Oxytocin (Love Hormone)

Oxytocin Chemical Bond Structure

Oxytocin Chemical Bond Structure

What is Oxytocin

Oxytocin, which is famously known as the ‘love hormone’ or the ‘trust hormone’ is an endogenous hormone that is naturally secreted by the supraoptic and the paraventricular nucleus of the hypothalamus. After its secretion, it is stored in the posterior pituitary glands. This so-called “love hormone” plays a very important role in childbirth, pregnancy, lactation, emotional bonding and social relations. Oxytocin works on pregnant women by stimulating the contraction of the smooth muscles in the uterus which is usually an indication that it is the end of the pregnancy and the beginning of childbirth. After the child delivery, oxytocin stimulates the production of a mother’s milk by activating the alveoli and enabling milk let-down which facilitates the whole process of lactation. There are speculations that in addition to these two processes, oxytocin also improves and strengthens the emotional bonds between a mother and her child. This hormone has been linked to mating and some parenting characteristics. Oxytocin is naturally produced in the body during sexual interactions and sexual intercourse in both men and women and for this reason, it is believed that this hormone is related to sexual and emotional bonding between two people. Numerous controlled studies have been carried out on the effects of this hormone on mental conditions like autism and its role or relationship in the developmental impairment of the brain that is associated with this condition.

Oxytocin has been around for a relatively long time, but they have never proved to be more effective when compared to the nasal spray form of this hormone. Injection products of this hormone have also been used, in fact, for the longest time but they have never made a breakthrough in the clinical markets maybe because self-injections have always been perceived as painful and very risky. Ever since the Oxytocin nasal sprays were introduced, many other products have followed suit but none of them have been adopted or preferred like the nasal spray forms. The nasal sprays of Oxytocin have been widely prescribed by physicians and used by patients not only because they are safe, simple and easy to use, but also because their effect can last for a whole day, which is far much longer than a single injection can. Nasal spray forms of Oxytocin also allow the hormone to travel actively and directly from the blood stream into the brain, which further assures its reliability.

Oxytocin can be clinically used to induce labor, to strengthen uterine contractions and to control post-partum bleeding in maternal women. In the United States, the use of oxytocin for managing clinical conditions was approved by the Federation of Drugs Association in 1962. However, intranasal formulations that can be used to activate milk let down are no longer manufactured.

The Mechanism of Action of Oxytocin

The synthetic form of Oxytocin showcases the same pharmacological characteristics as the endogenously produced oxytocin. These responses are determined by dilation, cervical parity, and the duration of labor in cases of labor stimulation. Oxytocin increases the permeability of the uterine myofibrils to sodium which indirectly stimulates the contraction of the smooth muscles of the uterus. Labour responses are very crucial to childbirth and child delivery so the uterus responds more actively and readily to Oxytocin in the presence of very high concentrations of estrogen and with an increasing duration of pregnancy. The levels of Oxytocin in pregnant women increases gradually for about 20 to 30 weeks into the pregnancy, then it goes through a plateau phase after 34 weeks until the end of the pregnancy when the woman’s sensitivity to oxytocin sharply increases. Women in labor are very sensitive to oxytocin when compared to women who are pregnant but not in labor and this is a very big advantage because it solicits uterine contractions. Oxytocin increases the frequency and the amplitude of uterine contractions which consequently inhibits the flow of blood to the uterus and leads to a decrease in cervical activities which causes dilation and effacement of the crevice thus facilitating the whole process of childbirth and child delivery.

