First Case of Medically Assisted Suicide in Italy Set New Legal Perspectives.

Abstract: The first act of assisted suicide in Italy was recently carried out. This event is an absolute novelty for the country, affected by recent legislative changes aimed only at introducing the right to interrupt health treatments and, therefore, carry out exclusively omissive end-of-life acts. These normative provisions lay their foundations in a cultural context centered on the protection of the right to life and health; however, the cases that have occurred over time, including the famous story of DJ Fabo, have led the Constitutional Court to re-evaluate these dictates, introducing in 2019 the right to resort to assisted suicide procedures within well-defined areas, including incurability of the condition, the serious suffering of the individual and the retained ability to stand trial. The case addressed concerns a quadriplegic subject who was the victim of a road accident. Following consultation with a specialized institution, the subject made the decision to undergo an assisted sui-cide procedure in Italy. Having obtained the authorization from the competent authorities, he started a fundraiser to finance the devices and drugs required and, finally, he died. The opening by Italy towards the assisted suicide procedure represents a great step towards a broad context, as well as a decisive act for the purpose of protecting the right to self-determination of the individual. However, the current legislative framework presents significant criticalities and shortcomings. In first place, the dissonance between the laws in force and the judicial sentences is likely to generate problems of uneven application of the rules in a country dominated by the principle of Civil Law. Furthermore, the need for the applicant to fully self-finance the procedure clearly clashes with the constitutional principle of free access to care. Then emerges the need for a guideline document regarding the completion of the procedure itself, the times, methods and drugs implied, in order to significantly reduce the decision-making process by the ethics committees that still weighs on each individual case. Finally, conside-ring what has been observed on the subject of voluntary termination of pregnancy, it is necessary to ask what will be the general orientation of the doctors called to perform the act and whether they will be given the opportunity to express their refusal. The case analyzed could represent the beginning of a new era for Italian culture, but the large-scale application of assisted suicide procedures requires the introduction of legislative provisions that definitively eliminate the critical issues that have emerged so far.

High serum resistin in chronic viral hepatitis is not a marker of metabolic disorder.

BACKGROUND/AIMS: The role of resistin, an adipocyte-secreted hormone, in insulin resistance and in inflammation is controversial. In chronic hepatitis C, insulin resistance, type 2 diabetes and liver steatosis are frequent and inconsistently correlated to circulating resistin levels. In this study we assessed if viral aetiology and host metabolic parameters influence serum resistin in patients with HCV- and HBV- related chronic hepatitis. METHODOLOGY: Serum resistin was measured by ELISA and correlated to viral aetiology, age, gender, BMI, HOMA-IR, liver steatosis, hepatitis staging and grading, blood glucose, triglycerides and cholesterol in 43 patients with chronic hepatitis C, in 16 with chronic hepatitis B and in 29 healthy controls. RESULTS: In both groups of patients resistin was significantly higher than in controls, with higher values in HBV- than in HCV-patients (p = 0.0007). Resistin levels were correlated to aetiology and, inversely, to age (p = 0.026), diabetes (p = 0.036) and steatosis (p = 0.029). Multiple regression analysis showed that resistin concentration was dependent only on the aetiology of liver disease (p = 0.001). CONCLUSIONS: In chronic viral hepatitis serum resistin levels are high and not associated with altered metabolic parameters or with the histological activity of the disease. The meaning of higher resistin in HBV- than in HCV- chronic hepatitis is unclear.

Prognostic factors of survival in complicated viral and alcoholic cirrhosis without hepatocellular carcinoma. A retrospective study.

