Amprenavir-induced maculopapular exanthem followed by desensitization in a patient with late-stage human immunodeficiency virus

Old dog begging for new tricks: current practices and future directions in the diagnosis of delayed antimicrobial hypersensitivity

PURPOSE OF REVIEW

Antimicrobials are a leading cause of severe T cell-mediated adverse drug reactions (ADRs). The purpose of this review is to address the current understanding of antimicrobial cross-reactivity and the ready availability of and evidence for in-vitro, in-vivo, and ex-vivo diagnostics for T cell-mediated ADRs.

RECENT FINDINGS

Recent literature has evaluated the efficacy of traditional antibiotic allergy management, including patch testing, skin prick testing, intradermal testing, and oral challenge. Although patch and intradermal testing are specific for the diagnosis of immune-mediated ADRs, they suffer from drug-specific limitations in sensitivity. The use of ex-vivo diagnostics, especially enzyme-linked immunospot, has been highlighted as a promising new approach to assigning causality. Knowledge of true rates of antimicrobial cross-reactivity aids empirical antibiotic choice in the setting of previous immune-mediated ADRs.

SUMMARY

In an era of increasing antimicrobial resistance and use of broad-spectrum antimicrobial therapy, ensuring patients are assigned the correct 'allergy label' is essential. Re-exposure to implicated antimicrobials, especially in the setting of severe adverse cutaneous reaction, is associated with significant morbidity and mortality. The process through which an antibiotic label gets assigned, acted on and maintained is still imprecise. Predicting T cell-mediated ADRs via personalized approaches, including human leukocyte antigen-typing, may pave future pathways to safer antimicrobial prescribing guidelines.

A HAART-Breaking Review of Alternative Antiretroviral Administration: Practical Considerations with Crushing and Enteral Tube Scenarios

Selection of an appropriate antiretroviral regimen for the patient infected with human immunodeficiency virus can be challenging, as various considerations must be taken into account including viral resistance mutations, patient comorbidities, drug interactions, and the potential for drug-related adverse effects and toxicities. Treatment is further complicated when a clinical scenario arises requiring an alteration in the dosage form. Factors ranging from dysphagia to administration through an enteral feeding tube can affect decisions regarding antiretroviral dosage forms. Limited pharmacokinetic data exist regarding the alteration of antiretroviral medications from their original form. Bioavailability may vary substantially between dosage forms, which can lead to unpredictable drug concentrations. Supratherapeutic or subtherapeutic antiretroviral drug concentrations can result in increased toxicity, virologic failure, or the emergence of drug resistance. We performed a systematic literature search to review the available antiretroviral literature on the modification of solid dosage forms as well as alternative routes of administration of oral antiretroviral agents and their application to clinical practice.

Drug hypersensitivity in human immunodeficiency virus-infected patient: challenging diagnosis and management

Human immunodeficiency virus (HIV)-infected patients present complex immunological alterations. Multiple drugs that usually prescribed for prevention or treatment of opportunistic infections and antiretroviral pose these patients a higher risk of developing drug hypersensitivity. All antiretroviral agents and drugs to treat opportunistic infections have been reported to cause drug hypersensitivity reactions. Allergic reactions with antiretroviral are not restricted to older agents, although newer drugs usually more tolerated. Cutaneous adverse drug reactions are the most common manifestation of drug hypersensitivity in HIV, typically manifesting as maculopapular rash with or without systemic symptoms in the presence or absence of internal organ involvement. The onset of an allergic reaction is usually delayed. Severe drug hypersensitity reactions as erythema multiforme, Stevens Johnson syndrome and toxic epidermal necrolysis develop more often in HIV-infected patients compared to other populations. Mild to moderate rash without systemic symptom or organ involvement usually do not need drug discontinuation. Appropriate diagnosis and management of drug hypersensitivity reactions are essential, especially in patients with very low CD4+ T-cell count and multiple opportunistic infections. Clinicians should aware of different half-life of each drug when decided to stop the drug. Knowledge of the metabolism, recognition of the risk factors, and the ability to suggest the probability of particular drug as causative are also important points. A step wise rechallenge test or desensitization with the offending drug might be a preferable action and more commonly used in managing drug hypersensitivity in HIV-infected patients. Desensitization protocols have been successfully done for several antiretroviral and opportunistic infection drugs.

Desensitization in delayed drug hypersensitivity reactions -- an EAACI position paper of the Drug Allergy Interest Group

Drug hypersensitivity may deprive patients of drug therapy, and occasionally no effective alternative treatment is available. Successful desensitization has been well documented in delayed drug hypersensitivity reactions. In certain situations, such as sulfonamide hypersensitivity in HIV-positive patients or hypersensitivity to antibiotics in patients with cystic fibrosis, published success rates reach 80%, and this procedure appears helpful for the patient management. A state of clinical tolerance may be achieved by the administration of increasing doses of the previously offending drug. However, in most cases, a pre-existent sensitization has not been proven by positive skin tests. Successful re-administration may have occurred in nonsensitized patients. A better understanding of the underlying mechanisms of desensitization is needed. Currently, desensitization in delayed hypersensitivity reactions is restricted to mild, uncomplicated exanthems and fixed drug eruptions. The published success rates vary depending on clinical manifestations, drugs, and applied protocols. Slower protocols tend to be more effective than rush protocols; however, underreporting of unsuccessful procedures is very probable. The decision to desensitize a patient must always be made on an individual basis, balancing risks and benefits. This paper reviews the literature and presents the expert experience of the Drug Hypersensitivity Interest Group of the European Academy of Allergy and Clinical Immunology.

