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Pharmacokinetics is defined as the use of mathematical models to quantitate the time course of drug absorption and disposition in man and animals. This discipline is the branch of pharmacology that aims to describe, through mathematics, the interactions and physiological processes (i.e. absorption, distribution, metabolism and excretion ? the ADME process) that the drugs undergo after administration. When applied to a clinical situation, pharmacokinetics (PK) provides the clinician with important information on optimal drug dosages for each single patient. In the present thesis, the focus moved to the importance of classical PK and its applications, starting from the theory and use of compartmental analysis and at the end arriving to illustrate the more recent notions of this discipline, popPK and PBPK, which are the most innovative topics in the clinical and translational pharmacology field. The classical PK usually, translated clinically, is represented by quick studies which have a significant relevance in understanding ADME process of drugs with their desired, collateral or adverse effects. The population PK approach aims to investigate the influence of the interindividual variability in a target population of subjects, evaluating the populations characteristics that influence the fate of a drug after administration. The time required for the development of a popPK study applied to the clinical setting is much longer than a classical PK study. Three studies of classical clinical PK and one population PK study were included in this thesis. The first study concerned dexmedetomidine (DEX) and aimed to define the kinetic profile of this sedative following intravenous administration in a group of dairy calves, comparing its pharmacological and clinical effects with those of another a-2 agonist, xylazine, for minor surgical procedures. The second study was related to the simultaneous administration, as preanaesthetics, of a mixture of DEX and methadone, an analgesic with a remarkable sedative efficacy belonging to the class of opioid ?-agonists. The aim was to establish the pharmacokinetic profile of this co-administration in dogs by oral transmucosal route and compare it with the intramuscular kinetic profile of the same drugs combination. The third research addressed the species Panthera tigris. Since the literature concerning the non- domestic animals? PK is lacking and needy of new information, specifically, the objective was to compare the kinetic profile of a simultaneous administration of DEX and ketamine, an injectable anaesthetic antagonist of NMDA receptors, following IM administration for chemical restraint in two groups of tigers. The population PK study wanted to determine the popPK profile of cefazolin administered in a clinical setting for prophylactic purposes in 78 dogs, of different breed, age, weight, sex, body condition scores and health status, undergoing different surgical procedures. The ultimate goal was the definition of Clinical Breakpoints for this antimicrobial administered to the canine patient according to the guidelines of the Veterinary Committee on Antimicrobial Susceptibility Testing (VetCAST). Finally, during these three years of PhD program, another popPK work has been started. This study is in collaboration with the veterinary anaesthesia Operative Unit of the University of Padua, which requested our laboratory for performing propofol quantification. The aim was the definition of the kinetic population profile of propofol, administered for the induction and maintenance of general anaesthesia with modern TCI technique, in order to determine a popPK model that would be applicable to dog anaesthesiology. Until now, propofol quantification has been accomplished, but the final popPK model is still under investigation (for this reason data are not reported in the thesis). In conclusion, the use of appropriate pharmacokinetic modelling was important to perform different types of studies which helped to provide the veterinary pharmacological literature with innovative data with wide clinical implications.

Pyloric stenosis is rarely reported in horses (Bart et al 1980; Bezdecova et al. 2009). Congenital and acquired conditions have been described (Church et al 1986; Heidmann et al 2004; Laing et al. 1992; McGill et al. 1984) clinical suspicion is based on clinical findings while definitive diagnosis is reached by exploratory laparotomy and gastroscopy. The use of other diagnostic techniques has never been described. Two foals were admitted for recurrent abdominal pain. Clinical and ultrasonographic (US) examinations were performed. Foals underwent Computed Tomography (CT) of the abdomen, both native and Helical Hydro-CT. US revealed mild stomach distension, mild small bowel wall thickening; small intestine obstruction was suspected in both foals. Case 1, two-month old Thoroughbred filly 130 kg of weight: CT showed segmental concentric pylorus stenosis, at the pyloric duodenal junction level. Mild liquid distension of the pyloric antrum and mixed gas and fluid distension of the cranial duodenum. During necroscopy the pyloric antrum showed stenosis due to an inelastic constricting ring reducing the lumen of the pyloric canal. The glandular part presented mild acute catarrhal gastritis. Case 2, three-month old Italian Saddle colt 142 kg of weigh: CT showed small amount of intraluminal hyperattenuanting material within the gastric fundus and duodenum. Hydro-CT highlighted the presence of mild pylorus narrowing, mild distension and moderate mucosal irregularities of the pyloric antrum. An acquired pyloric stenosis secondary to chronic gastritis of unknown origin was suspected. Explorative laparotomy was performed; the antrum was mildly distended and the pylorus appeared narrowed and hard on palpation; gastrojejunostomy was performed. Ante-mortem diagnosis of pyloric stenosis in horses is challenging because aspecific clinical signs. Native CT allowed to investigate both the stomach and the small intestine and, in one case, outlined the presence of pylorus stenosis. In case 2, only Helical Hydro-CT allowed better evaluation of the pyloric thickness. CT and Helical Hydro-CT can be considered a useful diagnostic tool in foal with clinical suspicion of pyloric stenosis., International Journal of Health, Animal Science and Food Safety, V. 5, N. 1s (2018)