AIM: In several studies, attention is needed to one specific complication, in particularly to hepatocellular carcinoma, which modifies the natural history of liver cirrhosis. Thus, we performed a retrospective cohort analysis to clarify which complications, alone or in combination, are predictive factors of mortality in patients with viral or alcoholic cirrhosis without hepatocellular carcinoma. METHODS: Case records of 255 patients with decompensated viral or alcoholic cirrhosis between January 1990 and December 2000 were retrospectively analyzed. Relevant clinical and laboratory parameters, and their relationship to mortality, were studied. RESULTS: The mean duration of follow-up period was 29 months in which 178 patients (69.8%) died and 77 (31.8%) survived. None of the patients underwent liver transplantation. The cumulative mortality rate of patients with complicated cirrhosis was 38.8% after 1 year, 51.7% after 2 years, 61.1% after 3 years and 65.1% after 8 years. A multivariate Cox's model identified the following variables as significant: age (P=0.001), gastrointestinal bleeding (GB)-ascites combination (P=0.000), encephalopathy-GB-ascites (P=0.028), hepatorenal syndrome (HRS) (P=0.000), GB-spontaneous bacterial peritonitis (SBP) (P=0.001), alkaline phosphatase (ALP) (P=0.004) and the Child-Pugh score (P=0.000). CONCLUSION: The mortality in a group of patients with alcoholic cirrhosis is longer than in those with viral cirrhosis . Moreover, ascites in combination with other complications, HRS and hemorrage-SBP association are independent predictors of mortality in patients with complicated liver cirrhosis.

A new benzoxazine compound blocks KATP channels in pancreatic beta cells: molecular basis for tissue selectivity in vitro and hypoglycaemic action in vivo.

BACKGROUND AND PURPOSE: The 2-propyl-1,4 benzoxazine (AM10) shows a peculiar behaviour in skeletal muscle, inhibiting or opening the ATP-sensitive K(+) (KATP) channel in the absence and presence of ATP, respectively. We focused on tissue selectivity and mechanism of action of AM10 by testing its effects on pancreatic KATP channels by means of both in vitro and in vivo investigations. EXPERIMENTAL APPROACH: In vitro, patch-clamp recordings were performed in native pancreatic beta cells and in tsA201 cells expressing the Kir6.2 Delta C36 channel. In vivo, an intraperitoneal glucose tolerance test was performed in normal mice. KEY RESULTS: In contrast with what observed in the skeletal muscle, AM10, in whole cell perforated mode, did not augment KATP current (I(KATP)) of native beta cells but it inhibited it in a concentration-dependent manner (IC(50): 11.5 nM; maximal block: 60%). Accordingly, in current clamp recordings, a concentration-dependent membrane depolarization was observed. On excised patches, AM10 reduced the open-time probability of KATP channels without altering their single channel conductance; the same effect was observed in the presence of trypsin in the bath solution. Moreover, AM10 inhibited, in an ATP-independent manner, the K(+) current resulting from expressed Kir6.2 Delta C36 (maximal block: 60% at 100 microM; IC(50): 12.7 nM) corroborating an interaction with Kir. In vivo, AM10 attenuated the glycemia increase following a glucose bolus in a dose-dependent manner, without, at the dose tested, inducing fasting hypoglycaemia. CONCLUSION AND IMPLICATIONS: Altogether, these results help to gain insight into a new class of tissue specific KATP channel modulators.

Evaluation of the pharmacological activity of the major mexiletine metabolites on skeletal muscle sodium currents.

BACKGROUND AND PURPOSE: Mexiletine (Mex), an orally effective antiarrhythmic agent used to treat ventricular arrhythmias, has also been found to be effective for myotonia and neuropathic pain. It is extensively metabolized in humans but little information exists about the pharmacodynamic properties of its metabolites. EXPERIMENTAL APPROACH: To determine their contribution to the clinical activity of Mex, p-hydroxy-mexiletine (PHM), hydroxy-methyl-mexiletine (HMM), N-hydroxy-mexiletine (NHM) (phase I reaction products) and N-carbonyloxy beta-D-glucuronide (NMG) (phase II reaction product) were tested on sodium currents (I(Na)) of frog skeletal muscle fibres. Sodium currents were elicited with depolarizing pulses from different holding potentials (HP=-140, -100, -70 mV) and stimulation frequencies (0.25, 0.5, 1, 2, 5, 10 Hz) using the vaseline-gap voltage-clamp method. KEY RESULTS: All the hydroxylated derivatives blocked the sodium channel in a voltage- and use-dependent manner. The PHM, HMM and NHM metabolites were up to 10-fold less effective than the parent compound. However, HMM showed a greater use-dependent behaviour (10 Hz), compared to Mex and the other metabolites. Similar to Mex, these products behaved as inactivating channel blockers. Conjugation with glucuronic acid (NMG) resulted in almost complete abolition of the pharmacological activity of the parent compound. CONCLUSIONS AND IMPLICATIONS: Thus, although less potent, the phase I metabolites tested demonstrated similar pharmacological behaviour to Mex and might contribute to its clinical profile.

