Epinephrine and its use in anaphylaxis: current issues

Effect of epinephrine on platelet-activating factor-stimulated human vascular smooth muscle cells

BACKGROUND

Animal and human data show that platelet-activating factor (PAF) mediates the life-threatening manifestations of anaphylaxis. Although administration of epinephrine is the mainstay of therapy of acute anaphylaxis, the interaction between epinephrine and PAF has not been studied. In particular, the effect of the timing of epinephrine administration on the action of PAF has not been examined.

OBJECTIVE

Using human vascular smooth muscle cells (HVSMCs), we examined the effect of timing of epinephrine addition on the action of PAF.

METHODS

The effect of epinephrine on PAF-mediated prostaglandin E(2) (PGE(2)) release from human aortic smooth muscle cells was examined. Epinephrine was added at various times before and after PAF stimulation.

RESULTS

HVSMCs stimulated with PAF released PGE(2) in a concentration- and time-dependent manner. Whereas preincubation of HVSMCs with epinephrine before the addition of PAF suppressed PGE(2) release, treatment with epinephrine after PAF stimulation was less effective with time after PAF stimulation. PGE(2) release was suppressed by means of preincubation with 8-bromo-cyclic AMP and forskolin.

CONCLUSIONS

PAF induced PGE(2) release from HVSMCs in a concentration- and time-dependent manner, and early addition of epinephrine was essential for the control of PAF-induced PGE(2) release. Epinephrine was most effective when administered before stimulation with PAF but was progressively less effective with time after PAF stimulation.

The TEN study: time epinephrine needs to reach muscle

BACKGROUND

An epinephrine autoinjector (EAI) is designed to deliver epinephrine into the vastus lateralis muscle. Several studies have demonstrated both patient and physician difficulties in correctly using EAIs, specifically premature removal of the device from the thigh.

OBJECTIVE

To evaluate the correlation between duration of injection with an EAI and amount of epinephrine absorbed into muscle tissue.

METHODS

Twenty-one EAI devices (0.3 mL) were used to determine the amount of epinephrine injected into marbleized beef during 7 time periods. A digital scale was used to record preinjection and postinjection weights of EAIs and beef. The weight difference between the preinjection and postinjection periods of the EAIs was used to calculate the total amount of epinephrine released and available for absorption into the marbleized beef. The difference between the preinjection and postinjection beef weight was used to determine the amount of epinephrine absorbed into the meat.

RESULTS

The correlation with duration of injection for both the amount of epinephrine absorbed and released was 0.321 (P = .48). At all intervals, 95.9% or more of epinephrine was absorbed into the marbleized beef. The correlation with duration of injection and percent of epinephrine absorbed was 0.464 (P = .29). There were no time periods that were significantly different from the percentage of epinephrine absorbed by the marbleized beef at 10 seconds (analysis of variance P = .16).

CONCLUSION

No linear relationship between time and amount of epinephrine injected or absorbed into muscle tissue was demonstrated. These data suggest that holding the device in place for 1 second is as effective as 10 seconds.

Anaphylaxis pathogenesis and treatment

Anaphylaxis is a serious allergic reaction that is rapid in onset and sometimes leads to death. Understanding mechanisms, triggers, and patient-specific risk factors for severe or fatal anaphylaxis is critically important. Diagnosis of anaphylaxis is currently based on established clinical criteria. Epinephrine (adrenaline) is the first-line medication for anaphylaxis treatment and delay in injecting it contributes to biphasic reactions, hypoxic-ischemic encephalopathy, and fatality. Here, we focus on four important areas of translational research in anaphylaxis: studies of potential new biomarkers to support the clinical diagnosis of anaphylaxis, laboratory tests to distinguish allergen sensitization from clinical risk of anaphylaxis, the primary role of epinephrine (adrenaline) in anaphylaxis treatment, and strengthening the overall evidence base for anaphylaxis treatment.

Immediate and delayed-onset systemic reactions after subcutaneous immunotherapy injections: ACAAI/AAAAI surveillance study of subcutaneous immunotherapy: year 2

BACKGROUND

Incidences of subcutaneous immunotherapy (SCIT) related systemic reactions (SRs) and fatal reactions (FRs) are not well defined, nor are delayed-onset SRs and their treatment.

OBJECTIVES

To estimate SCIT-related SRs/FRs, and the incidence and treatment of delayed-onset SRs.

METHODS

In 2008 and 2009, American Academy of Allergy, Asthma & Immunology (AAAAI) and American College of Allergy Asthma & Immunology (ACAAI) members completed a survey about SCIT-related SR severity (grade 1 = mild; grade 2 = moderate; grade 3 = severe anaphylaxis). In 2009, members reported the time of onset and use of epinephrine (EPI), with early onset defined as beginning ≤30 minutes, and delayed onset beginning more than 30 minutes after injections.

