Pharmacist-Delivered Pharmaceutical Care in a Patient with Advanced HIV Disease Complicated by Acute Gastroenteritis: A Case Report Highlighting How Incomplete Antiretroviral Regimen Documentation Limits Drug-Interaction Assessment

Abstract

Acute gastroenteritis in a person living with HIV who has a history of poor antiretroviral therapy (ART) adherence and unintentional weight loss is a recognised presentation of advanced HIV disease, requiring a package of opportunistic infection screening, ART re-engagement, and careful medication review. Pharmaceutical care in this setting is complicated by polypharmacy across antiretroviral, antimicrobial, antiparasitic and supportive therapies, several of which interact in ways that depend critically on precisely which antiretroviral agents a patient is taking. A 42-year-old man with a history of alcohol use disorder and poor adherence to highly active antiretroviral therapy (HAART) presented with progressive weight loss and gastroenteritis, and was investigated for advanced HIV disease (CD4 count, full blood count with differential, chest radiograph, and urine TB lipoarabinomannan). He was restarted on HAART and treated with intravenous ciprofloxacin, intravenous metronidazole, oral albendazole, cotrimoxazole, oral zinc, and intravenous fluids. Using a structured Subjective–Objective–Assessment–Plan (SOAP) pharmaceutical care workup, the clinical pharmacist identified non-adherence, a generically stated interaction between HAART and both ciprofloxacin and albendazole, and a need for immune-supportive vitamins. Independent re-appraisal for this report identified that the specific class of HAART was not recorded anywhere in the documentation — a gap that itself precludes meaningful assessment of the very interactions the original plan flagged, since the clinically relevant mechanisms in this case (cation-chelation with zinc, cytochrome P450 3A4-mediated effects on albendazole, and additive renal transporter inhibition with cotrimoxazole) each depend on whether the regimen is integrase-inhibitor-, non-nucleoside reverse-transcriptase-inhibitor-, or protease-inhibitor-based. The patient's diarrhoea improved with formation of harder stool, adherence counselling was delivered, and he remained admitted for completion of the advanced HIV disease workup at the time of documentation closure. This case illustrates that documentation completeness is itself a modifiable drug therapy problem: a pharmaceutical care plan can correctly identify that an interaction exists in principle while being unable to characterise its direction, magnitude, or management without the specific regimen recorded. We recommend that antiretroviral regimen and drug class be a mandatory, structured field in pharmaceutical care documentation for any patient living with HIV