Posterior Reversible Encephalopathy Syndrome in late postpartum eclampsia.

Posterior Reversible Encephalopathy Syndrome (PRES) is a neurological complication associated with several medical conditions and it has been described in clinical findings of seizures, headache, vomiting, altered mental status, and visual changes and focal neurologic deficit, in conjunction with radiological findings of primarily posterior cerebral white matter edema of both cerebral hemispheres. PRES can develop in a wide array situations including pregnancy and postpartum in patients with or without symptoms and signs of eclampsia. A prompt diagnosis of PRES by magnetic resonance imaging and an immediate antihypertensive and anticonvulsant therapy can help to prevent serious complications. The clinical case presented deals with a 35 year-old pregnant woman whose history of eclampsia was observed after a cesarean section.

Effect of mexiletine on sea anemone toxin-induced non-inactivating sodium channels of rat skeletal muscle: a model of sodium channel myotonia.

The sea anemone toxin ATX II impairs skeletal muscle sodium channel inactivation, mimicking the persistent inward current observed in patients suffering from sodium channel myotonia. Mexiletine has beneficial effects on myotonia. To verify the efficiency of the drug on persistent inward current, we investigated the effect of 50 microM R(-)-mexiletine on sodium channels in cell-attached patches of rat skeletal muscle fibres, in the absence or presence of 2 microM ATX II. With the toxin, a proportion of channels displayed remarkable abnormal activity lasting the entire depolarisation, which resulted in a persistent inward current that represented up to 2.0% of the peak current. Mexiletine reduced by 75% the peak current elicited by depolarisation from -100 to -20 mV. This was due to the reduction by 60% of the maximal available peak current Imax and to the negative shift by -7 mV of steady-state inactivation. Mexiletine also greatly decreased the late current, but the effect was limited to 60% of reduction, comparable to that on Imax. Therefore mexiletine was able to block the ATX II-modified sodium channels, inhibiting the myotonia-producing persistent inward current.

A structure-affinity relationship study on derivatives of N-[2-[4-(4-Chlorophenyl)piperazin-1-yl]ethyl]-3-methoxybenzamide, a high-affinity and selective D(4) receptor ligand.

N-[2-[4-(4-Chlorophenyl)piperazin-1-yl]ethyl]-3-methoxybenzamide (1), a high-affinity and selective dopamine D(4) receptor ligand, was chosen as a lead, and structural modifications were done on its amide bond and on its alkyl chain linking the benzamide moiety to the piperazine ring and by preparing some semirigid analogues. The binding profile at dopamine D(4) and dopamine D(2), serotonin 5-HT(1A), and adrenergic alpha(1) receptors of 16 new compounds was determined. From the results emerged that the modification of the amide bond and the elongation of the intermediate alkyl chain caused a decrease in dopamine D(4) receptor affinity. All prepared semirigid analogues displayed D(4) receptor affinity values in the same range of the opened counterparts.

N-[2-[4-(4-Chlorophenyl)piperazin-1-yl]ethyl]-3-methoxybenzamide: a potent and selective dopamine D4 ligand.

