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.

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.

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.

Serotonin syndrome caused by olanzapine and clomipramine.

We describe a case of severe serotonin syndrome. The patient was simultaneously taking the atypical antidepressant olanzapine and a tricyclical antidepressant, clomipramine. Symptoms included altered mental state resulting in coma, myoclonus, hyperreflexia, diaphoresis, diarrhoea, disorientation and fever. After suspension of antidepressant drugs, intensive symptomatic treatment and administration of biperiden and cyproheptadine, the patient's condition improved.

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.

[Pharmacological sympathetic block in complex regional pain syndrome]. / Blocco farmacologico del simpatico nella Complex Regional Pain Syndrome.

PURPOSE: The Complex Regional Pain Syndrome (CRPS) is a chronic pain state provoked by lesions of the soft tissues or of the bony tissues (type CRPS-I or reflex sympathetic dystrophy-RSD) or by lesions of the nerves (type CRPS-II or causalgia) with vegetative alterations (perspiration, vasomotory alterations) and trophic alterations (bony cutaneous atrophy, alopecia, articular contractures). The pharmacological block of the sympathetic nerves through a peripheral vein is inserted in the multidisciplinary approach that characterizes the therapy of this syndrome. MATERIALS AND METHODS: A retrospective survey was carried out on a group of 185 patients affected by RDS/CRPS with block of the sympathetic nerves through a peripheral vein with guanethidine. Superior limb: Inflation of the tourniquet till disappearance of the radial wrist. Cannulation of a peripheral vein with Butterfly needle n. 23. Guanethidine 10 mg, lidocaine 20 mg, sodic heparin 500 u.i, NaCl 0.9% 20 ml. Injection in 5 minutes. Permanence of the pneumatic tourniquet inflated above systolic blood pressure for 15 minutes. Deflation slowly. Inferior limb: Inflation of the tourniquet till disappearance of the pedidium wrist. Cannulation of a peripheral vein with Butterfly needle n. 23. Guanethidine 20 mg, lidocaine 40 mg, sodic heparin 1000 u.i, NaCl 0.9% 40 ml. Injection in 5 minutes. Permanence of the pneumatic tourniquet inflated above systolic blood pressure for 15 minutes. Deflation slowly. RESULTS: The first stage (hyperemic) showed the highest incidence of remissions: (83, 33%). Even in the second stage (dystrophic) the answer to the therapy has been fundamentally positive: (53, 68%). In the third stage (atrophic) the results have been more modest: (8, 33%). CONCLUSIONS: The block of sympathetic system with guanethidine is still an important method in the therapy of the CRPS; in fact it is surely less invading than the blocks of the stellate ganglion or of the lumbar sympathetic.

trans-4-[4-(Methoxyphenyl)cyclohexyl]-1-arylpiperazines: a new class of potent and selective 5-HT(1A) receptor ligands as conformationally constrained analogues of 4-[3-(5-methoxy-1,2,3,4-tetrahydronaphthalen-1-yl)propyl]-1-arylpiperazines.

The present paper concerns the influence of conformational parameters on the recognition by rat 5-HT1A receptors of derivatives 4-[3-(5-methoxy-1,2,3,4-tetrahydronaphthalen-1-yl)propyl]-1-(2-pyridinyl)piperazine (1a) and 3-(5-methoxy-1,2,3,4-tetrahydronaphthalen-1-yl)-N-[2-(2-pyridyloxy)ethyl]propanamine (3b), two highly potent and selective 5-HT1A receptor ligands. Fifteen corresponding flexible and rigid analogues were prepared following several synthetic routes and were tested in binding assays with radioligands at 5-HT1A, D2, and alpha1 receptors from rat brain membranes. Among the new derivatives emerged trans-4-[4-(3-methoxyphenyl)cyclohexyl]-1-(2-pyridinyl)piperazine (trans-8a) and trans-N-[4-(3-methoxyphenyl)cyclohexyl]-2-(2-pyridyloxy)ethylamine (trans-8b). These compounds can be considered as conformationally constrained analogues of compounds 1a and 3a, respectively. In fact, compounds trans-8a and trans-8b showed a marked enhancement in 5-HT1A receptor affinity when compared to the corresponding cis isomers. Because compound trans-8a was a potent and selective 5-HT1A ligand (K(i), nM: 5-HT1A = 0.028, D2 = 2194, alpha1 = 767), it was chosen as a lead to prepare other analogues that were tested at 5-HT1A, D2, and alpha1 receptors from rat brain membranes, showing high affinity at the 5-HT1A and selectivity vs D2 and alpha1 receptors. Selected compounds were tested for their affinity at the human cloned 5-HT1A, alpha1a, alpha1b, alpha1d receptor subtypes. They were also submitted to the [35S]GTPgammaS binding assay stimulating the 5-HT1A receptor-mediated G-protein activation, therefore behaving as full or as partial agonists. Finally, the ability of iv administration of trans-8a to induce fore-paw treading in rats was evaluated in comparison with 8-OH-DPAT. Although the affinity (K(i)) and in vitro activity (pD'2) of trans-8a at the 5-HT1A receptor were higher than those of 8-OH-DPAT, the compound was less potent than the reference standard in inducing the symptom.

