Cardiovascular effects of buccal exposure to dermal nicotine patches in the dog: a comparative evaluation.

OBJECTIVE: Safety concerns have been raised over the possible effects of inappropriate exposure to transdermal nicotine patches. This study was initiated to determine whether placement of these products into the mouth could affect cardiovascular function. METHODS: In a series of 10 anesthetized beagle dogs, Nicoderm, Habitrol, ProStep I (Intact), ProStep D (Damaged) transdermal nicotine products or the Skoal Bandit smokeless tobacco plug were placed in the buccal cavity for 5 minutes. Systemic arterial blood pressure and the electrocardiogram were monitored for up to 90 minutes after exposure with blood samples at intervals during the first 10 minutes for plasma nicotine concentration. RESULTS: The systolic and diastolic arterial blood pressures and heart rate increased within 2 minutes of buccal exposure to either the intact or the damaged ProStep nicotine product. Ventricular arrhythmias were observed in 6 of 10 dogs exposed to the intact patch and 7 of 10 dogs exposed to the damaged patch during the period of maximal cardiovascular response. Modest increases in systemic blood pressure and heart rate were seen with the Nicoderm and Habitrol products but not with the Skoal Bandit. The increases in systemic arterial pressure and heart rate occurring after exposure to ProStep were significantly more severe than those observed after Nicoderm and Habitrol. Mean peak nicotine levels of 9.8 microg/mL (ProStep 1), 5.4 microg/mL (ProStep D), 3.4 microg/mL (Habitrol), 2.5 microg/mL (Nicoderm), and 0.12 microg/mL (Skoal Bandit) were detected within 2 to 10 minutes after buccal placement of the product. CONCLUSIONS: Certain transdermal nicotine patches, when applied to a nondermal site such as the buccal cavity for a short period (5 minutes) can rapidly provoke significant cardiovascular alterations (hypertension, tachycardia, and ventricular arrhythmias). The magnitude of the cardiovascular responses occurring after buccal exposure to a product such as ProStep could pose a risk to susceptible individuals.

3-substituted-1,2-benzisoxazoles: novel antipsychotic agents.

A series of 3-substituted-6-fluoro-1,2-benzisoxazoles (II) was synthesized and evaluated for potential antipsychotic activity. Many of the compounds displayed potent antipsychotic-like activity in the apomorphine induced climbing in mice (CMA) or spiroperidol binding assays, and compound 42 (HRP 392, 1-[3-(6-fluoro-1,2-benzisoxazol-3-yl)propyl]-4-(2-methoxyphenyl) piperazine) was selected for more detailed antipsychotic evaluation in a battery of preclinical assays. The results of these studies suggests that 42 is a potential antipsychotic drug with less propensity for EPS than some standard neuroleptics in monkeys. The compound was advanced for toxicological evaluation.

Novel tetracyclic spiropiperidines. 4. Synthesis and pharmacological evaluation of spiro- and 6,7-dihydrospiro[benzo[b]pyrrolo[3,2,1-jk][1,4]benzodiazepine-2 (1H),4'-piperidine]s.

A previously described series of 1-arylspiro[indoline-3,4'-piperidine]s was reported by us to possess significant antidepressant properties. This biological activity was found to be at a maximum among those compounds bearing an ortho substituent (e.g., NH2 as in 1) in the pendant aryl ring. In order to explore further this "ortho effect", we synthesized cyclic analogues of type 3 and 4 in which the position of the o-NH2-substituted aryl group is conformationally restricted and defined. When tested for antidepressant activity by tetrabenazine ptosis prevention in mice, it was found that restriction of rotation of the pendant o-aminophenyl group in these rigid analogues resulted in a loss of antidepressant properties. However, analgesic activity was retained and even improved by this molecular constraint.

Novel tetracyclic spiropiperidines. 3. 1-arylspiro[indoline-3,4'-piperidine]s as potential antidepressants.