A series of new 1-aryl-4-alkylpiperazines containing a terminal benzamide fragment or a tetralin-1-yl nucleus on the alkyl chain were synthesized and tested for binding at cloned human dopamine D4 and D2 receptor subtypes. A SAFIR (structure-affinity relationship) study on this series is herein discussed. The most relevant D4 receptor affinities were displayed by N-[omega-[4-arylpiperazin-1-yl]alkyl]-methoxybenzamides (compounds 5, 16-20), their IC50 values ranging between 0.057 and 7.8 nM. Among these, N-[2-[4-(4-chlorophenyl)piperazin-1-yl]ethyl]-3-methoxybenzamide (17) emerged since it exhibited very high affinity for dopamine D4 receptor (IC50 = 0.057 nM) with selectivity of >10 000 for the D4 versus the D2 receptor; compound 17 was also selective versus serotonin 5-HT1A and adrenergic alpha1 receptors.

1-aryl-4-[(5-methoxy-1,2,3, 4-tetrahydronaphthalen-1-yl)alkyl]piperazines and their analogues: influence of the stereochemistry of the tetrahydronaphthalen-1-yl nucleus on 5-HT1A receptor affinity and selectivity versus alpha1 and D2 receptors. 5.

Some 1-aryl-4-[(5-methoxy-1,2,3, 4-tetrahydronaphthalen-1-yl)-n-propyl]piperazines and their alkylamino and alkylamido analogues, previously studied as 5-HT1A ligands, were prepared in enantiomerically pure form, and their absolute configuration was determined by chemical correlation or by chiroptical properties. They were evaluated for in vitro 5-HT1A, D2, and alpha1 receptor affinity by radioligand binding assays, to study the influence of the chiral carbon atom of the tetrahydronaphthalene nucleus on the 5-HT1A affinity and selectivity. Results indicated that, as regarding the 5-HT1A receptor affinity, there was no difference in affinity between (-)- and (+)-enantiomers as well as the racemate of each compound. The stereochemistry, instead, influenced the selectivity: all (-)-enantiomers displayed affinity values higher than those of (+)-isomers at D2 receptors, and conversely, all (+)-enantiomers displayed affinity values higher than those of (-)-isomers at alpha1 receptors. As a result of this trend, it is not possible to predict the isomer with a better selectivity profile. However, compounds (S)-(+)-2, (S)-(+)-4, and (R)-(+)-6 displayed high affinity for the 5-HT1A receptor (IC50 values ranging between 7.0 and 2.3 nM) and good selectivity (>/=250-fold) versus both D2 and alpha1 receptors. Furthermore, compounds (S)-(+)-4 and (R)-(-)-4 were submitted to the [35S]GTPgammaS binding assay for a preliminary evaluation of their intrinsic activity on the 5-HT1A receptor.

New sigma and 5-HT1A receptor ligands: omega-(tetralin-1-yl)-n-alkylamine derivatives.

Two series of compounds that are structurally related to benzomorphans, derived by structural modification of arylpiperazines with high 5-HT1A affinity and moderate sigma affinity, were prepared in order to increase sigma affinity and selectivity. All new compounds are N-substituted-omega-(1,2,3,4-tetrahydronaphthalen-1-yl)- or -omega-(1,2-dihydronaphthalen-4-yl)-n-alkylamines with, in some cases, a methoxy group on the tetralin moiety. They were tested in radioligand binding assays on sigma ([3H]DTG and [3H]-(+)-pentazocine), D-2 dopaminergic, 5-HT1A and 5-HT2 serotonergic, and PCP (phencyclidine) receptors. A first set of compounds bearing a 4-(1-substituted)piperazine moiety as terminal fragment on the alkyl chain showed moderate to high sigma affinity (Ki = 5.3-139 nM), the most active and selective being 1-cyclohexyl-4-[3-(5-methoxy-1,2,3,4-tetrahydronaphthalen-1-yl)-n- propyl ]piperazine (14), with probable pronounced sigma 2 affinity (Ki = 5.3 nM on [3H]DTG and Ki = 71 nM on [3H]-(+)-pentazocine). Moreover, compound 13, a 1-benzylpiperazine analogue of 14, preserved a dual high 5-HT1A and sigma affinity (Ki = 3.6 nM on [3H]-5-HT and Ki = 7.0 nM on [3H]DTG). The second set of compounds includes some N-phenylalkyl derivatives of 3-(5-methoxy-1,2,3,4-tetrahydronaphthalen-1-yl)- n-propylamine that can be considered to be open-chain derivatives of 4-substituted-1-arylpiperazines. Among these compounds that had a lower activity toward sigma binding sites, a high 5-HT1A affinity was found for the N-(3-phenylpropyl) derivative 21 (Ki = 4.4 nM) which demonstrated very good selectivity.

