The evidence for this is disputed, with 9 reported cases of torsades in 30 years and all of those having received doses in excess of 5 mg. QT prolongation is a dose-related effect, and it appears that droperidol is not a significant risk in low doses. A study in 2015 showed that droperidol is relatively safe and effective for the management of violent and aggressive
adult patients in hospital emergency departments in doses of 10mg and above and that there was no increased risk of QT prolongation and torsades de pointes. Side effects
Dysphoria, sedation, hypotension resulting from peripheral alpha adrenoceptor blockade, prolongation of QT interval which can lead to torsades de pointes, and extrapyramidal side effects such as dystonic reactions/neuroleptic malignant syndrome. Chemistry
Droperidol is synthesized from 1-benzyl-3-carbethoxypiperidin-4-one,
which is reacted with o-phenylenediamine. Evidently, the first derivative that is formed under the reaction conditions, 1,5-benzodiazepine, rearranges into 1-(1-benzyl-1,2,3,6-tetrahydro-4-piridyl)-2-benzymidazolone. Debenzylation of the resulting product with hydrogen over a palladium catalyst, and subsequent alkylation of this using 4-chloro-4-fluorobutyrophenone yields droperidol. C. Janssen, NV Res. Lab., GB 989755  (1962). Janssen, P. A. J.; 1963, Belgian Patent BE 626307 . F.J. Gardocki, J. Janssen, U.S. Patent 3,141,823 (1964). P.A.J. Janssen, U.S. Patent 3,161,645 (1964). (See pimozide article for proposed mechanism of intramolecular rearrangement.) References
Further reading
Scuderi PE (2003). "Droperidol: Many questions, few answers". Anesthesiology. 98 (2): 289–90. doi:10.1097/00000542-200302000-00002. PMID 12552182. Lischke V, Behne M, Doelken P, Schledt U, Probst S, Vettermann J. Droperidol causes a dose-dependent prolongation of the QT interval.
Pelvis justo major (also called "Giant Pelvis") is a rare condition of the adult female pelvis where the pelvis flairs above the Iliopectineal line. It is 1.5 or more times larger than an average pelvis in every direction and is at least 42 cm (16.5 inches) biiliac width. Even though this condition is classified as a congenital abnormality, it is not a medical disease or abnormality of the pelvis (as the pelvis is a true gynecoid shape, only larger). Women with this condition, at the time of delivery, may have a precipitous birth. There is virtually no resistance of the huge pelvic opening to the size of a newborn so only the soft parts resist the birth. With a huge Justo Major Pelvis, there is no pelvic bone "molding" of the fetal head. With the average pelvic size (2/3 or less Justo Major size) the usual pelvic molding process slows the birth, resulting in a slow and gradual stretching of the vaginal opening for primiparous women. When a huge Justo Major Pelvis allows such an extremely rapid vaginal birth, there can be tears of the perineal soft tissues. At the time of delivery the strong uterine contractions and maternal bearing down almost instantly overwhelm the integrity of a tightened and previously unstretched vaginal orifice. This is often the case if such women have not previously practiced vaginal stretching to the degree that allows such an instant birthing, especially so for a primiparous woman.