oxytocin nasal spray structure

Oxytocin Structure

As for lactation, oxytocin leads to the contraction of the myoepithelial cells that surround the alveolar ducts of the breast. This action induces milk let-down from the alveolar channels into the larger breast sinuses which in turn facilitates the ejection of milk from the breasts. Oxytocin has no galactopoietic properties but when it is not present, the milk ejection reflex and the production of milk fails.
Oxytocin often leads to the dilation of the vascular smooth muscles which subsequently increases the flow of blood through the renal artery, cerebral arteries, and the coronary arteries. This action does not affect the pressure of blood in the body, but with the administration of very high doses or higher concentrations in solutions, the body’s blood pressure can be slightly decreased. This slight fall in the body’s blood pressure can lead to a reflex tachycardia or a slight increase in blood pressure which will ultimately be followed by another decrease in blood pressure.
Various studies that have been conducted on oxytocin have demonstrated some antidiuretic effects of this hormone but these effects are very minimal. However, if this hormone is administered concurrently with an excessive volume of an electrolyte free sodium solution at a rapid rate, its antidiuretic effects can be magnified. This process can result in severe water poisoning so it should be avoided completely.
Men generally produce lower levels of oxytocin when compared to women. Studies done on men in monogamous relationships have shown that this hormone can contribute to loyalty and fidelity by enhancing the female partner’s attractiveness when compared to other women. It has not been clearly established how this hormone works to achieve this but more research is being conducted. Researchers have very many theories on the effects of oxytocin on the human social behavior. Particularly, scientists argue that most hormones do not have the ability to influence behavior directly, instead, they affect the way human beings think. In the case of Oxytocin, there are suggestions that its anxiolytic properties are responsible for reducing anxiety which in turn prompts human beings to get close and stay close to a special someone. Oxytocin allows the brain to pay more attention to subtle cues and it also enables the brain to analyze social information at a higher capacity than during normal situations.

The Pharmacokinetics of Oxytocin

Oxytocin can be administered through a nasal inhalation and a parenteral injection. After a parenteral injection, this hormone attains steady levels in the plasma in about 40 minutes and it has a half-life of around 1-6 minutes. In pregnant women, this drug is usually distributed throughout the extracellular fluid with minimal amounts being passed on to the fetus. Oxytocinase is one of the few glycoprotein-amino peptides that has the ability to degrade oxytocin. It is usually produced at the onset of pregnancy then its levels are standardized and maintained in the plasma. The activity of this enzyme increases gradually until the time of birth when there is a sharp increase in Oxytocin. It is then metabolized when the effects of Oxytocin are desired in the uterus, the plasma, and the placenta. After child delivery, the activities of this enzyme gradually decline until it is excreted from the system. Oxytocinase most probably originates from the uterus and its main function is to check and regulate the amount of oxytocin in the uterus of pregnant women. There is very little to no degeneration of oxytocin in men and women who are not pregnant. Oxytocin undergoes metabolisis in the lactating mammary glands and it can be distributed into breast milk. After its metabolisis, it is rapidly removed from the plasma through the kidneys and the liver, a very small amount of this hormone is excreted through the urine.

Route-specific Pharmacokinetics of Oxytocin

Oral route administration. Chymotrypsin, which is always present in the GI tract immediately destroys oxytocin on interaction which renders any oral administration ineffective, oxytocin is therefore never administered orally.
Intravenous administration. When oxytocin is administered through an intravenous infusion, it solicits its effects on a woman’s uterine walls almost immediately and these effects can subside in about an hour, so this method is usually preferred when managing conditions that require fast and emergency responses.

Intramuscular route administration. When oxytocin is administered through an intramuscular injection, the uterus can respond in about three to five minutes. And this response will subside in about 2-3 hours.

Topical Route/ intranasal administration. Intranasal administration offers the most effective way of this medication’s administration because it is directly absorbed into the body and its effects last for longer than when using the other methods. After an intranasal administration, the myoepithelial tissues surrounding the breasts in women rapidly contract and these effects can be experienced within minutes. That is why intranasal administrations are the most preferred as a method of inducing lactation in mothers after a child delivery.

