Butorphanol

Limits on what this shows

• Key negative or null findings: No human butorphanol testosterone, LH or DHEAS measurement was located. Spiradoline, a pure kappa agonist, raised prolactin, growth hormone and cortisol in six healthy men [14] (Tier C, butorphanol not in that study), so kappa activity does not uniformly suppress the axis.
• At-risk subgroups: Not established for butorphanol. Label wording applies to extended use of opioids in general [1][2].
• Counter-evidence and confounders: Chronic pain, obesity, age and co-medication lower testosterone independently. The cell result is rat, in vitro, and at concentrations far above clinical blood levels. Butorphanol is a mixed mu partial agonist and antagonist with kappa agonism [7][8][15], so extrapolation from full mu agonists is uncertain.

Regulatory status

Nasal spray label, Clinical Pharmacology, Effects on the Endocrine System: opioids "inhibit the secretion of adrenocorticotropic hormone (ACTH), cortisol, and luteinizing hormone (LH) in humans" and extended use "may influence the hypothalamic-pituitary-gonadal axis, leading to androgen deficiency" [1]. The injection label carries the same sentences [2][3]; the Pfizer injection postmarketing list says "Cases of androgen deficiency have occurred with use of opioids for an extended period of time" [3]. The wording is class-wide ("opioids"); no butorphanol-specific frequency is given. Read through summarizing fetch tools.

Population evidence, this drug in cohort

None found. The two human androgen cohorts opened do not qualify: Rubinstein and Carpenter [10] (1,159 men on a single opioid, hydrocodone referent) names fentanyl, methadone, oxycodone and hydrocodone in its abstract, and butorphanol is not named (Tier C, not in cohort). A veterans series [11] reports testosterone against morphine-equivalent dose without naming any opioid (butorphanol not named). A PubMed listing for butorphanol with androgen, testosterone, cortisol, ACTH and prolactin terms [40] returned one butorphanol-specific hormone record (the rat study below); 29 further PMIDs on that listing were not shown by the fetch tool and were not examined.

Tier B, this drug

Li et al. 2024 [9]: Leydig cells isolated from 35-day-old male rats, treated in vitro with butorphanol for 3 hours at 0.5 to 50 micromolar. Androgen secretion fell at 5 and 50 micromolar; at 50 micromolar butorphanol also blocked the androgen rise normally triggered by LH, 8-bromo-cAMP, 22R-hydroxycholesterol and pregnenolone. It lowered expression of Cyp11a1, Srd5a1, Akr1c14 and Lhcgr and directly inhibited the activity of HSD3B1 and SRD5A1. Abstract reconstructed from an OpenAlex record and read through a summarizing fetch tool. For scale, the nasal label gives peak blood levels of 0.9 to 1.04 ng/mL after a 1 mg dose [1], about 3 nanomolar for the free base (molecular weight 327.5 from the formula C21H29NO2), so 5 micromolar is roughly 1,600 times higher. The study does not show a clinically relevant effect.

Mechanism

Named in the labels: opioid suppression of LH and the hypothalamic-pituitary-gonadal axis [1][2]. Named in the cell study: steroidogenic enzyme inhibition and reduced enzyme gene expression at supraclinical concentrations [9].

Ceiling reached and why

Yellow. Orange would require a human cohort or trial with butorphanol users and a measured hormone outcome; the label statement alone gives no butorphanol-specific effect size or comparator.

Counter-evidence held on record

Framing caution for the consumer surface This is a possible hormone effect of long-term opioid therapy named on the label. It is not a nutrient deficiency, and no vitamin, mineral or hormone supplement is indicated by this entry. Testing and treatment belong with a clinician.

Limits on what this shows

• Key negative or null findings: No butorphanol-specific adrenal insufficiency case series was located. The canine result is a single acute dose in healthy dogs and does not model chronic use.
• At-risk subgroups: Patients on more than one month of continuous opioid therapy (label wording) [1]. Butorphanol nasal spray is often prescribed for intermittent headache use; whether that exposure is sufficient is not addressed by any source opened.
• Counter-evidence and confounders: Pain, surgical stress, anesthetic co-medication and species differences. Glucocorticoid co-treatment would suppress the axis independently.

Regulatory status

Nasal spray label Warnings: "Cases of adrenal insufficiency have been reported with opioid use, more often following greater than 1 month of use"; the patient counseling section says to inform patients that opioids could cause adrenal insufficiency, "a potentially life-threatening condition" [1]. The injection label carries the same warning sentence [2]. Class wording, not butorphanol-specific. The older-format nasal label pages list adrenal insufficiency symptoms as nausea, vomiting, anorexia, fatigue, weakness, dizziness and low blood pressure [4].

Population evidence, this drug in cohort

No human study of butorphanol and cortisol, ACTH or adrenal function was opened.

