Libido Peptides – Research Compounds

Mechanisms

Two distinct pathways, not two versions of the same thing

HCG (human chorionic gonadotropin) is a glycoprotein hormone analogue studied for its action on the LH/CG receptor, and is referenced in endocrine and testicular-function research, frequently in the context of hormone-support protocols. Melanotan II is a melanocortin peptide studied for α-MSH signalling; while best known for pigmentation research, its libido and mood-pathway applications are a documented and separate research use, generally investigated at 250–500 mcg, 2–3× weekly with evening timing preferred and lower doses often sufficient.

Purist Peptides research compounds in a laboratory setting

Study design

Research framing and availability

This is endocrine and neuroendocrine research, not hormone therapy, and no medical claim is made for either compound. Both are supplied strictly for laboratory use. Please note HCG availability is limited and the category may not always show full stock. Melanotan II protocols also warrant attention to the transient flushing and nausea responses documented on its product page, which is why evening administration and lower starting doses are standard in the literature.

The range

Compounds in this category

The compounds grouped here, each with the pathway it is studied for and the protocol shape most often used.

HCG research peptide vial by Purist Peptides

HCG

Gonadotropin analogue

A glycoprotein hormone analogue studied for LH/CG receptor activity, endocrine signalling and testicular function, commonly referenced in hormone-support research contexts. Stock is limited.

View HCG

Melanotan II

Melanocortin agonist

Also studied for pigmentation and photoprotection. A melanocortin peptide studied for α-MSH-related libido and mood pathways at 250–500 mcg, 2–3× weekly over 4–6 weeks, with evening dosing preferred

View Melanotan II

Selection

How to choose

Start from the research question, not the compound name.

If the research question is…	Start with
Hormonal and endocrine-axis research	HCG
Melanocortin and central-pathway research	Melanotan II
Pigmentation rather than libido endpoints	see Peptides for Skin, where Melanotan II also appears
Endocrine research alongside body composition	the Hormone Optimisation Stack pairs HCG with Retatrutide
Growth-hormone axis instead	Peptides for Lean Muscle

Pre-paired

Stacks built on this category

Two pathways studied in parallel, priced and packaged as one protocol.

Hormone Optimisation StackHCG + Retatrutide — endocrine axis alongside body composition.View the stack

Independent laboratory testing of Purist Peptides research compounds

Verified quality

Tested before it ships

Minimum 99% verified purity, independently third-party assayed each batch · documented protocol, dose-titration and tolerance guidance on each product page, including transient-response notes for Melanotan II · lyophilised, refrigerate 2–8 °C after reconstitution. See Quality Standards.

See Quality Standards & all COAs

Questions

Libido research FAQ

How do HCG and Melanotan II differ?

They act on unrelated systems. HCG is a gonadotropin analogue acting on the LH/CG receptor, studied in endocrine and testicular-function research. Melanotan II is a melanocortin peptide studied for α-MSH signalling in central libido and mood pathways.

Is Melanotan II only for pigmentation?

No. Pigmentation is its best-known research application, but libido and energy-pathway research through α-MSH signalling is a documented separate use, typically at lower doses of 250–500 mcg, 2–3× weekly with evening timing.

Is this hormone therapy?

No. Both compounds are supplied strictly for in-vitro research and laboratory use by qualified researchers. No therapeutic or medical claim is made, and endocrine research is simply one context in which they are studied.

Why is evening dosing preferred for Melanotan II?

Research protocols commonly use evening administration to reduce the transient flushing and nausea responses documented on the product page. Lower starting doses are also standard for the same reason.

Is HCG in stock?

HCG availability is limited and fluctuates. Current stock is shown on the product page; where unavailable, register interest so you are notified when a batch arrives.

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