A series of 1-arylspiro[indoline-3,4'-piperidine]s was synthesized and evaluated for potential antidepressant activity by tetrabenazine (TBZ) ptosis prevention and potentiation of 5-hydroxytryptophan (5-HTP) induced head twitching in pargyline-pretreated rats. Marked TBZ activity was observed with analogues bearing an ortho substituent on the pendant aromatic ring, as exemplified by lead compound 25a, 1-(2-chlorophenyl)spiro[indoline-3,4'-piperidine], which was also very active in potentiating 5-HTP stereotypy and yohimbine toxicity, as well as in inhibiting the muricidal behavior in rats. The potent in vivo activity of 25a, coupled with weak to moderate in vitro activity with respect to the blockade of neuronal reuptake of biogenic amines, seems to suggest a profile atypical of tricyclic antidepressants.

Tricyclics with analgesic and antidepressant activity. 2. [[(Alkylamino)ethyl]thio]dibenzo[b,f]thiepins and 10,11-dihydro derivatives.

A series of [[(alkylamino)ethyl]thio]dibenz[b,f]thiepins (III) and their 10,11-dihydro derivatives (IV) was synthesized and subjected to broad analgesic/CNS screening. Preliminary results indicated a combination of analgesic/antidepressant profiles, similar to that observed for the [[(alkylamino)ethyl]thio]dibenz[b,f]oxepins (I) and their corresponding dihydro derivatives (II). The most active congener from the present series, 10b, shows an antinociceptive potency in the pentazocine range as assessed by phenyl-p-quinone-induced writhing (PQW) and tail flick in mice. It is also more than twice as active as imipramine in preventing tetrabenazine-induced ptosis (TBZ), a test widely recognized to be of predictive value for clinically efficacious antidepressants.

(+/-)-4-Aryl-4,5-dihydro-3H-1,3-benzodiazepines. 1. Synthesis and evaluation of (+/-)-4,5-dihydro-2,3-dimethyl-4-phenyl-3H-1,3-benzodiazepine and analogues as potential antidepressant agents.

A series of (+/-)-4,5-dihydro-4-phenyl-3H-1,3-benzodiazepines and (+/-)-4,5-dihydro-4-phenyl-1H-1,3-benzodiazepines was synthesized as part of a program to develop novel psychotropics. Of these compounds, (+/-)-4,5-dihydro-2,3-dimethyl-4-phenyl-3H-1,3-benzodiazepine (10a, HRP 543) emerged as a potential antidepressant. In in vivo mouse tests (inhibition of tetrabenazine-induced ptosis and potentiation of yohimbine toxicity) which are predictive of antidepressant-like activity, 10a is comparable to amitriptyline. The similarity is also maintained in vitro, as both 10a and amitriptyline inhibit norepinephrine and serotonin uptake into rat brain synaptosomes. No significant inhibition of rat brain monoamine oxidase A or B was found with 10a, nor did the compound potentiate tryptamine-induced seizures. On chronic administration, the number of cortical beta-adrenergic receptor sites was similarly reduced by 10a and desipramine. The anticholinergic activity of clinically useful antidepressants, such as amitriptyline, is a proposed cause of side effects which reduce patient compliance. In contrast to the tricyclics, 10a apparently lacks anticholinergic activity, as evidenced in vitro by negligible displacement of [3H]quinuclidinyl benzylate from rat brain muscarinic receptors and in vivo by insignificant antagonism of the cholinergic stimulation produced by physostigmine or oxotremorine. These data suggest that 10a may be clinically useful as a novel nontricyclic antidepressant which is devoid of anticholinergic side-effect liability. Further evaluation of 10a in nonrodent species is in progress.

(+/-)-4-Aryl-4,5-dihydro-3H-1,3-benzodiazepines. 2. Nuclear-substituted analogues of (+/-)-4,5-dihydro-2,3-dimethyl-4-phenyl-3H-1,3-benzodiazepine and (+/-)-4,5-dihydro-2-ethyl-3-methyl-4-phenyl-3H-1,3-benzodiazepine as potential antidepressant agents.

