Excessive dosage or long-term administration has been known to result in tetanicuterine contractions, uterine rupture, postpartum hemorrhage, and water intoxication, sometimes fatal. Oxytocin was added to the Institute for Safe Medication Practices's list of High Alert Medications in Acute Care Settings in 2012. The list includes medications that have a high risk for harm if administered incorrectly. During pregnancy, increased uterine motility has led to decreased heart rate, cardiac arrhythmia, seizures, brain damage, and death in the fetus or neonate. Use is linked to an increased risk of postpartum depression in the mother. Certain learning and memory functions are impaired by centrally administered oxytocin. Also, systemic oxytocin administration can impair memory retrieval in certain aversive memory tasks. However, oxytocin does seem to facilitate learning and memory specifically for social information. Healthy males administered intranasal oxytocin show improved memory for human faces, in particular happy faces.
Pharmacokinetics
Routes of administration
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 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 have been recorded. Intranasal oxytocin has a central duration of at least 2.25 hours and as long as 4 hours.
Its uterine-contracting properties were discovered by British pharmacologist Sir Henry Hallett Dale in 1906. Oxytocin's milk ejection property was described by Ott and Scott in 1910 and by Schafer and Mackenzie in 1911. Oxytocin became the first polypeptide hormone to be sequenced or synthesized. Du Vigneaud was awarded the Nobel Prize in 1955 for his work.
Etymology
The word "oxytocin" was coined from the term oxytocic. Greek ὀξύς, oxys, and τόκος, tokos, meaning "quick birth").
Society and culture
Counterfeits
Oxytocin is marketed as a pheromone. Oxytocin in spray form is sold under the brands Attrakt and Connekt. It is not absorbed into the skin when used topically, but it may be inhaled in a manner similar to perfume applied to skin. Oxytocin sprays for insufflation are also sold, but often with little or no oxytocin at all. In African countries, some oxytocin products were found to be counterfeit medications.
Research
The trust-inducing property of oxytocin might help those with social anxiety and depression, anxiety, fear, and social dysfunctions, such as generalized anxiety disorder, post-traumatic stress disorder, and social anxiety disorder, as well as autism and schizophrenia, among others. However, in one meta-analysis only autism spectrum disorder showed a significant combined effect size. People using oxytocin show improved recognition for positive social cues over threatening social cues and improved recognition of fear.
Autism: Oxytocin may play a role in autism and may be an effective treatment for autism's repetitive and affiliative behaviors.
Relationship counseling: The use of oxytocin in relationship counseling for well-being has been suggested.