Determination of dopamine D(4) receptor density in rat striatum using PB12 as a probe.

N-[2-[4-(4-Chlorophenyl)piperazin-1-yl]ethyl]-3-methoxybenzamide (PB12), a potent and selective dopamine D(4) receptor ligand, was used as a probe for the direct determination of the dopamine D(4) receptor density in rat striatum as an alternative to the subtraction method. The experiment was performed using [(3)H]spiroperidol to label D(2), D(3) and D(4) receptors and PB12 to determine directly dopamine D(4) receptor specific binding. The determined B(max) value was 82 fmol/mg protein. The contribution of the dopamine D(4) receptor to the overall population of D(2)-like receptors was 63%; however, this value cannot be considered reliable because of the observed difference in the kinetic profiles of D(2), D(3) and D(4) receptors.

Carboxylic acids and skeletal muscle chloride channel conductance: effects on the biological activity induced by the introduction of methyl groups on the aromatic ring of chiral alpha-(4-chloro-phenoxy)alkanoic acids.

One or two methyl groups have been introduced on the aromatic ring of two chiral clofibric acid analogs, 2-(4-chloro-phenoxy)propanoic and 2-(4-chloro-phenoxy)butanoic acids. The biological activity of the derivatives obtained (3-6) has been evaluated on the skeletal muscle chloride conductance (gCl). The results confirm the hypothesis of two different sites modulating chloride channel function, an excitatory site that increases channel activity and an inhibitory site that produces a channel block. In fact, this chemical modification strongly reduces the blocking activity of the (R)- and (S)-enantiomers in comparison with the parent compounds, but does not markedly affect the ability of the (R)-enantiomers to increase chloride channel conductance.

A multireceptorial binding reinvestigation on an extended class of sigma ligands: N-[omega-(indan-1-yl and tetralin-1-yl)alkyl] derivatives of 3,3-dimethylpiperidine reveal high affinities towards sigma1 and EBP sites.

New 1-[omega-(2,3-dihydro-1H-inden-1-yl)- and (2,3-dihydro-5-methoxy-1H-inden-1-yl)alkyl]- and 1-[omega-(1,2,3,4-tetrahydronaphthalen-1-yl)- and (6-methoxy- or 6-fluoro-1,2,3,4-tetrahydronaphthalen-1-yl)alkyl] derivatives of 3,3-dimethylpiperidine were synthesized, as homologous compounds of an existing series of sigma ligands, in order to carry out sigma receptor subtypes structure-affinity relationships. The new compounds and some of their related analogues, already reported, were tested in new multireceptorial radioligand binding assays. As reference compounds, the known sigma(1) ligands SA 4503, BD 1008 and NE 100 were also prepared and tested. All reported compounds showed high sigma(1) affinity assayed by (+)-[(3)H]-pentazocine on guinea-pig brain (apparent K(i)=1.75-72.2 nM) and moderate or low sigma(2) affinity by [(3)H]-DTG on rat liver, in contrast with previous results. One tertiary amine function spaced by a five-membered chain from a phenyl group is the structural feature shared by the most active compounds 26 and 43 and some reference sigma(1) ligands. The reported sigma(1) ligands, including reference compounds, also demonstrated a high affinity towards EBP (Delta(8)-Delta(7) sterol isomerase) site (apparent K(i)=0.48-14.8 nM) and some of them (37 and 44) were good ligands at L-type Ca(++) channel. 1-[4-(2,3-Dihydro-1H-inden-1-yl)butyl]-3,3-dimethylpiperidine (26) was the best mixed sigma(1) and EBP ligand (apparent K(i)=1.75 and 1.54 nM, respectively) with a good selectivity versus sigma(2) receptor (138- and 157-fold, respectively).