RESULTS

As in year 1, no FRs were reported during year 2 (630 total practices responded). Among 267 practices providing data on the timing of SRs, 1,816 early-onset SRs (86%) and 289 (14%) delayed-onset SRs were reported. Fifteen percent (226/1,519) of grade 1, 10% (54/538) of grade 2, and 12.5% (9/72) of grade 3 SRs were delayed-onset. Among early-onset SRs, EPI was given for 71% of grade 1, 93% of grade 2, and 94% of grade 3s. Among delayed-onset SRs, EPI was given for 56% of grade 1, 67% of grade 2, and 100% of grade 3s (P = .0008 for difference in EPI administration based on severity; P = .07 based on time of onset).

CONCLUSIONS

Delayed-onset SRs are less frequent than previously reported. Epinephrine was given less frequently for grades 1 and 2 (but not grade 3) delayed-onset SRs compared with early-onset SRs. Further study of prescribing self-injectable EPI for SCIT patients in the event of delayed-onset SRs may be warranted.

Extremely low prevalence of epinephrine autoinjectors in high-risk food-allergic adolescents in Dutch high schools

The aim of the study was to estimate the prevalence of probable food allergy in adolescents aged 11-20 and to examine the frequency of epinephrine autoinjector (EAI) ownership among high-risk individuals. Adolescents were screened followed by a more detailed telephone questionnaire inquiring about suspected food(s), symptoms, diagnosis, and use of an EAI. The participating adolescents were classified as probably or unlikely to be food-allergic. The need for an EAI was assessed. In total, 2284 adolescents completed the screening questionnaire, of which 396 indicated food to be a problem and 168 agreed to be interviewed. Forty-eight adolescents were classified as probably food-allergic, of which eight were not aware of their food allergy. Twenty-three adolescents were considered candidates for an EAI, whereas only two of them had been prescribed this medication. The calculated questionnaire-based prevalence of EAI need was 3.0% (minimal prevalence at least 1.0%), whereas the EAI ownership was 0.09%. In conclusion, we found an alarming under prescription of EAIs in school-going adolescents.

Epinephrine autoinjector refill history in an HMO

Epinephrine can be lifesaving in episodes of anaphylaxis, yet it is underprescribed and underused. Tracking of epinephrine refills over time for patients with a diagnosis of anaphylaxis has not been reported. This study reports on the refill history of 14,677 patients in a large HMO who received an initial dispensing of EpiPen (Dey Pharma, Basking Ridge, NJ) or EpiPen Jr between 2000 and 2006. A total of 6,776 (46%) refilled at least once. Twenty-five percent of the patients who were in the cohort for 5 years or more refilled multiple times, and 11% refilled consistently at all expected refill times. Infants through children 12 years of age were more likely to receive a refill dispensing (63%) compared with teenagers and adults (40%). The most common ICD-9 codes that were linked to the initial epinephrine dispensing were allergic disorder (37%), miscellaneous anaphylaxis/angioedema (23%), hymenoptera/insect bite or sting (14%), and specific or nonspecific food allergy (11%). A total of 79% of patients with a food-related ICD-9 code and 59% of patients with an insect sting-related ICD-9 code refilled epinephrine at least once. An opportunity exists to identify system-based as well as personal barriers in an ongoing effort to provide patients at risk with the tools and empowerment that could reduce their risk during life-threatening anaphylactic reactions.

World allergy organization guidelines for the assessment and management of anaphylaxis

The illustrated World Allergy Organization (WAO) Anaphylaxis Guidelines were created in response to absence of global guidelines for anaphylaxis. Uniquely, before they were developed, lack of worldwide availability of essentials for the diagnosis and treatment of anaphylaxis was documented. They incorporate contributions from more than 100 allergy/immunology specialists on 6 continents. Recommendations are based on the best evidence available, supported by references published to the end of December 2010. The Guidelines review patient risk factors for severe or fatal anaphylaxis, co-factors that amplify anaphylaxis, and anaphylaxis in vulnerable patients, including pregnant women, infants, the elderly, and those with cardiovascular disease. They focus on the supreme importance of making a prompt clinical diagnosis and on the basic initial treatment that is urgently needed and should be possible even in a low resource environment. This involves having a written emergency protocol and rehearsing it regularly; then, as soon as anaphylaxis is diagnosed, promptly and simultaneously calling for help, injecting epinephrine (adrenaline) intramuscularly, and placing the patient on the back or in a position of comfort with the lower extremities elevated. When indicated, additional critically important steps include administering supplemental oxygen and maintaining the airway, establishing intravenous access and giving fluid resuscitation, and initiating cardiopulmonary resuscitation with continuous chest compressions. Vital signs and cardiorespiratory status should be monitored frequently and regularly (preferably, continuously). The Guidelines briefly review management of anaphylaxis refractory to basic initial treatment. They also emphasize preparation of the patient for self-treatment of anaphylaxis recurrences in the community, confirmation of anaphylaxis triggers, and prevention of recurrences through trigger avoidance and immunomodulation. Novel strategies for dissemination and implementation are summarized. A global agenda for anaphylaxis research is proposed.