Tier B, this drug (animals)

Dogs [12]: randomized four-period crossover, 12 healthy Beagles, butorphanol 0.3 mg/kg IV versus saline, dexmedetomidine and trazodone. Median basal cortisol 11.75 (range 2.50 to 23.00) versus 1.27 (0.74 to 2.10) micrograms/dL after saline, P<0.0001; post-ACTH cortisol 17.05 (12.40 to 26.00) versus 13.75 (10.00 to 18.60), P<0.0001. Butorphanol RAISED cortisol, the opposite direction to the label sentence. Horses [13]: randomized blinded trial, 31 horses after celiotomy, butorphanol infusion 13 micrograms/kg/hour for 24 hours versus saline; plasma cortisol was significantly lower in treated horses at 2, 8, 12, 24, 36 and 48 hours (numbers not on the page read), with better behavior scores, so lower cortisol may reflect less pain. Both read as abstract or results summaries through fetch tools.

CLASS EXTRAPOLATION: cohort test

Spiradoline [14]: six healthy men, intramuscular doses, dose-dependent rises in prolactin, growth hormone and cortisol (Tier C; butorphanol NOT in that study; abstract read). It shows that a kappa agonist can raise cortisol in humans, again opposite to the label sentence.

Mechanism

Named in the injection label: opioids inhibit ACTH and cortisol secretion [2]. For butorphanol in animals the direction is species- and setting-dependent, so no single mechanism is established.

Counter-evidence held on record

Framing caution for the consumer surface A hormone-axis monitoring point, not a nutrient finding. Fatigue, nausea and low appetite are non-specific and should be evaluated by a clinician. No supplement is implied.

Limits on what this shows

• Key negative or null findings: No serum sodium measurement in butorphanol users was found. Two hyponatremia case-report pages surfaced by a search did not mention butorphanol [38].
• Counter-evidence and confounders: Diuretics, SSRIs, surgery, heart or liver disease and fluid replacement alter sodium independently. The human diuresis was seen in opioid-experienced volunteers after naltrexone, not in ordinary clinical use.

Regulatory status

No hyponatremia, SIADH, antidiuretic hormone or diuretic-interaction wording was returned for the nasal spray label [1] or the injection label [2]. These are summarizer keyword results from the first 100,000 characters of each label and are not proof of absence. The nasal spray contains sodium chloride, citric acid and benzethonium chloride (Description section) [1]; this is formulation text, not a nutrient finding.

Population evidence, this drug in cohort

Walsh et al. 2008 [15]: ten healthy volunteers with opioid abuse histories, double-blind placebo-controlled, 15 sessions; butorphanol 0 to 12 mg after naltrexone 0 to 30 mg. Butorphanol alone produced mu-type effects (miosis, respiratory depression); naltrexone pretreatment increased butorphanol-induced diuresis, which the authors read as unmasked kappa activity. Urine output and osmolality were measured for 4 hours; serum sodium was not reported in the abstract read.

Tier B, this drug (animal)

Craft et al. 2000 [16]: rats, butorphanol 0.3 to 3.0 mg/kg produced diuresis with no sex difference before body-weight correction and slightly greater diuresis per kg in females after correction (abstract summary only).

CLASS EXTRAPOLATION: cohort test

Kappa agonists bremazocine and U-50,488 markedly suppressed vasopressin in rats [17] (butorphanol NOT tested; abstract only). Spiradoline-class compound U-62,066E in human volunteers raised urine volume to 2.6 times control, lowered urine osmolality to 20% of baseline and left urinary sodium, potassium and chloride excretion unchanged [18] (butorphanol NOT tested; abstract only; title, authors and year not shown on the page read).

Mechanism

Kappa-receptor suppression of vasopressin release and water diuresis (animal and human kappa-agonist literature [16][17][18]). The mu-receptor ADH-release mechanism stated for other opioids in sibling labels is not supported by any butorphanol source opened.

Counter-evidence held on record

Framing caution for the consumer surface Not a deficiency. Neither adding salt nor changing water intake is implied by this entry; any sodium concern is a clinician decision.

Limits on what this shows

• Key negative or null findings: A meta-analysis of nine butorphanol PCA trials [20] (426 butorphanol, 420 comparator patients) reported nausea, vomiting, itching and dizziness but not constipation. Rabbit effect was not equipotent-matched and used males only [19].
• Counter-evidence and confounders: Immobility, surgery, anesthetic co-medication and diet affect transit. Differences between rabbits, horses and people limit transfer.

Regulatory status

Injection label: "Butorphanol causes a reduction in motility associated with an increase in smooth muscle tone," with colonic tone raised "to the point of spasm, resulting in constipation" [3]; propulsive peristaltic waves in the colon are decreased [1][2]. Nasal spray clinical trials list "anorexia, constipation, dry mouth, nausea and/or vomiting, diarrhea" at 1% or more [1]. Counseling text: advise patients of the potential for severe constipation [1][2]. No placebo-controlled incidence figure was retrieved.

