The DDAVP/factor VIII tale as viewed from Milan (and Malmö) is not one of serendipity, it is the outcome of a long-lasting, tenacious pursuit of a pharmacological treatment of hemophilia. The tale also witnesses how knowledge and inspiration are transmitted from mentors to pupils, in full realization of the Hippocratic oath! In 1964 I spent 3 months learning the first rudiments of blood coagulation at St Thomas Hospital, London with Ilsley Ingram, working in the old Louis Jenner Laboratories overlooking the Thames, Big Ben and the Houses of Parliament. Ilsley is a fascinating man, with a lot of interests beside blood coagulation, being a poet, a wild orchid specialist and an archeologist (Fig. 1). I was much enthralled by his efforts to find pharmacological alternatives to plasma-derived factor (F)VIII for the treatment of hemophilia. Following earlier work of the famous physiologist Cannon on the hypercoagulability of blood induced by stress, Ingram had shown in the early 1960s that in normal individuals the infusion of epinephrine induced a transient 2- to 3-fold increase of FVIII and, most importantly, that such an increase could also be elicited in patients with mild hemophilia [1Ingram G.I.C. Increase in antihemophilic globulin activity following infusion of adrenaline.J Physiol. 1961; 156: 217-24Crossref PubMed Scopus (0) Google Scholar]. At the same time Charley Rizza had shown that strenuous physical exercise induced a similar increase in normal individuals and mild hemophiliacs [2Rizza C.R. Effect of exercise on the levels of antihemophilic globulin in human blood.J Physiol. 1961; 156: 128-35Crossref PubMed Scopus (67) Google Scholar], an effect that was later shown to be due to β-adrenergic receptor stimulation. Even though this pioneer work carried out in Britain showed that it is possible to transiently increase FVIII in patients with measurable levels of this moiety, it was obviously unconceivable to use clinically epinephrine infusion or strenuous exercise to establish whether or not the related FVIII increase is paralleled by greater hemostatic competence in patients with moderate and mild hemophilia and von Willebrand disease (VWD). Upon my return to Italy in 1965, I implemented the knowledge that I had acquired in London and in Oxford (with Gwyn MacFarlane, Rosemary Biggs and Judith Pool, who had just described the preparation of cryoprecipitate) to help my colleagues at the Blood Bank to prepare cryoprecipitate and thereby start the clinical activities of the Angelo Bianchi Bonomi Hemophilia and Thrombosis Center. With my former colleagues Zaverio Ruggeri, Francesco Pareti and Anna Capitanio, a number of surgical operations that had not been previously possible were carried out. It was alarming, though, to notice that many patients developed hepatitis with jaundice and an increase in serum transaminases. This prompted us to continue the search, initially pursued by Ilsley Ingram and Charley Rizza, of a pharmacological alternative to plasma FVIII, devoid of the unacceptable side-effects of epinephrine and of the inconvenience of strenuous muscular exercise. We pursued several approaches, particularly those based upon drugs that acted through the elevation of cyclic AMP as second messenger. Incidentally, it is remarkable that the mechanism of action of DDAVP, that had long remained obscure despite 25 years of clinical applications, was recently shown to be mediated by the increase of cyclic AMP in endothelial cells (see the accompanying review article of Kaufmann and Vischer [3Kaufmann J.E. Vischer U.M. Cellular mechanisms of the hemostatic effects of desmopressin (DDAVP).J Thromb Haemost. 2003; 1: 682-9Abstract Full Text Full Text PDF PubMed Scopus (185) Google Scholar]). In 1970 we found that lysine vasopressin (LVP), a synthetic derivative of the naturally occurring antidiuretic hormone arginine vasopressin, was among the most potent FVIII raising agents, superior to insulin, arginine, exogenous cyclic AMP, dibutiryl cyclic AMP, theophylline and others (Fig. 2). Unfortunately, the side-effects of LVP were different to, but no less unpleasant than, those of epinephrine. In July 1971, I was invited to speak about the effect on blood coagulation of LVP and other drugs or procedures at a Symposium on ‘Stress, thrombosis and atheromatosis’, during the Second Congress of the International Society on Thrombosis and Haemostasis, organized in Oslo by Paul Owren. The title of my talk was ‘Effect on blood coagulation of stressful stimuli’. Another speaker at that meeting was a young and dashing John Cash, who spoke on ‘Platelets, fibrinolysis and stress’[4Cash J. Platelets, fibrinolysis and stress.Thrombosis. Risks Factors and Diagnostic Approaches. Schattauer Verlag, 1972: 93-104Google Scholar]. My findings on the effect of LVP on FVIII and on its independence from β-adrenergic stimulation were published in full in 1972 in the Congress Proceedings [5Mannucci P.M. Gagnatelli G. D'Alonzo R. Stress and blood coagulation.Thrombosis: Risks Factors and Diagnostic Approaches. Schattauer Verlag, 1972: 105-13Google Scholar]. Subsequently I closely followed the literature, hoping to find derivatives of vasopressin or other compounds devoid of the effects on V1 receptors, which caused vasoconstriction, hypertension and severe abdominal cramps. The first time that I heard about DDAVP and about its lack of systemic side-effects was by reading an article published in 1972 in Acta Medica Scandinavica by two Swedish endocrinologists [6Andersson K.E. Arner B. Effects of DDAVP, a synthetic analogue of vasopressin, in patients with cranial diabetes insipidus.Acta Med Scand. 