Indications of Oxytocin

The latest studies on the effects of oxytocin on the brain have revealed that this hormone plays major roles in the body that are far beyond that of childbirth and lactation only. Oxytocin also plays a key role in the establishment of social behaviors and personal relationships. Oxytocin also affects the feelings of love, trust and caring. Due to its positive influences on socialization, oxytocin has been indicated for the management of various mental disorders that can include autism, social anxiety, and schizophrenia. Smaller-scale studies have established that sniffing this hormone can help people with a condition of autism to interpret and understand social cues at a more advanced level and at a higher capacity. Because of these effects, many physicians prescribe it for the management of mental disorders in children.

In men, oxytocin is primarily indicated for the treatment of delayed orgasms and it is used to induce post orgasmic penile detumescence. In women, it is used to induce milk let-down which facilitates breastfeeding of infants and it can also be used to intensify sexual arousals. Oxytocin can be used in a case of prolonged pregnancy or during an abortion because of its labor inducing action.

Contraindications and Precautions of Oxytocin

Endogenous oxytocin is always involved in the process of lactation and it is always used as a treatment solution in mothers who experience difficulties with breastfeeding and those who cannot naturally induce the process of milk let down after child delivery. It can be excreted through the breast milk but it is not expected to have any effects on a breastfeeding infant.
Parenteral administration of oxytocin should be conducted by a qualified physician and it should be executed in a setting that has adequate and intensive medical care equipment and surgical facilities. These should be readily available in case of any adverse reactions because negative reactions from this administration can be life threatening.
According to manufacturers, synthetic oxytocin should only be used when the induction of labor is unavoidably necessary and this should be for medical purposes only. Oxytocin should never be used for a selective induction of labor since there is very little evidence to clearly establish the risk-benefit ratio of this process. During the administration of oxytocin, the fetuses and the mother’s heart rates, uterine contractions, and the mother’s blood pressure should be monitored. Where possible, the mother’s inter-uterine pressure should also be monitored so that any negative effects can be avoided before they lead to tragic results and future complications. If any kind of hypersensitive reaction occurs, the administration of this medication should be discontinued immediately. Uterine contractions that are induced by Oxytocin will decrease steadily after the administration is discontinued.
Inducing labour using oxytocin should be avoided whenever there is any evidence of the following conditions: abnormal foetal bleeding, fetal distress, fetal prematurity, uterine prolapse, placental Previa, caphalopelvic disproportion, Vasa Previa, grand multiparity, cervical cancer, genital herpes, previous surgery of the uterus or cervix which includes more than two caesarian deliveries and any other condition that may prevent an obstetric emergency that may require a surgical operation. Using Oxytocin in any of these situations might pose a risk that may lead to unnecessary maternal and fetal distress.
Clinical studies on oxytocin have established that this hormone may possess some antidiuretic effects and using it for prolonged periods of time can increase its chances of showcasing its antidiuretic effect. Using oxytocin for extended periods of time or the administration of oxytocin in very large volumes with low sodium infusion fluids is strongly contraindicated especially in patients with a condition of eclampsia or patients with uterine atony. This is because the antidiuretic effects of oxytocin can lead to potential water intoxication because of hypertension which can result in very adverse effects on the body.

Interactions of Oxytocin

In a number of selected cases, oxytocin can be used in combination with other oxytocics for the sake of clinical purposes. It should, however, be noted that there is a very high risk of severe uterine hypertrophy with a possible cervical laceration or a uterine rupture.
The concurrent use of prostaglandin E2, dinoprostone and oxytocin is not considered safe, so it is highly contraindicated. After removing a vaginal dinoprostone insert, it is advisable that you avoid using any other oxytocic agent for a period of at least 30 minutes. Oxytocic products should be used sequentially and with strict supervision from a qualified medical care provider.