Antidepressant-like activity, as evidenced by marked inhibition of tetrabenazine-induced ptosis, was previously reported for (+/-)-4,5-dihydro-4-phenyl-3H-1,3-benzodiazepine derivatives. Since optimal antitetrabenazine activity was associated with (+/-)-4,5-dihydro-2,3-dimethyl-4-phenyl-3H-1,3-benzodiazepine (9k, HRP 543) and the 2-ethyl-3-methyl analogue (10k), the synthesis and evaluation of nuclear-substituted derivatives of these two compounds was also investigated. The initial synthesis involved Friedel-Crafts acylation of substituted benzenes with 2-nitrophenylacetyl chloride to afford 1-aryl-2-(2-nitrophenyl)ethanones 2, which were converted in five steps to (+/-)-alpha-aryl-N-methyl-2-nitrobenzeneethanamines 7. Greater flexibility with respect to the introduction of nuclear substituents was achieved by conversion of 2-nitrotoluene derivatives to 2 via acylation of intermediate beta-(dimethylamino)-2-nitrostyrenes with various aroyl chlorides and hydrolysis. Reductive amination of 2 with methylamine and sodium cyanoborohydride afforded 7 directly and significantly reduced the number of synthetic steps. Reduction of 7a-j to diamines 8a-j and cyclization with appropriate ortho esters gave nuclear-substituted analogues of 9k and 10k. Marked antitetrabenazine activity was associated with many of these compounds. Significant enhancement of activity with respect to the unsubstituted analogues 9k and 10k was not observed, with the exception of 9c which appeared to be slightly more potent than 9k.

Synthesis of spiro[isobenzofuran-1(3H),4'-piperidines] as potential central nervous system agents. 6. Synthesis, 13C NMR, and biological evaluation of cis- and trans-4-amino-3'-arylspiro[cyclohexane-1,1'(3'H)-isobenzofuran] derivatives.

4-(Dimethylamino)- and 4-(methylamino)-3'-arylspiro[cyclohexane-1,1'(3'H)-isobenzofuran] derivatives were prepared as analogues of previously reported 3-arylspiro[isobenzofuran-1(3H),4'-piperidines]. Metalation of benzanilide with n-butyllithium, addition of 4-(dimethylamino)cyclohexanone, and acidification afforded a mixture of cis- and trans-4-(dimethylamino)spiro[cyclohexane-1,1'(3'H)-isobenzofuran]-3'-ones (1a,b), which were separated by fractional crystallization. Addition of aryllithium or aryl Grignard reagents to 1a,b and formic acid reduction afforded cis- and trans-4-(dimethylamino)-3'-arylspiro[cyclohexane-1,1'(3'H)-isobenzofurans] 3a-f, which were converted to secondary amine analogues 5a-e. Tentative stereochemical assignments are based on chemical arguments and are supported by 13C NMR chemical shift data. Marked inhibition of tetrabenazine-induced ptosis is a property of most antidepressants, and significant antitetrabenazine activity is observed for several of these compounds. Optimal antitetrabenazine activity is associated with the cis-3'-phenyl series, and the cis secondary amine 5a is approximately twice as potent as the cis tertiary amine 3a. The various compounds are relatively weak with respect to potentiation of L-5-hydroxytryptophan-induced seizures.

Novel tetracyclic spiropiperidines. 1. 3-Aryl-1,3-dihydrospiro[benzo[c]thiophene-1,4'-piperidines] as potential antidepressants.

A series of 3-aryl-1,3-dihydrospiro[benzo[c]thiophene-1,4'-piperidine] derivatives was synthesized and evaluated pharmacologically for potential psychotropic activity. Potent antidepressant-like activity was noted throughout the series, as assessed by tetrabenazine (TBZ) ptosis prevention in mice and potentiation of 5-hydroxytryptophan (5-HTP) induced behavioral effects in rats. A possible therapeutic advantage of the title compounds appears to be the overall low anticholinergic potential in comparison with the classic tricyclic antidepressants. Several congeners with nuclear halogen substitution also exhibited CNS stimulant properties, as evidenced by their ability to induce a dopamine agonist-like stereotypy and to increase the spontaneous motor activity in mice.

7-(Aminoacyl) and 7-(aminoalkyl) derivatives of 1,2,6,7-tetrahydroindolo[1,7-ab][1,5]benzodiazepines as potential antidepressant agents.

The synthesis of 7-(aminoacyl) and 7-(aminoalkyl) derivatives of 1,2,6,7-tetrahydroindolo[1,7-ab][1,5]benzodiazepines is described. These compounds were evaluated for antidepressant activity by their ability to inhibit tetrabenazine-induced ptosis in mice. Many compounds were found to be active in this animal model, and structure-activity relationships are discussed. Two analogues in particular, one from the 7-(aminoacyl) series (13) and one from the 7-(aminoalkyl) series (26), were of comparable potency to the antidepressant drugs desipramine and amitriptyline.

