Epinephrine auto-injector needle length

Table 1 Auto-injector needles available in North America and Europe in 2019

EAI	Lower and upper limits for needle length	Naked skin		With thick clothes 3 mm		Pressure against the thigh
EAI	Lower and upper limits for needle length	Skin to muscle distance −2 mm (acc. to Diacono)	Skin to bone distance full length	Skin to muscle distance (-3 mm clothes and −2 mm) = − 5 mm	Skin to bone distance full pene-trating needle length − 3 mm	Pressure against the thigh
HPEAI^a
Epipen Jr^® 0.15 mg	Lower limit	8	10	5	7	Press hard
Epipen Jr^® 0.15 mg	Upper limit	13	15	10	12
Epipen^® 0.3 mg	Lower limit	11	13	8	10
Epipen^® 0.3 mg	Upper limit	16	18	13	15
Auvi-Q 0.1 mm	Lower limit	4.4	6.4	1.4	3.4	Push firmly
Auvi-Q 0.1 mm	Upper limit	6.9	8.9	3.9	5.9
Auvi-Q 0.15 mg	Lower limit	9.4	11.4	6.4	8.4
Auvi-Q 0.15 mg	Upper limit	12	14.0	9	11
Auvi-Q 0.3 mg	Lower limit	12.7	14.7	9.7	11.7
Auvi-Q 0.3 mg	Upper limit	15.3	17.3	12.3	14.3
LPEAI^b
Emerade^® 0.15 mg	Lower limit	13	15	10.0	12.0	Slight pressure
Emerade^® 0.15 mg	Upper limit	14.7	16.7	11.7	13.7
Emerade^® 0.3 mg	Lower limit	20.1	22.1	17.1	19.1
Slight preesure	Upper limit	21.6	23.6	18.6	20.6
Emerade^® 0.5 mg	Lower limit	20.1	22.1	17.1	19.1
Emerade^® 0.5 mg	Upper limit	21.6	23.6	18.6	20.6

Needle lengths are given according to the manufacturers’ approved specifications. The skin to muscle distance is based on Diacono et al. [7] by subtracting 2 mm from the penetrating needle length. The increased distance to muscle, i.e. 2 mm for the eye of the needle. The skin to bone distance is based on the full length of the needle. Both skin to muscle distance and skin to bone distance are given for the case injection is performed on naked skin and with winter cloths. The thickness of winter clothes is proposed to be 3 mm, but can vary among individuals
^aHPEAI, These devices are high-pressure epinephrine autoinjectors, HPEAIs
^bThis device is a low-pressure epinephrine autoinjector, LPEAI

ISSN: 1710-1492