The concurrent use of oxytocin with general anesthetics or with epidural and other spinal anesthetics can lead to the development of adverse cardiovascular conditions especially in individuals with a history of pre-existing heart conditions. The administration of cyclopropane with or without oxytocin has revealed various negative implications that can include maternal sinus bradycardia, hypotension, increase in cardiac output and heart rates, abnormal atrioventricular rhythms and systemic venous returns, in addition, the administration of halothane can decrease the sensitivity and responsiveness of the uterus to oxytocin and in very high doses, it can render this hormone ineffective. This can greatly increase an individual’s risk of uterine bleeding. It has not been clearly established whether other halogenated anesthetics will react to oxytocin in this manner but more studies are being conducted in order to confirm their effects and come to solid conclusions.

The concurrent administration of prophylactic vasopressors with oxytocin can lead to severe and persistent hypertension, these two drugs exhibit a synergistic vaso-constrictive effect on blood vessels. So this should be totally avoided. The incidence and effects of such an interaction can be decreased if vasopressors are not administered prior to any oxytocin medications. This interaction can also include other sympathomimetics like ephedra and mahuang.
You should avoid any oxytocin medication if you are undergoing treatment using any of the following medications; All medicines used to manage blood pressure, all medicines used to induce sleep during surgery and any other medications that are used to contract the uterus.
This list does not describe all the possible interactions so you should remember to always provide your health service provider with a list of all the medications that you are currently on, this should include all herbs and non-herbs, dietary supplements, vitamins, drugs such as alcohol and cigarettes and any other illegal drugs.

Side Effects of Oxytocin

Some individuals can experience hypersensitive reactions to the effects of Oxytocin. These side effects can also be realized after the administration of excessive doses of this medication which can lead to increased hypertonic uterine contractions that can last for very long periods of time. This can result in a number of reactions that can include; excessive postpartum bleeding, cervical laceration, pelvic hematoma and rupturing of the uterus.

Some cardiovascular effects that can be experienced by maternal women include hypertension, premature ventricular contractions, and arrhythmia exacerbation. Effects on the fetus can include; PVC’s, bradycardia and other forms of arrhythmias.
Due to its antidiuretic effects, severe water intoxication can occur if oxytocin is administered in very high doses of about 40 – 50 milliunits per minute and for extended periods of time. The management of water intoxication can include supportive therapy or an immediate oxytocin cessation. Very large doses of oxytocin can lead to fetal death, permanent brain damage of the fetus or a permanent damage of its central nervous system. Other rare complications like bleeding of the conjunctiva, blurred vision, and pulmonary edema have also been associated with water intoxication that is as a result of oxytocin. The administration of oxytocin has also been associated with anaphylactoid reactions.

Oxytocin-induced labor has implications of increased incidences of neonatal hyperbilirubinemia which is about 1.6 times more likely to occur than under normal circumstances. This can lead to a condition of neonatal jaundice.
Nausea and vomiting are also some side effects that have been associated with oxytocin.
You should contact your health service provider or seek emergency healthcare services immediately in case you experience any negative reactions after the administration of this medicine.
Some individuals can experience allergic reactions like skin rashes, itching, hives, swelling of the tongue face or lips and irritation. Other side effects can include breathing problems, excessive or continuous vaginal bleeding and an unusual weight gain.

Side effects like headaches and vomiting are very common and they don’t usually require serious medical attention except when they persist to disturbing levels.

This list may not include all the possible side effects and adverse reactions but if you ever experience any signs of a negative reaction, you should contact your health care service provider immediately.
If you miss a dose, you should take it as soon as you remember about it. Store all your medicine in a cool dry place away from sunlight and away from the reach of children.


Oxytocin is commonly prescribed for the treatment of sexual arousal issues, delayed orgasms in men and post-orgasmic penile detumescence. The strength combination of this hormone available in our pharmacy is 50 IU/ml in a 10ml spray activator. All our solutions are compounded under strict guidelines of the USP 795 which efficiently assures their quality. We have a standard quality assurance process which further ensures that all the products we dispense are uniform, consistent and potent. For more information about this medication and its administration, feel free to contact us.

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