Oxygen isosteric derivatives of 3-(3-hydroxyphenyl)-N-n-propylpiperidine.

Some substituted 3-phenylmorpholines (10a-e,j,k) and 3-thienylmorpholines (10f,g), isosteres of 3-(3-hydroxy-phenyl)-N-n-propylpiperidine (3-PPP), were prepared and submitted to binding assays on D-2 dopaminergic and 5-HT1 and 5-HT2 serotonergic receptors, in comparison with 3-PPP and its analogue 3a,b. The results show the loss of D-2 affinity for all morpholines, while a certain activity was still observable for piperidine derivatives. Regarding the serotonergic affinity, only chloro and methoxy derivatives (10a-d) were moderately active on the 5-HT1A receptor, either when the substituent was in the C-2 or C-3 position, whereas no tested compounds showed affinity toward the 5-HT2 receptor.

Stereospecificity of the chloride ion channel: the action of chiral clofibric acid analogues.

2-(p-Chlorophenoxy)isobutyric acid (clofibric acid (1) or CPIB) is a drug known to block chloride membrane conductance (GCl) in rat striated muscle. In the present study chiral analogues of CPIB (2-(p-chlorophenoxy)propionic acid (2) and 2-(p-chlorophenoxy)butyric acid (3)) have been tested to evaluate the influence of chirality on Cl ion flux in the channel. The results showed that the chloride channel conductance strongly depends on the absolute configuration: in fact, the S-(-) isomers of the tested compounds strongly decreased the GCl of skeletal muscle membrane, whereas the R-(+) isomers were virtually ineffective. These data allow the hypothesis that, like other ion channels present in various biological systems, the chloride channel of skeletal muscle membrane could also have a stereospecific binding site (or receptor) regulating chloride ion flux.

Novel potent sigma 1 ligands: N-[omega-(tetralin-1-yl)alkyl]piperidine derivatives.

A series of substituted N-[(tetralin-1-yl)alkyl]piperidines and a number of related N-di-n-propyl-[(tetralin-1-yl)alkyl]amines were prepared. Structural modifications such as piperidine substitutions, intermediate chain lengthening, and the nature of the aromatic ring were explored in order to identify structural requirements for selective sigma 1 affinity. They were tested in radioligand binding assays on sigma 1, 5-HT1A and 5-HT2 serotonergic, PCP (phencyclidine), and D-2 dopaminergic receptors. Almost all the compounds reported here showed a high to superpotent sigma 1 affinity, and some compounds also demonstrated a widespread selectivity over the other receptors. In [3H]-(+)-pentazocine binding, 3,3-dimethyl-1-[3-(5-methoxy-1,2,3,4-tetrahydronaphthalen-1-yl)-n- propyl] piperidine (24) and 3,3-dimethyl-1-[4-(1,2,3,4-tetrahydronaphthalen-1-yl)-n- butyl]piperidine (26) reached the lowest Ki values (0.4 and 0.8 nM, respectively); compound 24 also demonstrated a considerable PCP affinity (Ki = 34.2 nM), whereas compound 26 was suitably selective. Furthermore the presence of a 4-benzyl substituent on the piperidine ring (compound 16, Ki = 3.9 nM on sigma 1 sites) caused an increase in 5-HT1A affinity (Ki < 0.14 nM).

1-aryl-4-[(1-tetralinyl)alkyl]piperazines: alkylamido and alkylamino derivatives. Synthesis, 5-HT1A receptor affinity, and selectivity. 3.

