84 with between-rater reliability testing, and its probability scale has consensual, content, and concurrent validity as well as ease of use [13, 14]. The Naranjo algorithm rates this drug interaction as “probable.” Conclusion Though a paucity of definitive data from controlled studies regarding interactions between HAART medication and antipsychotics exists, CYP450 enzyme disturbances are documented within each drug class. This case demonstrates the immediate and detrimental effects due to the addition of antipsychotic medications to previously altered CYP450 enzyme levels. The CYP450 inhibition of enzymes 3A4 and 2D6 by the combination PI, lopinavir/ritonavir, is likely the major culprit in causing increased free levels of perphenazine and quetiapine. The immediate high level of free drug caused an α-blockade resulting in priapism shortly after ingesting the new antipsychotics. Clinicians should be aware of this rare but potentially serious adverse event. Further investigation is warranted regarding potential interactions between HAART and antipsychotic medications to elucidate potential mecha- nisms of adverse effects. All authors contributed substantially to the Author’s contributions report and its revision. Conflict of interest None. Funding No grants, financial support, or compensation has been provided for this work. References 1. Repetto MJ, Petitto JM (2008) Psychopharmacology in HIV- infected patients. Psychosom Med 70(5):585–592 2. Ferrando SJ, Wapenyi K (2002) Psychopharmacological treatment of patients with HIV and AIDS. Psychiatr Q 73(1):33–49 3. Sikka R, Magauran B, Ulrich A, Shannon M (2005) Bench to bedside: pharmacogenomics, adverse drug interactions, and the cytochrome P450 system. Acad Emerg Med 12(12):1227–1235 4. Sood S, James W, Bailon MJ (2008) Priapism associated with atypical antipsychotic medications: a review. Int Clin Psycho- pharmacol 23(1):9–17 5. Casiano H, Globerman D, Enns MW (2007) Recurrent priapism during treatment with clozapine, quetiapine and haloperidol. J Psychopharmacol 21(8):898–899 Int J Emerg Med (2010) 3:81–84 6. Davol P, Rukstalis D (2005) Priapism associated with routine use of quetiapine: case report and review of the literature. Urology 66 (4):880 7. Harrison G, Dilley JW, Loeb L, Nelson K (2006) Priapism and quetiapine in an HIV-positive male. J Clin Psychopharmacol 26 (1):100–101 8. Pais VM, Ayvazian PJ (2001) Priapism from quetiapine overdose: first report and proposal of mechanism. Urology 58(3):462 9. Prado MJA, Formoso MV (2006) Priapism associated with quetiapine in an elderly patient. Actas Esp Psiquiatr 34(3):209– 210 10. Chan J, Alldredge BK, Baskin LS (1990) Perphenazine-induced priapism. DICP 24(3):246–249 11. Tejera CA, Ramos-Lorenzi JR (1992) Priapism in a patient receiving perphenazine. J Clin Psychopharmacol 12(6):448–449 12. Lacy C, Armstrong L, Goldman M, Lance L (eds) (2008) Lexi- Comp drug database drug information handbook, 17th edn. Lexi-Comp Information Management Service (LIMS), Hudson, pp 15–16, 939–942, 1227, 1332–1335 13. Kelly WN (2008) How can I recognize an adverse drug event? MedscapeCME Pharmacists 14. Naranjo C, Busto U, Sellers EM et al (1981) A method for estimating the probability of adverse drug reactions. Clin Pharmacol Ther 30:239–245 Matthew J. Geraci is a Clinical Pharmacist in the Emergency Department at Baptist Medical Center Downtown in Jacksonville, FL and a Clinical Assistant Professor of Pharmacy Practice with the University of Florida. He completed his postgraduate residency at the Mayo Clinic, Jacksonville, FL. He received his PharmD from the University of Utah and a BS in Physics/Nuclear Engineering from West Point. Stacey L. McCoy is a Clinical Pharmacist in the Emergency Department at Baptist Medical Center Downtown in Jacksonville, FL and a Clinical Assistant Professor of Pharmacy Practice with the University of Florida. She completed her postgraduate residency at St. Joseph’s/Candler Hospital, Savannah, GA. She received her PharmD from Mercer University and a BS/MS from Clark Atlanta University. She is a Board Certified Pharmacotherapy Specialist. Paul M. Crum is a Consulting Urologist at McIver Urological Clinic, Riverside Office, in Jacksonville, FL. He completed his postgraduate residency at the U.S. Naval Hospital in Philadelphia, PA and attended medical school at the University of Pennsylvania. He is a Fellow of the American College of Surgeons, Board Certified in Urology, and member of the Society of Pediatric Urologists. Rajnikant A. Patel is an Attending Physician with the Emergency Resources Group at Baptist Medical Center in Jacksonville, FL. He completed his postgraduate residency at King Edward VII Memorial Hospital in Bombay, India; Albert Dock Hospital in London, UK; and at the University Hospital of Jacksonville in FL. He attended medical school at G.S. Medical College, University of Bombay in India and is a Fellow of the American College of Emergency Physicians.