1972; 192: 21-7Crossref PubMed Google Scholar]. I wrote to them and they advised me to contact Jan Mulder of Ferring (Malmö, Sweden) to see whether I could obtain from him a supply of the compound for my experiments in humans. At that time, restrictions and regulations for the investigation of new drugs or for new indications of a licensed one were much looser than they are now. Ex vivo experiments could be done relatively easily in normal volunteers, who often were the investigators themselves. I remember Ilsley Ingram showing a scar over a forearm vein and telling me that repeated venipunctures and self-infusions of epinephrine had made painless the puncture of the vein underlying the scar. As a good disciple I was soon proud to have a similarly painless vein, after so many infusions of DDAVP, LVP and at least a dozen other compounds! Going back to Jan Mulder, he came to Milan in late spring 1973 and my colleagues and I showed him the work done with various FVIII-raising drugs. He informed us that John Cash was investigating the effects of DDAVP on fibrinolysis and FVIII. I was not surprised, because our research paths had run so closely parallel in the previous few years! However, I thought that my greater experience with FVIII and having several patients with mild hemophilia ready to try the new drug were on my side in the scientific competition. To make a long story short, on August 1st 1973 I infused myself with 0.5 µg kg-1 of DDAVP, and FVIII jumped from 106 to 336% with no side-effects. Needless to say, Zaverio Ruggeri, Francesco Pareti and Anna Capitanio, who were prudently on vacation at the time of my first self-infusion of DDAVP, were not spared one, as soon as they came back! At this point Malmö and Inge Marie Nilsson came on the stage. Knowing about my studies, Inge Marie had told me that she had facilities for doing ex vivo pharmacological studies due to the availability a group of firemen from the Malmö's municipality who were available and ‘eager’ (sic) to make available their arms and blood for such studies. The opportunity was great, because to tell you the truth my colleagues in Milan had become quite deaf to my proposals to be infused with drugs not entirely devoid of side-effects and to undergo repeated venipunctures, painless or not! In September 1973 I went to Malmö for one month and I brought with me several vials of desmopressin that curiously enough were manufactured in Malmö itself. Inge Marie Nilsson did not know that a pharmaceutical company was manufacturing DDAVP at her doorstep but, astute as she was, she understood immediately the great potential of the drug. In only one month we did the experiments that confirmed that DDAVP consistently increased FVIII levels 3- to 4-fold over baseline, and demonstrated that the effect was not mediated by epinephrine, because it was not blocked by the concomitant infusion of the β-blocker propranolol. We also demonstrated that the V2 receptor subtype expressed in the kidney collecting duct mediating the antidiuretic effect of DDAVP was not involved in the FVIII raising effect, because the latter was present in a patient who had undergone bilateral nephrectomy. The experiments were completed when I left Malmö in October 1973 but because we were evaluating other vasoactive compounds that eventually proved to be of no clinical usefulness, it took a long time before the full paper describing the effect in humans of DDAVP and other vasoactive drugs on FVIII and fibrinolysis was submitted to the British Journal of Haematology (September 1974) to be published in 1975 [7Mannucci P.M. Aberg M. Nilsson I.M. Robertson B. Mechanism of plasminogen activator and factor VIII increase after vasoactive drugs.Br J Haematol. 1975; 30: 81-93Crossref PubMed Google Scholar]. Meanwhile, in the December 1973 issue of The Lancet Gader, da Costa and Cash published a short paper on the effect of DDAVP on fibrinolysis [8Gader A.M. Da Costa J. Cash J.D. A new vasopressin analogue and fibrinolysis.Lancet. 1973; ii: 1417-8Abstract Google Scholar] and in January 1974 they also reported the effect on FVIII at the Annual Meeting of the British Society for Haematology, published in abstract form in the British Journal of Haematolgy[9Cash J.D. Gader A.M. Da Costa J. The release of plasminogen activator and factor VIII to lysine vasopressin, arginine vasopressin, 1-desamino-8-d-arginine vasopressin, angiotensin and oxytocin in man.Br J Haematol. 1974; 27: 363-4PubMed Google Scholar]. The clinical demonstration of the hemostatic effectiveness of DDAVP in patients is a truly Milanese tale, definitely facilitated by our large and cooperative group of hemophiliacs. They were aware of the risk of hepatitis carried by blood derivatives, particularly since we reported in 1975 that they had abnormal liver function tests, albeit with little or no evidence of severe disease [10Mannucci P.M. Capitanio A. Del Ninno E. Colombo M. Pareti F. Ruggeri Z.M. Asymptomatic liver disease in haemophiliacs.J Clin Pathol. 