Nebulized Fentanyl for Pain Relief in Healthy Adults

Inclusion Criteria:

* Age ≥ 18 years and \< 68 years
* BMI between 19 and 29 kg/m²
* Affiliation to a social security scheme
* Adult who has read and understood the information letter and signed the consent form
* Woman capable of procreating (a woman is considered capable of procreating, i.e. fertile, after menarche and until she becomes menopausal, unless she is definitely sterile ) having very effective contraception (combined hormonal contraception (containing estrogens and progestins) associated with inhibition of ovulation, progestin-only hormonal contraception associated with inhibition of ovulation, intrauterine device, hormone-releasing intrauterine system (IUS), bilateral tubal occlusion, vasectomized partner, sexual abstinence) for 1 year and a negative urine pregnancy test at inclusion and during the duration of the study.
* Woman definitely surgically sterile (hysterectomy, bilateral salpingectomy and bilateral oophorectomy). Postmenopausal woman: The postmenopausal state is defined by the absence of periods for 12 months without any other medical cause.

Exclusion Criteria:

* Weight \< 50 kg
* Taking long-term painkillers or narcotics
* Sharp pain
* Stable chronic pain (\>3 months, with or without long-term treatment)
* Known chronic pathology stabilized or decompensated (hypertension, renal, cardiac, hepatic insufficiency, etc.)
* Stable or decompensated chronic respiratory pathology
* Chronic neuropsychiatric pathology likely to modify the pain threshold
* Long-term treatment with an action on the nervous system such as respiratory depression: benzodiazepines, neuroleptics, agonist/antagonist of the opioid system
* Treatment or toxicant whose association is not recommended with fentanyl (alcohol, cannabis, etc.)
* Central nervous system modulator treatment
* Pathologies blocking the pupillary response: Claude-Bernard-Horner syndrome, Adie syndrome, Argyll-Robertson pupil, senile miosis, dysautonomic neuropathy (advanced diabetes, systemic amyloidosis), cataract
* Treatment responsible for fluctuation in PUAL measurements: parasympathetic modulators (clonidine, dexmedetomidine, droperidol, metoclopramide)
* No-indication to FENTANYL PIRAMAL 100µg/2mL, solution for injection in ampoule
* No-indication to PROAMP SODIUM CHLORIDE 0.9%, solution for injection
* Ongoing treatment with nasal vasoconstrictors
* Peripheral oxygen saturation less than 93%
* Alteration of cognitive state: comprehension disorder, language disorder, memory disorder, confusion
* Deaf or mute patient
* Usual heart rate such as HR\< 40 bpm and/or hypotension with systolic blood pressure SBP\< 100 mm Hg
* Atrioventricular block on ECG
* History of cataract surgery
* Confirmed or suspected covid 19 / active flu infection less than 15 days old
* Allergy to plastic
* Pregnant or parturient or breastfeeding woman or proven absence of contraception
* Person deprived of liberty by an administrative or judicial decision or person placed under judicial protection/under guardianship or curatorship
* Person participating in research participating in another trial / having participated in another trial within 2 weeks
* History of illness or psychological or sensory abnormality likely to prevent the subject from fully understanding the conditions required for participation in the protocol or preventing them from giving informed consent