What does “pinning” mean?

“Pinning” is informal slang for administering a substance with a needle and syringe. In peptide discussions it almost always means a subcutaneous or intramuscular injection, as opposed to an oral, nasal, or topical route.

The term comes from community forums rather than clinical literature — it will not appear in a published study or on a product label. It describes only the act of injecting, and carries no information about what is being administered, at what dose, or for what purpose.

Related terms you will see alongside it

• Subq / sub-Q / SC — subcutaneous, into the fat layer beneath the skin. See What is subcutaneous administration?
• IM — intramuscular, into muscle tissue. See What is intramuscular administration?
• Slin pin — an insulin syringe, typically U-100, graduated in units rather than millilitres
• Gauge — needle thickness, where a higher gauge number means a thinner needle
• Recon / reconstitute — dissolving a freeze-dried powder into liquid before it can be drawn. See What does “reconstitution” mean?
• BAC water — bacteriostatic water, the diluent most often used for reconstitution

Why the route comes up so often

Most peptides are not orally active: stomach acid and digestive enzymes break the peptide bonds before absorption, which is why injection dominates the discussion. Why are most peptides not orally active? explains the mechanism.

A dose is expressed as a mass in milligrams or micrograms but drawn as a volume, and the two are linked by the concentration of the reconstituted vial. The reconstitution calculator converts between them.

Peptide Library documents this terminology for research literacy. Nothing here is instruction in injection technique, and none of it is medical advice.