The intranasal (IN) route shows promise for chemical restraint given the large area offered for drugs absorption. The nasal turbinates increase nasal mucosa surface, which have a greater blood flow than muscle, brain and liver tissue . Aim of the study is to compare the clinical effects and sedation scores following either IN or intramuscular (IM) administration of dexmedetomidine-methadone in dogs. Twenty mixed-breed, client-owned, healthy dogs, undergoing soft tissue surgery or diagnostic procedures, were randomly allocated in two groups (n = 10) to receive dexmedetomidine (0.01 mg kg-1) together with methadone (0.4 mg kg-1) IN (IN-group) or IM (IM-group). Temperament was evaluated before premedication (1 = calm and friendly, 4 = very excitable or nervous) (Maddern et al. 2010). Heart rate (HR), respiratory frequency (fR), body temperature, and side effects were recorded before (T0) and 10 (T10), 20 (T20) and 30 (T30) minutes after premedication. Sedation was scored 3 times (every 10 minutes) after drugs administration using a descriptive sedation scale (0 = no sedation, 13 = extremely sedated). Induction was performed at T30 with titrate-to-effect propofol and the dosage was recorded. Student T-test was performed. Weight, age, temperament, body temperature and propofol dose were not different between groups. At each time point, excluding T0, IM-group showed a statistically lower HR and fRcompared to IN-group. No undesirable effects were observed in both groups. Sedation score in IM-group was significantlyhigher compared to IN-group at each time point. In conclusion, despite statistical differences, IN administration produces a satisfactory clinical sedation with more gradual hemodynamic effects compared to IM injection; this is probably due to a direct transport of drugs from cranial nerves (I-V) to brain with limited systemic absorption. However, the high variability recorded in sedation score between subjects in IN-group (min 1/13; max 13/13 at T30) probably arises from a variable drugs conveyance from nasal mucosae to target cell in CNS by IN administration., International Journal of Health, Animal Science and Food Safety, Vol 5, No 1s (2018)

In zoo practice, for physical examination or medical procedure in captive tigers, chemical immobilization is needed and ketamine (KET) in association with sedatives is an option frequently used (Clark-Price et al., 2015). Aims of the study is the assessment of the pharmacokinetics of KET and its main metabolite, norketamine (NORKET), after its intramuscular administration in combination with dexmedetomidine in tigers. Nineteen adult captive tigers, from different zoos, were scheduled for periodic physical examination or diagnostic procedures at the Milan University facilities. All animals were administered with a combination of KET at 2 mg/kg and dexmedetomidine at 10 µg/kg, given intramuscularly through blowpipe darts. If necessary, tigers where re-administered with variable doses of KET and dexmedetomidine or other drugs. When animals were sufficiently sedated, blood samples were collected every 5-10 min for the time tigers were safely approachable. Nine animals were assigned to standard protocol group (KET 2 mg/kg and dexmedetomidine 10 µg/kg) and ten animals to non-standard protocol group (tigers administered with different doses of KET, 2 – 2.5 mg/kg, and dexmedetomidine 10 – 30 µg/kg or with any other necessary drug, such as titrate-to-effect propofol and isoflurane, respectively for anaesthesia induction and maintenance). Ketamine and NORKET were extracted from plasma according to a validated HPLC-UV method (Zonca et al., 2012). For pharmacokinetic assessment, KET and NORKET concentrations were analysed with a noncompartmental approach (Phoenix® 7.0, Pharsight). Differences in the pharmacokinetic parameters between groups were statistically analysed (SPSS 25.0, SPSS Inc.). This is the first study that evaluates the pharmacokinetics of KET and NORKET in tigers. Due to the harmful attitude of these animals, samples collection was limited to the period of sedation, a short time for a complete pharmacokinetic evaluation. Nevertheless, we observed a favorable kinetic profile of KET and NORKET and, from a clinical point of view, all animals showed a good recovery, no adverse effects and a good level of sedation. Standard Protocol (mean ± s.d.) Non-Standard protocol (mean ± s.d.) Ketamine HL_Lambda_z min 77.62 ± 54.50 76.14 ± 67.32 Tmax min 27.78 ± 7.90 49.70 ± 29.64 Cmax ug/mL 0.63 ± 0.17 0.67 ± 0.19 AUClast min*ug/mL 23.84 ±6.40* 35.97 ± 12.84* AUMClast min*min*ug/mL 802.24 ± 331.03* 2054.97 ± 1018.88* MRTlast min 32.88 ± 5.71* 54.38 ± 19.71* Norketamine Tmax min 51.89 ± 8.95* 77.10 ± 24.41* Cmax ug/mL 0.24 ± 0.07 0.23 ± 0.09 AUClast min*ug/mL 7.30 ± 3.98 11.07 ± 5.46 AUMClast min*min*ug/mL 291.94 ± 227.01* 701.87 ± 424.80* MRTlast min 36.95 ± 7.32* 58.65 ± 19.58* HL_Lambda_z = Elimination Half-Life; Tmax = Time to Maximum concentration; Cmax = Maximum Concentration; AUClast = Area Under the Curve to the last concentration; AUMClast = Area under the first Moment Curve to the last concentration ;MRTlast = Mean Residence Time to the last concentration Tab.1: Pharmacokinetic parameters of ketamine and norketamine in nineteen adult captive tigers after intramuscular administration of 2 mg/kg of ketamine, with or without variation from the standard protocol, in combination with dexmedetomidine (with * are indicated results with p < 0.05)., International Journal of Health, Animal Science and Food Safety, V. 5, N. 1s (2018)