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.

Different behavior toward racemization in basic media from chiral analogs of clofibric acid, the active metabolite of the antilipidemic drug clofibrate.

Some chiral analogs of clofibric acid, the active metabolite of the antilipidemic drug clofibrate, show different configurational stability in basic conditions. Also, extensive racemization occurs when the corresponding optically active acid chlorides are treated with 3 alpha-tropanol, whereas no racemization takes place with 3 alpha-tropanol as hydrochloride salt and with 3 beta-tropanol and 1-methyl-4-hydroxy-piperidine as either the free base or hydrochloride salt. For these aminoalcohols, experimental evidence supports the hypothesis that a ketene intermediate is involved in the racemization process. Formation of intramolecular hydrogen bond is evoked to explain the different ability of aminoalcohols to induce ketene formation and consequent racemization.

Pharmacological characterization of chloride channels belonging to the ClC family by the use of chiral clofibric acid derivatives.

The enantiomers of 2-(p-chlorophenoxy)propionic acid (CPP) and of its analogs with substitutions on the asymmetric carbon atom were tested on human ClC-1 channel, the skeletal muscle chloride channel, after heterologous expression in Xenopus laevis oocytes, to gain insight in the mechanism of action of these stereoselective modulators of macroscopic chloride conductance (gCl) of rat striated fibers. By means of two microelectrode voltage clamp recordings, we found that S(-)-CPP shifted the activation curve of the ClC-1 currents toward more positive potentials and decreased the residual conductance at negative membrane potential; both effects probably account for the decrease of gCl at resting potential of native muscle fibers. Experiments on expressed Torpedo marmorata ClC-0 channels and a mutant lacking the slow gate suggest that S(-)-CPP could act on the fast gate of the single protochannels constituting the double-barreled structure of ClC-0 and ClC-1. The effect of S(-)-CPP on ClC-1 was markedly increased at low external pH (pH = 6), possibly for enhanced diffusion through the membrane (i.e., because the compound was effective only when applied to the cytoplasmic side during patch clamp recordings). The R(+)-isomer had little effect at concentrations as high as 1 mM. The CPP analogs with an ethyl, a phenyl, or an n-propyl group in place of the methyl group on the asymmetric center showed a scale of potency and a stereoselective behavior on ClC-1 similar to that observed for blocking gCl in native muscle fibers. The tested compounds were selective toward the ClC-1 channel. In fact, they were almost ineffective on an N-terminal deletion mutant of ClC-2 that is volume- and pH-independent while they blocked wild-type ClC-2 currents only at high concentrations and independently of pH and drug configuration, suggesting a different mechanism of action compared with ClC-1. No effects were observed on ClC-5 that shows less than 30% homology with ClC-1. Thus, CPP-like compounds may be useful both to gain insight into biophysical properties of ClC-1 and for searching tissue-specific therapeutic agents.

1-Substituted-4-[3-(1,2,3,4-tetrahydro-5- or 7-methoxynaphthalen-1-yl)propyl]piperazines: influence of the N-1 piperazine substituent on 5-HT1A receptor affinity and selectivity versus D2 and alpha1 receptors. Part 6.

