Ways to Administer
The way a peptide enters the body matters as much as the dose. The right route depends on the compound, its stability, and the research goal. Here is every route at a glance, plus a complete guide to injection equipment — syringes, pens, sizes, and standards.
Oral
Taken by mouth as capsules, tablets, or liquids. Convenient and pain-free, but most peptides are broken down by stomach acid and digestive enzymes — bioavailability is often low. Workable for compounds that survive digestion, like MK-677 or NMN.
Injection
The workhorse route for research peptides. Injecting under the skin or into a muscle bypasses digestion and delivers the compound straight into the bloodstream. It offers the highest, most predictable bioavailability, at the cost of requiring reconstitution, sterile technique, and sharps handling.
Nasal
Sprayed into the nasal cavity and absorbed through the mucous membranes. This route offers fast uptake and a direct path to the brain via the olfactory nerve. Volume is limited and dose consistency can vary, but it works well for compounds like Semax.
Topical
Applied to the skin as a serum, cream, or patch. This route is useful for localized effects such as skin repair or wound healing. The limitation is penetration — most peptides cannot cross the skin barrier in meaningful amounts, though GHK-Cu is a notable exception.
Injection, in depth
Injection is the standard for peptide research because it delivers the compound with maximum, predictable bioavailability. Two tools dominate: syringes and pens.
Syringes
The classic tool. After reconstitution, the dose is drawn into an insulin syringe marked in units.
Insulin syringes follow a universal standard: 100 units per milliliter (1 mL). That means 100 units on the barrel equals exactly 1 mL — and every 10 units is 0.1 mL. Peptide dosing uses this same scale, so the calculator always speaks in units you can find on a real syringe.
Common sizes
Three capacities cover nearly every peptide dose:
Very small, precise doses
The most versatile mid-range choice
Larger volumes or higher concentrations
Insulin needles are short and ultra-fine — usually 29G to 31G (the higher the gauge, the thinner the needle) and 5/16″ to 1/2″ long. These are ideal for subcutaneous delivery and cause minimal tissue trauma.
Pens
A modern alternative. Pens are pre-filled or reusable devices that deliver an exact dose per click — no drawing, no measuring.
Each click delivers a set amount, typically 250 mcg, 500 mcg, or 1 mg. Dial to your target dose — 4 clicks at 250 mcg/click = 1,000 mcg. The calculator includes a pen mode with the same logic.
Pens are easier to learn, more consistent, and reduce the risk of drawing the wrong volume. The catch: you are limited to the pen’s increment and to peptides that come in pen form.
Subcutaneous vs intramuscular
Two injection depths. Most peptide research uses subcutaneous.
Subcutaneous (SubQ)
Injected into the fat layer just beneath the skin, usually the abdomen or thigh. Use a short, fine needle (29G–31G, 5/16″). Slow, steady absorption.
Intramuscular (IM)
Injected deep into a muscle, usually the thigh or deltoid. Use a longer needle (25G–27G, 1″). Faster absorption, slightly more discomfort.
Syringe or pen?
Both deliver the same peptide — the difference is workflow.
Remember
Always follow the label and instructions that ship with your compound. Need a refresher on reconstitution? The first-time guide covers it step by step.
Ready to calculate your dose?
Open the calculator, set your vial and solvent, and see the exact units or clicks.
Open the Calculator