Cholecystokinin
Evidence: B — Meaningful Human EvidenceGastrointestinal / Gut-Hormone Signaling
Evidence Snapshot
What this grade covers
Applies to native CCK-33 (2 of 3 controlled human studies located showed a significant satiety/food-intake effect; one, PMID 8426911, found no significant effect at physiological concentrations) and to the natural CCK-8 circulating fragment (3 independent controlled human administration studies located, PMID 6294699, 6285318, 9855480; one of these, PMID 9855480, found the apparent satiety effect statistically confounded with nausea/anxiety). This grade does NOT extend to CCK-58, for which no human administration literature was located in this review -- CCK-58-specific claims carry an explicit evidence-boundary statement rather than inherit this grade. Sincalide/Kinevac's own diagnostic-use evidence is graded and represented separately as product-specific regulatory/formulation content, not blended into this native grade despite the confirmed sequence identity to CCK-8.
Regulatory Context
Native Cholecystokinin (CCK-8, CCK-33, CCK-58) is an endogenous hormone and is not itself an FDA-approved drug product. Sincalide, marketed as Kinevac, is a separately regulated, FDA-approved diagnostic drug with the same amino-acid sequence as the natural CCK-8 fragment; its approval covers only its own labeled diagnostic uses and does not extend to cholecystokinin generally.
Research Takeaway
Cholecystokinin circulates in multiple native forms -- including CCK-8, CCK-33, and CCK-58 -- which are not automatically interchangeable in their human evidence base.
Evidence boundary: Do not silently transfer a CCK-33 finding to CCK-58.
See all 5 evidence claims →Quick Summary
Cholecystokinin (CCK) is a digestive gut hormone that circulates in several native forms -- CCK-8, CCK-33, and CCK-58. Controlled human studies of CCK-33 and CCK-8 generally, though not universally, show reduced hunger and food intake; one study found the effect entangled with nausea. Sincalide (Kinevac), a manufactured version of the CCK-8 fragment with an identical amino-acid sequence, is an FDA-approved diagnostic drug -- a distinct, product-specific regulatory story from native CCK's own physiology.
Mechanism & Research Overview
Cholecystokinin (CCK) is a digestive gut hormone that circulates in several native forms -- CCK-8, CCK-33, and CCK-58. Controlled human studies of CCK-33 and CCK-8 generally, though not universally, show reduced hunger and food intake; one study found the effect entangled with nausea. Sincalide (Kinevac), a manufactured version of the CCK-8 fragment with an identical amino-acid sequence, is an FDA-approved diagnostic drug -- a distinct, product-specific regulatory story from native CCK's own physiology.
Evidence Claims
Individual scientific statements drawn from the sources cited below, each shown with the specific evidence boundary that statement does not establish.
Supported
Cholecystokinin circulates in multiple native forms -- including CCK-8, CCK-33, and CCK-58 -- which are not automatically interchangeable in their human evidence base.
Does not establish
Evidence boundary: Do not silently transfer a CCK-33 finding to CCK-58.
Sources: Satiety Effects of Cholecystokinin in Humans; C-Terminal Octapeptide of Cholecystokinin Decreases Food Intake in Obese Men
Supported
Intravenous administration of native CCK-33 or the natural CCK-8 fragment at physiological concentrations has been shown in multiple controlled human studies to reduce hunger, food intake, or meal size, though findings are not fully consistent across studies.
Does not establish
Evidence boundary: One controlled CCK-33 study (PMID 8426911) found no significant effect on food intake or hunger/fullness at physiological concentrations; one CCK-8 study (PMID 9855480) found the apparent effect confounded with nausea/anxiety. This claim must be read together with those limitations.
Sources: Satiety Effects of Cholecystokinin in Humans; Satiety Effects of a Physiological Dose of Cholecystokinin in Humans; C-Terminal Octapeptide of Cholecystokinin Decreases Food Intake in Obese Men; Cholecystokinin Octapeptide Decreases Intake of Solid Food in Man
Supported
No controlled human administration study of CCK-58 specifically was located in this review. CCK-58's human evidence should not be assumed equivalent to CCK-33 or CCK-8's.
