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<p class="ltrs-br-ltr-br-title"><span class="bold">Abuse of Combinations of Gabapentin and Quetiapine</span></p>
<p class="ltrs-br-ltr-br-body-text"><span class="semibold">To the Editor:</span> Medications may be misused, particularly if they produce sedative or anxiolytic effects. We describe misuse of combinations of gabapentin and quetiapine.</p>
<p class="ltrs-br-ltr-br-body-text"> </p>
<p class="ltrs-br-ltr-br-body-text"><span class="semibold-ital">Case report.</span> A 42-year-old man was admitted to a treatment program after his second arrest for driving under the influence of an unknown substance. He had used marijuana and cocaine but stopped after obtaining employment requiring drug testing. Afterward, he had negative drug screens but sometimes appeared “stoned.” He had prescriptions for quetiapine and gabapentin and misused these 2 medications together to replace the drugs he had taken. Taking up to 5 tablets of gabapentin 300 mg with 3 to 4 tablets of quetiapine 200 mg simultaneously produced a sensation of sedation and euphoria.</p>
<p class="ltrs-br-ltr-br-body-text">His girlfriend was prescribed and also misused gabapentin with quetiapine when she could not afford cocaine, taking 3 to 4 tablets of gabapentin 300 mg with 2 to 3 tablets of quetiapine 200 mg, sometimes with beer. She described similar, although weaker, effects. The couple was acquainted with 3 others who misused the same combination by taking 400–800 mg of quetiapine with 900–1,800 mg of gabapentin. Prescriptions were reportedly obtained by fabrication or exaggeration of symptoms. Tablets were sometimes sold or traded for illicit drugs.</p>
<p class="ltrs-br-ltr-br-body-text"> </p>
<p class="ltrs-br-ltr-br-body-text">Evidence exists for abuse of both gabapentin and quetiapine. Both have been removed from several prison formularies because of abuse by inmates. A woman substituted gabapentin 600–1,500 mg daily for cocaine.<span class="htm-cite"><a href="#ref1">1</a></span> Florida inmates admitted snorting gabapentin powder for effects reminiscent of cocaine.<span class="htm-cite"><a href="#ref2">2</a></span> Benzodiazepine-like withdrawal and dependence have been described.<span class="htm-cite"><a href="#ref3">3</a>,<a href="#ref4">4</a></span> Gabapentin has been misused to potentiate the effect of methadone.<span class="htm-cite"><a href="#ref5">5</a></span> About 20 cases of gabapentin addiction have been described in Europe.<span class="htm-cite"><a href="#ref6">6</a></span> There are several reports of oral quetiapine abuse (800–1,200 mg at a time) for sedating and anxiolytic effects.<span class="htm-cite"><a href="#ref7">7</a></span> Quetiapine powder is sometimes snorted intranasally<span class="htm-cite"><a href="#ref8">8</a>;</span> intravenous abuse has also occurred.<span class="htm-cite"><a href="#ref9">9</a></span> Drug-seeking behavior, compulsive use, diversion, dependence, and withdrawal have been described.<span class="htm-cite"><a href="#ref10">10</a>,<a href="#ref11">11</a></span> Quetiapine is sometimes called “quell” or “baby heroin” by inmates.</p>
<p class="ltrs-br-ltr-br-body-text">Gabapentin inhibits voltage-gated calcium channels and entails an increase in γ-aminobutyric acid neurotransmission, as well as modulation of excitatory amino acids at <span class="italic">N</span>-methyl-<span class="smallcaps">d</span>-aspartate receptor sites.<span class="htm-cite"><a href="#ref4">4</a></span> Quetiapine acts as an antagonist at serotonin 5-HT<span class="subscript">1A</span> and 5-HT<span class="subscript">2A</span>, dopamine D<span class="subscript">1</span> and D<span class="subscript">2</span>, histamine H<span class="subscript">1</span>, and adrenergic α<span class="subscript">1</span> and α<span class="subscript">2</span> receptors.<span class="htm-cite"><a href="#ref7">7</a></span> With the 2 drugs combined, many neuroreceptors are affected, and effects at high doses could be significant. Toxicity may exist for patients taking large amounts of gabapentin and/or quetiapine. Clinicians should exercise vigilance when using either to treat patients who use alcohol or illicit drugs, particularly if gabapentin and quetiapine are prescribed concomitantly.</p>
<p class="ltrs-br-ltr-br-references-head"><span class="smallcaps">References</span></p>
<p class="references-references-text-1-9"><a name="ref1"></a>1. Markowitz JS, Finkenbine R, Myrick H, et al. Gabapentin abuse in a cocaine user: implications for treatment? <span class="italic">J Clin Psychopharmacol</span>. 1997;17(5):423–424. <span class="pubmed-crossref"><a href="
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9315994&dopt=Abstract">PubMed</a> <a href="
http://dx.doi.org/10.1097/00004714-199710000-00012">doi:10.1097/00004714-199710000-00012</a></span></p>
<p class="references-references-text-1-9"><a name="ref2"></a>2. Reccoppa L, Malcolm R, Ware M. Gabapentin abuse in inmates with prior history of cocaine dependence. <span class="italic">Am J Addict</span>. 2004;13(3):321–323. <span class="pubmed-crossref"><a href="