Tricyclics with analgesic and antidepressant activity. 1. [[(Alkylamino)ethyl]thio]dibenz[b,f]oxepins and 10,11-dihydro derivatives.

A series of [[(alkylamino)ethyl]thio]dibenz[b,f]oxepins (I) and their 10,11-dihydro derivatives (II) was synthesized and subjected to broad analgesic/CNS screening. Several analogues of both types, carrying small N-substituents and frequently a nuclear fluorine function, have been found to possess potent analgesic activity in the phenylquinone writhing assay (PQW) and the tail-flick test in mice. Many of these compounds also exhibited significant activity in antagonizing tetrabenazine-induced ptosis, as exemplified by 10b, 16b, and 18b. Results from the mouse jumping test indicated low physical dependence potential for these compounds, and further evidence for a nonnarcotic profile was provided by the absence of significant naloxone interactions with the tail-flick response. Compound 10b did not produce tolerance in mice following chronic administration in the PQW screen.

Synthesis of spiro[isobenzofuran-1(3H),4'-piperidines] as potential central nervous system agents. 5. Conformationally mobile analogues derived by furan ring opening.

Synthesis and antitetrabenazine activity of 4-[2-(arylmethyl)phenyl]piperidines and 4-(benzyloxy)-4-phenylpiperidines, prepared as simplified and possibly more readily synthesized analogues of 3-phenylspiro[isobenzofuran-1 (3H),4'-piperidine], are reported. Several 4-[2-(arylmethyl)phenyl]piperidines display antitetrabenazine activity comparable to imipramine or amitriptyline but are two- to fourfold less active than analogous 3-arylspiro[isobenzofuran-1(3H),4'-piperidines]. Structure--activity relationships for 4-[2p(arylmethyl)phenyl]piperidines are generally similar to the profile established for 3-arylspiro[isobenzofuran-1(3H),4'-piperidines]. Significant antitetrabenazine activity is associated only with derivatives where the arylmethyl group is ortho to the piperidine ring. 4-(Benzyloxy)-4-phenylpiperidines and 4-[2-(arylmethyl)phenyl]-4-piperidinols and the corresponding methyl ethers and esters display weak to modest antitetrabenazine activity. 4-[2-(Arylmethyl)phenyl]-1,2,3,6-tetrahydropyridine derivatives, at best, exhibit modest antitetrabenazine activity, with the exception of 4-[2-(phenylmethyl)phenyl]-1,2,3,6-tetrahydropyridine which is approximately equipotent with amitriptyline. The results of these investigations allow certain speculations to be made with respect to the role of the furan ring in the 3-arylspiro[isobenzofuran-1(3H),4'-piperidines] and antitetrabenazine activity.

Synthesis of spiro[isobenzofuran-1(3H),4'-piperidines] as potential central nervous system agents. 4. Central nervous system depressants.

The synthesis of 1'-[3-(4-fluorobenzyoyl)propyl]-3-phenylspiro[isobenzofuran-1(3H),4'-piperidine] (2a) and eight halo and methoxy analogues is described. The compounds were generally more potent per os than chlorpromazine in the Sidman avoidance paradigm in rats and less potent than haloperido. 1'-[3-(4-Fluorobenzoyl)propyl]-3-(4-fluorophenyl)spiro[isobenzofuran-1(3H),4'-piperidine] (2e) approached the per os potency of haloperidol in this test and was shown to be active in inhibiting monkey avoidance also. Compound 2e was much less active than haloperidol in antagonizing apomorphine-induced emesis in dogs, apomorphine-induced stereotypy in rats, and amphetamine-induced circling in lesioned rats. This lack of nonselective, dopamine-receptor blocking effects makes 2e attrative as a potential neuroleptic.

Synthesis of spiro[isobenzofuran-1(3H),4'-piperidines] as potential central nervous system agents. 2. Compounds containing a heteroatom attached to nitrogen.

The synthesis and antitetrabenazine activity of a series of N-heteroatom derivatives of 3-phenylspiro[isobenzofuran-1,4'-piperidines] are reported. Optimal antitetrabenazine activity is associated with compounds containing a sterically unhindered, basic nitrogen. Hydroxylamines 6, 11, 12, and 13 possess the most significant activity with ED50's of 1.4, 3.5, 4.7, and 4.0, respectively.