The synthesis and binding profile on 5-HT1A, 5-HT2, D-1, D-2, alpha 1, and alpha 2 receptors of the N-4 long-chain arylpiperazines 22-40 are reported, where an amino or amido function is inserted into the intermediate chain linked to the alpha position of the tetralin nucleus. Unlike the buspirone analogues, for the amido derivatives studied in this paper, the terminal amide function of long-chain piperazines is not important for 5-HT1A receptor affinity binding, and its removal yields high-affinity 5-HT1A receptor agents.

N-[omega-(Tetralin-1-yl)alkyl] derivatives of 3,3-dimethylpiperidine are highly potent and selective sigma1 or sigma2 ligands.

Several 3, 3-dimethyl-N-[omega-(tetrahydronaphthalen-1-yl)alkyl]piperidine derivatives and some related compounds were prepared. Their affinities and sigma-subtype selectivities were investigated by radioligand binding assays, labeling sigma1 receptors with [3H]-SKF 10047 and sigma2 receptors with [3H]-DTG. Many tested compounds bound sigma1 and/or sigma2 receptors with nanomolar or subnanomolar IC50 values. Compound (+)-22, (+)-3,3-dimethyl-1-[3-(5-methoxy-1,2,3, 4-tetrahydronaphthalen-1-yl)-n-propyl]piperidine, was the most potent (IC50 = 0.089 nM) and selective sigma1 ligand (1340-fold), showing a 10-fold enantioselectivity. Compounds 29 (3, 3-dimethyl-1-[4-(6-methoxy-1,2,3, 4-tetrahydronaphthalen-1-yl)-n-butyl]piperidine) and 31 (3, 3-dimethyl-1-[5-(1,2,3, 4-tetrahydronaphthalen-1-yl)-n-pentyl]piperidine) were highly potent (IC50 = 0.016 nM and IC50 = 0.008 nM, respectively) and highly selective sigma2 ligands (more than 100000-fold).

Synthesis of new 2,6-prolylxylidide analogues of tocainide as stereoselective blockers of voltage-gated Na(+) channels with increased potency and improved use-dependent activity.

A series of tocainide chiral analogues were designed, synthesized, and evaluated in vitro, in pure enantiomeric form, as use-dependent blockers of skeletal muscle sodium channels to better understand the structural requirements responsible for the antimyotonic activity. The voltage clamp recordings showed a remarkable increase of both potency and use-dependent behavior with the analogue N-(2, 6-dimethylphenyl)-2-pyrrolidinecarboxamide (1a). In fact (R)-1a was 5-fold more potent than (R)-tocainide in producing the tonic block, i.e., the reduction of peak sodium current in resting conditions after application of the compound, but it was 21-fold more potent in condition of high frequency of stimulation (phasic block). Furthermore, as opposite to tocainide, this compound was also stereoselective, (S)-1a being 2-3-fold less potent than (R)-1a. The introduction in 1a of a methyl group in place of the hydrogen bonded to either the aminic nitrogen atom [N-(2, 6-dimethylphenyl)-1-methyl-2-pyrrolidinecarboxamide (2a)] or the amidic nitrogen atom [N-(2, 6-dimethylphenyl)-N-methyl-2-pyrrolidinecarboxamide (3a)] led unexpectedly to an inversion of stereoselectivity, the (S)-enantiomers being 3-fold more potent than the (R)-ones. The comparison between eutomers showed that (S)-2a and (S)-3a are almost equieffective to (R)-1a in producing a tonic block, the half-maximal concentrations being about 100 microM; however, the use-dependent behavior was remarkably decreased by the presence of the methyl group: i.e., the gain of potency observed at high frequency of stimulation amounted to 3 and 1.6 times for 2a and 3a, respectively. The replacement of both hydrogens bonded to the aminic and amidic nitrogen atoms resulted in N-(2,6-dimethylphenyl)-N, 1-dimethyl-2-pyrrolidinecarboxamide (4a) in which the (S)-isomer was still twice as potent as the (R)-one, but the absolute potency and mostly the use-dependent behavior were strongly reduced, showing therefore no clear advantages with respect to tocainide. The use-dependent behavior, which plays a pivotal role for antimyotonic activity, is strongly reduced by the presence of methyl groups on the nitrogen atoms, likely for modification of pK(a) and/or for constraint of molecular conformation.