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15370954&dopt=Abstract">PubMed</a> <a href="
http://dx.doi.org/10.1080/10550490490460300">doi:10.1080/10550490490460300</a></span></p>
<p class="references-references-text-1-9"><a name="ref3"></a>3. Hellwig TR, Hammerquist R, Termaat J. Withdrawal symptoms after gabapentin discontinuation. <span class="italic">Am J Health Syst Pharm</span>. 2010;67(11):910–912. <span class="pubmed-crossref"><a href="
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http://dx.doi.org/10.2146/ajhp090313">doi:10.2146/ajhp090313</a></span></p>
<p class="references-references-text-1-9"><a name="ref4"></a>4. Kruszewski SP, Paczynski RP, Kahn DA. Gabapentin-induced delirium and dependence. <span class="italic">J Psychiatr Pract</span>. 2009;15(4):314–319. <span class="pubmed-crossref"><a href="
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=19625887&dopt=Abstract">PubMed</a> <a href="
http://dx.doi.org/10.1097/01.pra.0000358318.73684.df">doi:10.1097/01.pra.0000358318.73684.df</a></span></p>
<p class="references-references-text-1-9"><a name="ref5"></a>5. Baird CR, Fox P, Colvin LA. Gabapentenoid abuse in order to potentiate the effect of methadone: a survey among substance misusers. <span class="italic">Eur Addict Res</span>. 2013;20(3):115–118. <span class="pubmed-crossref"><a href="
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=24192603&dopt=Abstract">PubMed</a> <a href="
http://dx.doi.org/10.1159/000355268">doi:10.1159/000355268</a></span></p>
<p class="references-references-text-1-9"><a name="ref6"></a>6. Gabapentin and pregabalin: abuse and addiction. <span class="italic">Prescrire Int</span>. 2012;21(128):152–154. <span class="pubmed-crossref"><a href="
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<p class="references-references-text-1-9"><a name="ref7"></a>7. Reeves RR, Brister JC. Additional evidence of the abuse potential of quetiapine. <span class="italic">South Med J</span>. 2007;100(8):834–836. <span class="pubmed-crossref"><a href="
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http://dx.doi.org/10.1097/SMJ.0b013e3180f62d53">doi:10.1097/SMJ.0b013e3180f62d53</a></span></p>
<p class="references-references-text-1-9"><a name="ref8"></a>8. Pierre JM, Shnayder I, Wirshing DA, et al. Intranasal quetiapine abuse. <span class="italic">Am J Psychiatry</span>. 2004;161(9):1718. <span class="pubmed-crossref"><a href="
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15337673&dopt=Abstract">PubMed</a> <a href="
http://dx.doi.org/10.1176/appi.ajp.161.9.1718">doi:10.1176/appi.ajp.161.9.1718</a></span></p>
<p class="references-references-text-1-9"><a name="ref9"></a>9. Hussain MZ, Waheed W, Hussain S. Intravenous quetiapine abuse. <span class="italic">Am J Psychiatry</span>. 2005;162(9):1755–1756. <span class="pubmed-crossref"><a href="
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=16135642&dopt=Abstract">PubMed</a> <a href="
http://dx.doi.org/10.1176/appi.ajp.162.9.1755-a">doi:10.1176/appi.ajp.162.9.1755-a</a></span></p>
<p class="references-references-text-10-99"><a name="ref10"></a>10. Murphy D, Bailey K, Stone M, et al. Addictive potential of quetiapine. <span class="italic">Am J Psychiatry</span>. 2008;165(7):918. <span class="pubmed-crossref"><a href="
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=18593794&dopt=Abstract">PubMed</a> <a href="
http://dx.doi.org/10.1176/appi.ajp.2008.08020277">doi:10.1176/appi.ajp.2008.08020277</a></span></p>
<p class="references-references-text-10-99"><a name="ref11"></a>11. Yargic I, Caferov C. Quetiapine dependence and withdrawal: a case report. <span class="italic">Subst Abus</span>. 2011;32(3):168–169. <span class="pubmed-crossref"><a href="
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=21660879&dopt=Abstract">PubMed</a> <a href="
http://dx.doi.org/10.1080/08897077.2011.558448">doi:10.1080/08897077.2011.558448</a></span></p>
<p class="ltrs-br-ltr-br-author"><span class="bold">Roy R. Reeves, DO, PhD</span></p>
<p class="ltrs-br-ltr-br-author"><a href="
mailto:roy.reeves@va.gov">
roy.reeves@va.gov</a></p>
<p class="ltrs-br-ltr-br-author"><span class="bold">Randy S. Burke, PhD</span></p>
<p class="ltrs-br-ltr-br-endmatter-fieldnotes"><span class="semibold-ital">Author affiliations:</span> Mental Health Service, G.V. (Sonny) Montgomery VA Medical Center; and Department of Psychiatry, University of Mississippi School of Medicine, Jackson, Mississippi.</p>
<p class="ltrs-br-ltr-br-endmatter-fieldnotes"><span class="semibold-ital">Potential conflicts of interest:</span> None reported.</p>
<p class="ltrs-br-ltr-br-endmatter-fieldnotes"><span class="semibold-ital">Funding/support:</span> None reported.</p>
<p class="ltrs-br-ltr-br-endmatter-fieldnotes"><span class="semibold-ital">Published online:</span> September 11, 2014.</p>
<p class="ltrs-br-ltr-br-copyright-doi"><span class="italic">Prim Care Companion CNS Disord 2014;16(5):</span><span class="doi">doi:10.4088/PCC.14l01660</span></p>
<p class="ltrs-br-ltr-br-copyright-doi"><span class="italic">© Copyright 2014 Physicians Postgraduate Press, Inc.</span></p>
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