, many clinical decisions made on the prescribing of gabapentin is based upon anecdotal personal testimony of efficacy.5 A reason for this misinformation may be due to the illegal practice of promotion for off-label uses that occurred during the early part of this century.6, 7, 8, 9 Therefore, this offers one potential explanation for the widespread “off-label” prescription of the agent.
Recently, gabapentin has been reported as a drug of abuse.10, 11 It has been abused as a euphoric agent, similar to the physiological effects of marijuana and alcohol.1 There are also reports of the drug being used in conjunction with other drugs of abuse and even with opioid replacement treatments in order to intensify the desired effect.12, 13 Furthermore, since gabapentin is not a controlled substance, it may also be easier to obtain than controlled substances or even illicit drugs of abuse.
OBJECTIVES
The purpose of this study is to determine the extent of gabapentin misuse prior to admission to a hospital behavioral health unit. Secondary goals are to determine the rate at which gabapentin is being used by substance misusers, and to determine if the use of gabapentin correlates with the need for medical detoxification upon admission. A further goal is to determine the extent to which gabapentin is being used off-label, and to determine if a correlation exists between this off-label use and either the need for medical detoxification or a patient history of substance misuse disorder. The study was approved by both the hospital and university Institutional Review Board.
DECLARATIONS
The authors declare no conflict of interest in the design, analysis, or presentation of this work.
Author Contact:
Samuel Kubas, PharmD candidate 2018;
Lucas Shumaker, PharmD candidate 2017;
John R. Tomko, Pharm.D., BCPP;
Konasale Prasad, MD;
METHODS
Study design is a cross-sectional study of all subjects prescribed gabapentin on admission to a behavioral health unit. Subject demographic data collected included age, gender, race, BUN, creatinine, glomerular filtration rate, substance use disorder status, and urine drug screen (UDS) results. Additional information regarding psychiatric diagnosis, medical diagnoses, positive agents on UDS, and the need for medical detoxification protocols on admission (alcohol/benzodiazepines, opiates, or both) was recorded. The dose of gabapentin prescribed just prior to admission was also collected. Lastly, the reasons for gabapentin administration were ascertained from the admission medical record in terms of the subjects’ specific diagnoses. It was further determined if the use was for an FDA approved indication or for off-label use. Data was analyzed using SPSS 22.0 (IBM Corp, Armond, NY).
OUTCOMES
This study will be a minimum of one year in length. Preliminary results have included 290 individuals throughout the first three months of the study that were admitted to the behavioral health unit, of which 80 (27.6%) were identified as currently taking gabapentin. Of the 80 identified subjects, 4 (5%) had an FDA indicated diagnosis of partial seizure disorder. Two of these subjects were on gabapentin for partial seizures and did not have a positive UDS. Of the 76 subjects using gabapentin for an off label indication, 11 (14.1%) were using it for an undetermined reason. Moreover, 74/80 (92.5%) were current substance misusers or have a past SUD history. Of these substance misusers, 71 (96%) tested positive for an illicit substance or substances upon admission. Notably, 49 (66.2%) tested positive for polysubstance abuse (61.3% of the total sample). Of the 71 positive screenings, 65 subjects (91.5%) required detoxification protocol(s), which was 81.3% of the total sample. Fifteen subjects (18.8%) were on maintenance therapy for substance misuse. Five were on methadone and 10 were on buprenorphine, which is 6.3% and 12.5% of the total sample, respectively. The overall daily dose for patients in the sample was mg +/ This dose was 1650mg +/ for those without substance misuse disorder and mg +/ for those with a history of or current substance misuse. The total daily dose in those subjects receiving opioid replacement therapy was higher; 2290mg +/ for those on buprenorphine maintenance and 2380mg +/ in those on methadone. There was also a highly significant correlation (Pearson correlation 0.593, p≤0.01) between a history of substance misuse and the need for detoxification in subjects taking gabapentin. There was also a moderate correlation between substance misuse history and the off-label use of gabapentin (Pearson correlation .258, p≤0.05). A summary of subject demographics is included in Table 1.
DISCUSSION
The study will be completed no sooner than December Full results and analysis will be published upon completion of the study. The findings at the 3 month mark suggest that amongst patients treated in a behavioral health unit and prescribed gabapentin prior to admission, there is a high likelihood that these same patients will require medical detoxification from drugs of abuse. Additionally, those being treated with methadone or buprenorphine maintenance presented with higher prescribed doses than those without this treatment.
Table 1. Subject demographics *
REFERENCES