Oral transmucosal (OTM) delivery is a simple and painless method for sedative administration in veterinary medicine and allows a rapid absorption without a first-pass metabolism by the liver (Porters et al. 2014.). OTM is particularly useful in aggressive animals (Santos et al. 2010). The aim of this study is to evaluate the efficacy of the OTM route in dogs for sedative administration in comparison with intramuscular (IM) injection. 24 mix-bread dogs undergoing soft tissue surgery or diagnostic procedures were randomly divided in 4 groups (n = 6): two groups received OTM administration of dexmedetomidine (10 µg/kg-1) together with butorphanol (0.2 mg/kg-1, BTF-OTM group) or methadone (0.2mg/kg-1, MTD-OTM group); two groups received intramuscular (IM) administration of dexmedetomidine (5 µg/kg-1) together with butorphanol (0.2 m/kg-1, BTF-IM group) or methadone (0.2 mg/kg-1, MTD-IM). Heart rate (HR), respiratory rate (RR), sedation score (Gruney et al. 2009) and side effects were recorded 10 (T10), 20 (T20) and 30 (T30) minutes after premedication. Induction was performed at T30 with titrate-to-effect propofol administration and the dosage required was recorded. At each time point BTF-IM group showed a statistically lower HR compared to BTF-OTM; RR was statistically lower at T10 in MTD-OTM group (21.33 ± 8.64 pm) compared to BTF-OTM (46.16 ± 17.98); Dogs in group MTD-IM reached a higher sedation scores at each time point compared to MTD-OTM. The induction dose of propofol appears comparable among groups. Marked vasoconstriction was observed after OTM administration, as probably related to α2-agonists use. Emesis and sialorrhea occurred in two subjects of MTD-OTM group while only one dog presented sialorrhea in BTF-OTM group. In conclusion, OTM administration appears effective and easy to perform; it takes a longer time to achieve a good sedation score, probably related to a gradual absorption of drugs that also leads to a more gradual hemodynamic effects., International Journal of Health, Animal Science and Food Safety, V. 4, N. 1s (2017)

Oral-transmucosal (OTM) drug delivery refers to noninvasive and painless administration of medical preparations through any oral cavity membrane to achieve systemic effects (Sattar et al., 2014). Regarding sedative drugs, OTM administration is very attractive in veterinary medicine, especially for patients difficult to inject and restrain (Messenger et al., 2016). This study aims to compare the pharmacokinetics of dexmedetomidine after OTM and intramuscular (IM) administration combined with methadone. After obtaining Ethical Committee approval and owner’s written consent, eight dogs, were administered with dexmedetomidine (10 mg/kg) and methadone (0.4 mg/kg) by OTM and other 4 dogs by IM route. Blood samples were collected at prefixed times up to four hours. Dexmedetomidine was quantified by a validated HPLC-MS method. On dexmedetomidine concentrations, a pharmacokinetic analysis was carried out with a noncompartmental approach (Phoenix WinNonlin® 7.0, Pharsight, Cary, NC). Mean ± SD terminal half-lives of dexmedetomidine were 187.42 ± 109.66 and 94.78 ± 34.08 min after OTM and IM administration, respectively. Maximum serum (Cmax) concentrations were 0.83 ± 0.32 and 9.09 ± 2.46 ng/mL for OTM and IM administration, respectively. Time to maximum concentration (Tmax) were 44.38 ± 32.16 and 21.25±11.39 min by OTM and IM administration, respectively. Area under the curve from 0 to the last measured concentration (AUClast) were 103.75 ± 30.23 and 614.87 ± 77.15 min*ng/mL for OTM and IM administration, respectively. Cmax, Tmax and AUClast values by OTM route demonstrate a lower and delayed absorption of the drug compared to IM. To complete the study, the pharmacokinetic analysis of methadone is foreseen, so as a clinical trial to compare the clinical effects of the combination of dexmedetomidine and methadone by OTM and IM administration and to establish an effective dosage of oral-transumucosal route in dogs for this association., International Journal of Health, Animal Science and Food Safety, V. 4, N. 1s (2017)