One IU of oxytocin is the equivalent of about 2 μg or mcg of pure peptide.

Injection: Clinical doses of oxytocin are given by injection either into a muscle or into a vein to cause contraction of the uterus.
Very small amounts (< 1%) do appear to enter the central nervous system in humans when peripherally administered.
The compound has a half life of typically about 3 minutes in the blood when given intravenously.
Intravenous administration requires 40 minutes to reach a steady-state concentration and achieve maximum uterine contraction response.

Buccal: Oxytocin was delivered in buccal tablets, but this is not common practice any more.

Under the tongue: Oxytocin is poorly absorbed sublingually.

Nasal administration: Oxytocin is effectively distributed to the brain when administered intranasally via a nasal spray, after which it reliably crosses the blood–brain barrier and exhibits psychoactive effects in humans.
No serious adverse effects with short-term application of oxytocin with 18~40 IU (36–80 mcg) have been recorded.
Intranasal oxytocin has a central duration of at least 2.25 hours and as long as 4 hours.

Oral: Oxytocin is destroyed in the gastrointestinal tract, so it is not active orally.
One IU of oxytocin is the equivalent of about 2 μg or mcg of pure peptide.
Injection: Clinical doses of oxytocin are given by injection either into a muscle or into a vein to cause contraction of the uterus. Very small amounts (< 1%) do appear to enter the central nervous system in humans when peripherally administered. The compound has a half life of typically about 3 minutes in the blood when given intravenously. Intravenous administration requires 40 minutes to reach a steady-state concentration and achieve maximum uterine contraction response.
Buccal: Oxytocin was delivered in buccal tablets, but this is not common practice any more.
Under the tongue: Oxytocin is poorly absorbed sublingually.
Nasal administration: Oxytocin is effectively distributed to the brain when administered intranasally via a nasal spray, after which it reliably crosses the blood–brain barrier and exhibits psychoactive effects in humans. No serious adverse effects with short-term application of oxytocin with 18~40 IU (36–80 mcg) have been recorded. Intranasal oxytocin has a central duration of at least 2.25 hours and as long as 4 hours.
Oral: Oxytocin is destroyed in the gastrointestinal tract, so it is not active orally.
Oxytocin (medication)