Tier B, this drug

Rabbits [19]: 44 analyzed, butorphanol 5 mg/kg IM five minutes before barium; caecum repletion LSM 4.08 +/- 0.79 versus morphine 7.97 +/- 0.83 and tramadol 1.22 +/- 0.79; effect significant only at 30 minutes and 1 hour (morphine to 3 hours); caecal emptying began at 12 hours with butorphanol and morphine versus 6 hours in controls and tramadol; stomach and pyloroduodenal contractions unchanged; no ileus. Horses [13]: median time to first feces 15 hours with butorphanol infusion versus 4 hours with saline (31 horses after celiotomy).

Mechanism

Named in the labels: reduced colonic propulsion with increased smooth muscle tone [1][2][3].

Counter-evidence held on record

Framing caution for the consumer surface A drug effect that clinicians manage; it is not evidence of any vitamin or mineral shortfall. Bowel-regimen choice belongs with the prescriber.

Limits on what this shows

• Key negative or null findings: No taste or appetite measurement tied to dietary intake was located. Opioid-induced esophageal dysfunction is listed as a postmarketing reaction for opioids in general [4]; not butorphanol-specific.
• Counter-evidence and confounders: Migraine, pain, post-operative state and sedation all reduce appetite independently; nasal congestion can alter taste perception.

Regulatory status

Nasal spray label: somnolence 49%, dizziness 23% and nausea and/or vomiting 8% were the most frequent reactions across trials; nasal congestion 13% and insomnia 11% in long-term trials only; at 1% or more, digestive events "anorexia, constipation, dry mouth, nausea and/or vomiting, diarrhea" and special-senses events including "unpleasant taste" [1]. The injection label lists nausea and/or vomiting at 1 mg or more by any route [2]. Tier D patient page lists "bad taste in your mouth" for the nose spray and decreased appetite for all products [32].

Population evidence, this drug in cohort

Nasal spray trial incidence for taste and anorexia was not on the pages read. A meta-analysis of nine butorphanol PCA trials [20] found fewer events than comparators: nausea RR 0.30 (95% CI 0.22 to 0.42), vomiting RR 0.35 (0.25 to 0.49), pruritus RR 0.29 (0.13 to 0.64), dizziness RR 0.45 (0.32 to 0.63). Comparators were morphine, fentanyl, sufentanil or saline; this is an active-comparator result in injection post-operative PCA and does not test intake. Read through a summarizing fetch tool; one printed interval in that paper was internally inconsistent.

Mechanism

Present for mechanism class H (changed intake via taste, appetite, nausea, sedation) by label adverse reactions only. The magnitude and duration for nutrient intake are unknown.

Counter-evidence held on record

Framing caution for the consumer surface Not a nutrient deficiency. Persistent loss of appetite or weight on this medicine should be raised with a clinician; no supplement is implied.

Limits on what this shows

• Why no grade: The dual condition in Step 7 was met: no Tier B or C source (no butorphanol olfactory study in animals or people, and no class study of kappa or mixed agonist-antagonist opioids on olfaction was reached), and no circulating consumer claim (the consumer pages opened [32][33] mention "bad taste" and nasal irritation for the spray but not smell). Nasal congestion (13% in long-term trials), rhinitis, epistaxis and nasal irritation are listed adverse reactions [1], but they are not olfactory measurements and are not graded here.

Channels tried

DailyMed nasal spray label [1] (keyword queries for smell, olfactory, anosmia: absent in the first 100,000 characters read and the last 5,741 characters were then read for nasal and smell terms: absent); older-format nasal label pages [4] (page 7 blocked by robots rules); injection labels [2][3]; WebSearch for butorphanol nasal spray with olfactory function, anosmia, taste and mucosa safety (returned unrelated records; a second query on ciliary function and nasal mucosa returned veterinary nasal-permeation formulation papers, not opened); PubMed record 14575403 (fluticasone and smell; butorphanol not mentioned) [35]; PLoS ONE 2009 Zicam and other intranasal agents in mice and human nasal explants (butorphanol not mentioned) [36]; Pharmaceutics 2021 nasal spray ciliotoxicity in a 3D human nasal model (mometasone; butorphanol not mentioned) [37]. A PubMed listing for butorphanol with olfaction terms was not run (see access note); the web search budget was then exhausted.

Gap type

Genuine gap on everything reached, with a partial tooling limitation: the PubMed, Europe PMC and Crossref searches that would settle it were rate-limited, and web search became unavailable. Re-check when those are reachable (queries: butorphanol AND (olfaction OR smell OR anosmia OR "nasal mucosa")).

Counter-evidence held on record

Framing caution for the consumer surface Not a statement that the spray is safe for smell. It means no butorphanol-specific olfaction evidence was found. Persistent loss of smell or taste should be reported to a clinician.