Does not establish
Evidence boundary: Absence of evidence after a direct, dedicated search -- not proof that no such evidence exists anywhere, but none was found. Do not state or imply CCK-58 human efficacy data exists.
Supported
Sincalide (marketed as Kinevac) is a synthetically manufactured CCK-8 octapeptide whose amino-acid sequence, including the biologically essential sulfated tyrosine, is identical to the natural CCK-8 fragment.
Does not establish
Evidence boundary: This sequence-identity fact does not mean Sincalide's approved diagnostic use, dosing, or safety profile applies to natural circulating CCK-8, CCK-33, or CCK-58. Do not use this identity fact to inflate native CCK's evidence grade with Sincalide's regulatory approval.
Sources: FDA Label / DailyMed Record for KINEVAC (Sincalide) Injection
Supported
Sincalide (Kinevac) is FDA-approved, since 1976, to stimulate gallbladder contraction for diagnostic imaging and to stimulate pancreatic secretion (used with secretin) prior to duodenal aspiration for pancreatic function testing.
Does not establish
Evidence boundary: This is Sincalide-product-specific regulatory information; it is not an approval of cholecystokinin generally, and does not mean native CCK-33 or CCK-58 are approved for any use. Do not state 'cholecystokinin is FDA-approved' -- only Sincalide/Kinevac carries that status.
Sources: FDA Label / DailyMed Record for KINEVAC (Sincalide) Injection
Safety & Evidence Limitations
Considerations reported in the sources cited on this page — not a complete list of every possible risk, and not medical advice.
Safety Consideration
A controlled human CCK-8 infusion study found the reduction in energy intake was statistically entangled with concurrent nausea and anxiety ratings, raising the possibility that some or all of the apparent satiety effect reflects an aversive response rather than a pure satiety mechanism.Safety Consideration
One of three controlled human CCK-33 studies located (PMID 8426911) found no significant effect on food intake or hunger/fullness ratings at physiological plasma concentrations, directly contradicting a simple 'CCK-33 reliably reduces appetite' framing.Safety Consideration
Sincalide's approved diagnostic use, dosing, and any product-labeled adverse effects belong to the Sincalide/Kinevac product and must not be presented as native CCK safety information.Safety Consideration
This review found no controlled human administration study of CCK-58 specifically. CCK-58's human efficacy/safety profile should be treated as unestablished, not inferred from CCK-33 or CCK-8.
Research Areas Being Studied
Research areas discussed on this page reflect the Gastrointestinal / Gut-Hormone Signaling category and the sources cited below.
Findings Reported in Studies
Educational summary only — reported in cited studies, not a claim of proven benefit.