High affinity and selectivity on 5-HT1A receptor of 1-aryl-4-[1-tetralin)alkyl]piperazines. 2.

Several 4-alkyl-1-arylpiperazines that present a tetralin moiety on the terminal part of the side chain were synthesized in order to increase the selectivity on the 5-HT1A versus D-2, alpha 1, sigma, and other 5-HT receptors. Many changes have been effected on previous structures of type 3(1-aryl-4-[3-(1,2-dihydronaphthalen-4-yl)-n-propyl]piperazines). Several synthetic procedures were followed to obtain the final products, depending on the presence or absence of a double bond, as well as of a heteroatom on the side chain. In the first case versatile use of Grignard reaction was made, whereas in the second one usual synthetic ways were applied. Final compounds were evaluated for in vitro activity on dopamine D-1 and D-2, serotonin 5-HT1A, 5-HT1B, 5-HT1C, and 5-HT2, alpha 1 adrenergic, and sigma receptors by radioreceptor binding assay. For the 2-MeO-Ph, 2-pyridyl, and unsubstituted phenyl N-piperazine derivatives, low IC50 values (0.3 nM) on 5-HT1A receptors and high selectivity values were observed.

Structure-activity relationship studies on the 5-HT(1A) receptor affinity of 1-phenyl-4-[omega-(alpha- or beta-tetralinyl)alkyl]piperazines. 4.

The synthesis of 1-phenylpiperazines, linked in the alpha or beta position of the tetralin moiety on the terminal part of the N-4 alkyl chain, and their radioligand binding affinities for 5-HT(1A), 5-HT(2A), D-1, D-2, alpha1, and alpha2 receptors along with SAR studies on the 5-HT(1A) receptor are reported. Several changes have been carried out on previous structures of type 2, by inserting the alkyl chain with variable length in the alpha or beta position of the tetralin moiety and by changing the position of the methoxy group on the aromatic ring of the tetralin nucleus. The highest affinity (IC50 = 0.50 nM) and selectivity for the 5-HT(1A) receptor were showed by 1-phenylpiperazine 2a with a three-membered alkyl chain bearing a 5-methoxytetralin-1-yl ring in the omega position.

Mixed 5-HT1A/D-2 activity of a new model of arylpiperazines: 1-aryl-4-[3-(1,2-dihydronaphthalen-4-yl)-n-propyl]piperazines. 1. Synthesis and structure-activity relationships.

A new model of 4-alkyl-1-arylpiperazines containing a terminal dihydronaphthalene fragment on the alkyl chain was synthesized in order to have mixed serotonergic and dopaminergic activity and to pursue the recent alternative approaches to the discovery of novel antipsychotic and anxiolytic agents. Title compounds were evaluated for in vitro activity on dopamine D-2 and serotonin 5-HT1A and 5-HT2 receptors by radioreceptor binding assays. They show high nanomolar affinity for 5-HT1A, moderate affinity for D-2, and low affinity for 5-HT2 receptors, and in particular, two compounds, 4-[3-(1,2-dihydro-6-methoxynaphthalen-4-yl)-n-propyl]-1-(2- methoxyphenyl)piperazine (8) and 4-[3-(1,2-dihydro-8-methoxynaphthalen-4-yl)-n-propyl]-1-(2- pyridyl)piperazine (15), show values (nM) of IC50 = 2.0 and 1.4 for 5-HT1A and IC50 = 90.6 and 119.3 for D-2, respectively. Some in vivo behavioral studies show compound 8 to be an antagonist on 5-HT1A receptors. These first findings place the new arylpiperazines on the same level as that of the azaspirone class, e.g., 1-(2-methoxyphenyl)-4-[4-(2-phthalimido)-n-butyl]piperazine (NAN-190) and buspirone.