Hypersensitivity and Desensitization to Darunavir in a Case of HIV Infection with Triple-Class Drug Resistance

We report on a case of severe cutaneous reaction to darunavir/r and a successful desensitization protocol. The patient was a 41-year-old female, known to be HIV infected for 18 years and who had received several drug regiments in the past. As a consequence, her virus had triple-class mutations but was susceptible to darunavir/r. Her CD4 was 200 cells/mm3 and HIV viral load 56,000 copies/mL. Eight days after initiation of darunavir/r the patient developed a severe pruritic vesicular extended cutaneous allergic reaction which required cessation of all drugs. Due to the severity of the allergic reaction no rechallenge was done. After the patient's recovery, the virus was found to be susceptible only to maraviroc, raltegravir, and darunavir/r. Since darunavir/r was an essential component in treating this triple-class mutated virus, a desensitization protocol was applied successfully. Six months after desensitization, the patient is asymptomatic, compliant, and her HIV viral load remains at <20 copies/mL.

Administration of antiretroviral medication via enteral tubes

PURPOSE

Case reports and other published or manufacturer-provided data on the administration of antiretroviral agents through enteral feeding tubes are reviewed.

SUMMARY

There is very limited published evidence to guide clinicians in the delivery of therapies for human immunodeficiency virus (HIV) infection by feeding tubes, especially crushed tablets and capsule contents. A search of the primary literature (through February 2012) identified a total of nine articles describing the delivery of highly active antiretroviral therapy (HAART) agents via gastrostomy (G), jejunostomy, and other feeding tubes; correspondence with pharmaceutical manufacturers yielded additional information. Most of the published evidence (from two prospective studies, one retrospective study, and six case reports) pertains to the treatment of HIV-infected children (33 of 40 cases). Although not a primary endpoint of any of the reviewed studies, viral suppression was documented in 29 of the 40 patients referenced in the reviewed articles. Manufacturer-provided information indicates that crushed darunavir tablets in suspension, as well as oral solutions of ritonavir and lopinavir-ritonavir, can be administered through G-tubes without significant loss of therapeutic efficacy.

CONCLUSION

Data regarding enteral feeding tube administration are available for 63% of commercially available oral HAART agents and are primarily limited to case reports specific to the pediatric population.

Hypersensitivity reactions to HIV therapy

Many drugs used for the treatment of HIV disease (including the associated opportunistic infections) can cause drug hypersensitivity reactions, which vary in severity, clinical manifestations and frequency. These reactions are not only seen with the older compounds, but also with the newer more recently introduced drugs. The pathogenesis is unclear in most cases, but there is increasing evidence to support that many of these are mediated through a combination of immunologic and genetic factors through the major histocompatibility complex (MHC). Genetic predisposition to the occurrence of these allergic reactions has been shown for some of the drugs, notably abacavir hypersensitivity which is strongly associated with the class I MHC allele, HLA-B*5701. Testing before the prescription of abacavir has been shown to be of clinical utility, has resulted in a change in the drug label, is now recommended in clinical guidelines and is practiced in most Western countries. For most other drugs, however, there are no good methods of prevention, and clinical monitoring with appropriate (usually supportive and symptomatic) treatment is required. There is a need to undertake further research in this area to increase our understanding of the mechanisms, which may lead to better preventive strategies through the development of predictive genetic biomarkers or through guiding the design of drugs less likely to cause these types of adverse drug reactions.

Clinical applications of drug desensitization in the Asia-Pacific region

Drug desensitization is the induction, within hours to days, of a temporary state of tolerance to a drug which the patient has developed a hypersensitivity reaction to. It may be used for IgE and non-IgE mediated allergic reactions, and certain non-allergic reactions. The indication for desensitization is where no alternative medications are available for the treatment of that condition, and where the benefits of desensitization outweigh the risks. Desensitization is a therapeutic modality for drug allergy (similar to allergen specific immunotherapy for allergic rhinitis and insect venom anaphylaxis). In contrast, the drug provocation test is a diagnostic modality used to confirm or refute the diagnosis of drug allergy. This review discusses the clinical applications of desensitization for the treatment of common infectious, metabolic and cardiovascular diseases, and oncological conditions in the Asia-Pacific region.

Dermatologic adverse effects of antiretroviral therapy: recognition and management

Despite the decrease in opportunistic infections associated with HIV in the highly active antiretroviral treatment (HAART) era, a significant number of patients still present with skin pathology, some of which can be attributed directly or indirectly to antiretroviral therapy. The non-nucleoside reverse transcriptase inhibitors exhibit a class effect with regard to skin adverse manifestations, and the spectrum of disease can vary from a mild morbilliform rash to Stevens-Johnson syndrome. Certain protease inhibitors are associated with rash, and indinavir causes retinoid-like manifestations such as paronychia, alopecia, ingrown toe-nails, and curling of straight hair. Abacavir, a nucleoside reverse transcriptase inhibitor, is notorious for causing a hypersensitivity reaction in select patients. The fusion inhibitor enfuvirtide causes injection-site reactions in the overwhelming majority of patients, although a new method of delivery has decreased the rate and severity of these reactions. A syndrome of lipoatrophy with or without lipohypertrophy, often termed lipodystrophy, has been described in patients receiving HAART. Potential management of lipoatrophy includes switching antiretrovirals and surgical treatment with facial fillers. Lastly, skin manifestations of the immune reconstitution inflammatory syndrome, including herpes zoster and warts, must be recognized and treated accordingly. In the evaluation of the individual HIV-infected patient receiving antiretroviral therapy who presents with a skin disorder, clinicians should consider the CD4 cell count as a marker of the degree of immunodeficiency, the specific antiretrovirals used, and the timing of the initiation of antiretroviral therapy in order to formulate a rational differential diagnosis. Management should be individualized based on the specific drug that is implicated and the severity of the reaction.