While all of the effects described above certainly occur in response to oxytocin, doubt has recently been cast on its necessity in parturition and maternal behavior. Mice that are unable to secrete oxytocin due to targeted disruptions of the oxytocin gene will mate, deliver their pups without apparent difficulty and display normal maternal behavior. However, they do show deficits in milk ejection and have subtle derangements in social behavior. It may be best to view oxytocin as a major facilitator of parturition and maternal behavior rather than a necessary component of these processes.


Melanotan II was originally developed as a treatment for sexual dysfunction. However, this was abandoned when the metabolite bremelanotide was developed instead for treatment of haemorrhagic shock. Melanotan II is usually injected subcutaneously for the purposes of sunless tanning, appetite suppression, inducing sexual desire and penile erection and other conditions such as rosacea and fibromyalgia. There are also dose forms available for nasal administration. The therapeutic dose is considered to be 0.01 mg/kg.
The short half-life (<2h)[16] of 5-HTP may inherently limit the therapeutic potential of 5-HTP,[17] as the systemic 5-HTP exposure levels will fluctuate substantially, even with relatively frequent dosing. Such exposure fluctuations are usually associated with increased adverse event burden, resulting from Cmax drug spikes, and decreased clinical efficacy resulting from sub-therapeutic exposure for large parts of the day. It has been proposed that 5-HTP dosage forms achieving prolonged delivery would be more effective,[17] as is generally the situation with short-acting active pharmaceutical ingredients.[18]
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