In the present paper, we report the synthesis and the binding profiles on 5-HT1A, D2, and alpha1 receptors of 1-substituted-4-[3-(5- or 7-methoxy-1,2,3,4-tetrahydronaphthalen-1-yl)propyl]piperazine derivatives 19-32 and some related heteroalkyl derivatives 33-35. The results obtained are compared to those previously reported for the 1-phenyl, 1-(2-methoxyphenyl), 1-(2-pyridyl) analogues 2-9. The results pointed out the critical role of the group linked in the N-1 position of the piperazine in terms of 5-HT1A binding affinity. In fact, 1-cyclohexyl, 1-(3-benzisoxazolyl), 1-(benzothiazole-2-carbonyl), 1-(2-benzothiazolyl), 1-(2-quinolyl) substituted piperazines 21-30 displayed moderate or low 5-HT1A receptor affinity; on the contrary, 1-(3-benzisothiazolyl) and 1-(1-naphthalenyl) substituted piperazines 19, 20 and 32 displayed high 5-HT1A receptor affinity, the Ki values being in the subnanomolar range. Furthermore, compounds 19, 20 and 32 demonstrated better selectivity over alpha1 receptors than the reference compounds 2-9.

Homologation of mexiletine alkyl chain and stereoselective blockade of skeletal muscle sodium channels.

The optical isomers (-)-(S)- and (+)-(R)-3-(2, 6-dimethylphenoxy)-2-methyl-1-propanamine (Me2), homologues of the antiarrhythmic and antimyotonic drug mexiletine (Mex), were synthesized and assayed as new potential antimyotonic agents. As observed with Mex, Me2 exhibits an enantioselective behaviour. Tests carried out on sodium currents of single muscle fibres of Rana esculenta demonstrated that (-)-(S)- and (+)-(R)-Me2 were less potent than Mex in producing tonic block, but showed a higher use-dependent block. (-)-(S)-Me2 and (-)-(R)-Mex were also used to study the excitability of muscle fibres of myotonic ADR mice, a phenotype of a recessive form of low G(Cl) myotonia. (-)-(S)-Me2 reduced spontaneous discharges and after discharges better than (-)-(R)-Mex in agreement with the use-dependent block of sodium currents.

Facile entry to (-)-(R)- and (+)-(S)-mexiletine.

The title compounds, 1a and 1b, have been synthesized in a three-step sequence starting from (-)-(S) and (+)-(R)-propylene oxide, respectively, in acceptable overall yields. The enantiomeric excess values for 1a and 1b were 96% and 93% respectively, as assessed by HPLC analysis on a chiral stationary phase of the corresponding N-acetyl derivatives. The synthetic route herein presented may represent a facile entry to highly enriched mexiletine enantiomers, alternative to those previously reported in the literature.

Molecular determinants of mexiletine structure for potent and use-dependent block of skeletal muscle sodium channels.

On the basis of the information about drug receptor on voltage-gated sodium channels, mexiletine (Mex) analogs with substitutions at either the asymmetric carbon atom or the aromatic ring were synthesized as pure enantiomers. The compounds were tested in vitro for their ability to produce voltage- and use-dependent block of sodium currents (I(Na)) of frog muscle fibers by the vaseline-gap voltage-clamp method. In all experimental conditions, the drug potency was highly correlated with the lipophilicity of the group on the asymmetric center, the derivative with a benzyl moiety (Me6) having IC(50) values more than 10 times lower than those of Mex, followed by the phenyl (Me4) and the isopropyl (Me5) derivative. All of the compounds showed a further reduction of IC(50) values at depolarized membrane potentials and at high frequency of stimulation (10 Hz). Mex and Me5, but not Me4, produced a stereoselective tonic block of I(Na), the R-(-) isomers being 2-fold more potent than the S-(+) ones. The removal of both methyl groups from the aromatic ring of Mex (Me3) caused a 7-fold reduction of the potency, whereas similar substitutions on the phenyl derivative Me4 (Me7 and Me8) produced opposite effects. In fact, the IC(50) of R-(-) Me7 for use-dependent block of I(Na) was 30 times lower than that of R-(-) Mex. Me8 and Me7 were stereoselective during both tonic and use-dependent blockade. All of the compounds left-shifted the steady-state inactivation curves in relation to their potency and to the duration of the inactivating prepulse. Finally, the presence of apolar groups on the asymmetric center of mexiletine is pivotal to reinforce hydrophobic interactions with the proposed aromatic residues at the receptor, and lead to potent and therapeutically interesting inactivated channel blockers.

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.