- Untangling the Effects of Hunger, Anxiety, and Nausea on Energy Intake During Intravenous Cholecystokinin Octapeptide (CCK-8) Infusion (1998):
- Satiety Effects of a Physiological Dose of Cholecystokinin in Humans (1995):
- Satiety Effects of Cholecystokinin in Humans (1994):
- Effects of a Physiological Dose of Cholecystokinin on Food Intake and Postprandial Satiation in Man (1993):
- C-Terminal Octapeptide of Cholecystokinin Decreases Food Intake in Obese Men (1982):
- Cholecystokinin Octapeptide Decreases Intake of Solid Food in Man (1982):
Study Tables by Evidence Type
Human Studies & Clinical Data
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| Untangling the Effects of Hunger, Anxiety, and Nausea on Energy Intake During Intravenous Cholecystokinin Octapeptide (CCK-8) Infusion | 1998 | 15 male subjects | IV CCK-8 (20-minute infusion) reduced energy intake, but the effect was statistically confounded with concurrent nausea and anxiety ratings, raising the possibility some or all of the apparent satiety effect reflects an aversive response rather than a pure satiety mechanism. | A genuine confound -- must not present CCK-8's food-intake reduction as unambiguously a satiety effect without this caveat. | |
| Satiety Effects of a Physiological Dose of Cholecystokinin in Humans | 1995 | IV native CCK-33 at a physiological dose reduced ad-libitum food intake in human subjects. | |||
| Satiety Effects of Cholecystokinin in Humans | 1994 | 32 subjects, lean and obese | IV native CCK-33 at physiological-range doses significantly reduced hunger and 'wish to eat' ratings vs. saline. | ||
| Effects of a Physiological Dose of Cholecystokinin on Food Intake and Postprandial Satiation in Man | 1993 | 9 lean + 9 obese subjects | Food intake (486±52 g) was slightly, but not significantly decreased (553±55 g after saline), and hunger and fullness feelings after eating were unaffected, in both groups. CCK-33 infusion to plasma levels comparable to a fatty meal does not have a major effect on food intake and postprandial hunger feelings. | Genuine negative/null finding -- must NOT be cited as positive efficacy support for CCK-33. | |
| C-Terminal Octapeptide of Cholecystokinin Decreases Food Intake in Obese Men | 1982 | 8 obese men | 6 of 8 obese men ate significantly less during IV CCK-8 infusion vs. saline and stopped eating sooner; 2 of 8 did not respond. | ||
| Cholecystokinin Octapeptide Decreases Intake of Solid Food in Man | 1982 | 16 young non-obese subjects | Dose-dependent reduction in sandwiches eaten (50% and 17% fewer at two CCK-8 doses) vs. saline given IV CCK-8. |
Animal / Cell / Preclinical Data
No Animal / Cell / Preclinical Data Listed Yet
This section will be updated as sources are added.
Regulatory Documents & Official Trial Registries
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| FDA Label / DailyMed Record for KINEVAC (Sincalide) Injection | 1976 | Sincalide (Kinevac), a synthetically manufactured C-terminal CCK octapeptide with a sequence identical to native CCK-8 (including the biologically essential sulfated tyrosine), is FDA-approved (since 1976) to stimulate gallbladder contraction for diagnostic imaging and to stimulate pancreatic secretion (combined with secretin) prior to duodenal aspiration for pancreatic function testing. | Sincalide's approved diagnostic use, dosing, and regulatory status are product-specific and must NOT be used to inflate native CCK-33/CCK-58's own evidence grade, nor placed in native Cholecystokinin's unrestricted alias list. | No source link available |
Anecdotal Reported Patterns — Not Medical Advice
Anecdotal Reported Patterns — Not Medical Advice
Reported dosing patterns are included for educational context only. They are self-reported, unverified, not medical advice, and not instructions for human use. Community-submitted patterns are not yet available in this Phase 1 prototype; this section is a placeholder reserved for moderated, aggregated community data.
Lab Markers to Discuss With a Clinician
Educational topics only — not self-monitoring instructions.
FAQ
Disclaimer
Educational information only. This page summarizes published human research on cholecystokinin and does not constitute medical advice, a treatment recommendation, or dosing guidance for any CCK-related substance.
Educational use only. This content is provided for informational and research-summary purposes only. It is not medical advice, not a treatment recommendation, not a dosing guide, and not a substitute for care from a licensed medical professional. Nothing here is intended to diagnose, treat, cure, prevent, or mitigate disease. Reported dosing patterns, when shown elsewhere on the site, must be labeled either as Study / Trial Dosing or Anecdotal Reported Patterns — Not Medical Advice. Community reports are self-reported, unverified, and not scientific proof.
Community-reported experiences, once enabled, must be displayed only as moderated, anonymized, or aggregated data. They are anecdotal, self-reported, unverified, and should never be presented as proof of safety, efficacy, or expected results.
Content status: Published. Last updated 2026-08-26.
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