1975; 28: 620-4Crossref PubMed Google Scholar]. Cognizant that there was no evidence that the rise in endogenous factor VIII elicited by DDAVP was hemostatically efficacious, it was with great caution that we started to treat patients with DDAVP, choosing dental extractions as the first model of clinical efficacy. We reasoned that any bleeding could be seen by direct inspection of the oral cavity with little risk for the patient, considering also that we could always resort to cryoprecipitate in case of failure. Because we were also concerned that the brisk albeit transient fibrinolysis enhancement induced by DDAVP could jeopardize the stability of the clot in the sockets, we chose to give concomitantly epsilon aminocaproic acid. The early results were very favorable: we learnt that the 3- to 4-fold DDAVP-induced increase of FVIII was sufficient to secure hemostasis provided baseline levels were at least 4–5%. We also learnt that most patients with moderate hemophilia (FVIII levels 1–5%) did not respond well enough to DDAVP to prevent excessive extraction bleeding or late rebleeding, and that antifibrinolysis was not strictly necessary even though it helped to reduce the number of infusions. After having accumulated sufficient confidence and experience with dental extractions we moved, not without trepidation, to major surgical procedures like tonsillectomy, cholecystectomy, hysterectomy and cholectomy, not only in patients with mild hemophilia A but also in those with VWD. Again, the clinical efficacy and the prevention of bleeding complications were satisfactory, provided the indication was evaluated carefully in each patient, considering variables such as the baseline levels of FVIII and of von Willebrand factor, the levels desired and attained after DDAVP infusion and the time needed to keep these factors at hemostatic levels. Water retention and hyponotremia did not prove to be frequent problems. At the end of 1976 I decided to submit to The Lancet a full manuscript on our clinical experience, cosigned by the members of the team who had collaborated with me in the painstaking search of a FVIII raising agent (Ruggeri, Pareti and Capitanio). The paper was accepted swiftly [11Mannucci P.M. Ruggeri Z.M. Pareti F.I. Capitanio A. 1-Deamino-8-d-arginine vasopressin: a new pharmacological approach to the management of haemophilia and von Willebrand's' disease.Lancet. 1977; i: 869-72Abstract Google Scholar] and was accompanied by an anonymous Editorial [12Anonymous.DDAVP in haemophilia.Lancet. 1977; i: 889-90Google Scholar] that I suspect was written by Ilsley Ingram. It generated a lot of interest and a lot of correspondence but it took some time before DDAVP was licenced for the indication in countries other than Italy. For instance, in the USA it was first evaluated in humans in 1982 [13Warrier A.I. Lusher J.M. DDAVP: a useful alternative to blood components in moderate hemophilia A and von Willebrand disease.J Pediatr. 1983; 102: 228-33Abstract Full Text PDF PubMed Google Scholar] but it was not licenced until 1984, perhaps because the innovative concept of a pharmacological treatment of hemophilia had to sink into the habits and mentality of the caregivers and because caution was duly exerted by the regulatory agency. In Italy, we were lucky enough to use the drug on a large scale in the late 1970s throughout the early 1980s, at a time when the AIDS epidemic started. Accordingly, the prevalence of HIV infection in Italian patients with mild hemophilia A was eventually much lower than in a group of Italian patients with mild hemophilia B, taken as comparison group by virtue of being unresponsive to DDAVP so they could only use plasma derived FIX (2% vs. 18%) [14Mannucci P.M. Ghirardini A. Desmopressin: twenty years after.Thromb Haemost. 1997; 78: 958Crossref PubMed Scopus (0) Google Scholar]. Another indirect comparison was done between Italian and US patients with mild hemophilia A, who did not use DDAVP on a large scale until 1985, at a time when concentrate heating halted most new infections: the prevalence of HIV in US mild hemophiliacs was much higher than that of Italian hemophiliacs [14Mannucci P.M. Ghirardini A. Desmopressin: twenty years after.Thromb Haemost. 1997; 78: 958Crossref PubMed Scopus (0) Google Scholar]. The impact of DDAVP in the prevalence of viral hepatitis was less marked and visible, perhaps because the widespread use of large pool coagulation factor concentrates since the early 1970s had already infected with the hepatitis C virus practically all treated hemophiliacs, so that the sparing effect of DDAVP did not significantly change the dimension of the epidemics. In conclusion, for me the tale of DDAVP is the most significant event of my life of clinical scientist, a tribute to my mentor Ilsley Ingram and to some colleagues of mine, such as Anna Capitanio who died so tragically, or Zaverio Ruggeri, who left the native nest to make many more important contributions in the field of hemostasis and thrombosis.