Adverse effects of dopamine potentiation by long-term treatment with selegiline.

A patient with triosephosphate isomerase (TPI) deficiency exhibited worsening of abnormal involuntary movements of the dystonic type and developed psychiatric symptoms while on selegiline. When selegiline was stopped after 9 years of treatment, abnormal involuntary movements improved to pretreatment level and psychiatric behaviour returned to normal. Monoamine oxidase-B platelet activity was low in this patient.     

Failure to improve cigarette smoking abstinence with transdermal selegiline + cognitive behavior therapy

Aims To examine the effectiveness of transdermal selegiline for producing cigarette smoking abstinence. Design Adult smokers were randomly assigned to receive selegiline transdermal system (STS) or placebo given for 8 weeks. All participants received cognitive behavior therapy (CBT). Follow‐ups were conducted at 25 and 52 weeks. Setting Community smoking cessation clinic. Participants 243 adult smokers (≥18 years of age; ≥10 cigarettes/day). Measures Expired‐air carbon monoxide confirmed 7‐day point prevalence abstinence. Findings STS was not superior to placebo. More women than men were abstinent at 52 week follow‐up (28% vs 16%, P < 0.05). Behavioral activation (BAS) moderated treatment response (P = 0.01). The survival rate through week 52 for those with high ‘drive’ scores on the BAS was 47% if assigned to selegiline and 34% if assigned to placebo. The survival rate for those with low ‘drive scores’ on the BAS was 35% if assigned to selegiline compared to 53% if assigned to placebo. Conclusion Transdermal selegiline does not appear generally effective in aiding smoking cessation though there may be a selective effect in those smokers with low ‘behavioral activation’.     

Deprenyl (selegiline) in the treatment of Parkinson''s disease

ABSTRACT — The effects of deprenyl were investigated in 45 parkinsonian patients suffering from fluctuations in disability under long-term levodopa treatment. During a 1 to 3 month period of treatment, 5–10 mg of deprenyl caused a significant reduction in response fluctuations in 26 out of 45 patients (58 %). This improvement was only moderate (58 %) or minimal (42 %). Of 11 parkinsonian patients taking deprenyl with levodopa and benserazide for up to 4 years, 6 patients (55 %) showed moderate and 5 patients (45 %) minimal improvement initially. The improvement in response fluctuations was maintained during the follow-up period, although there was a clear decline in the degree of improvement. The addition of deprenyl to levodopa treatment also caused a further improvement in parkinsonian disability, which, however, decreased during the treatment period. Deprenyl appears to be a useful adjuvant to levodopa in patients with daily fluctuations in disability.     

Dose linearity study of selegiline pharmacokinetics after oral administration: evidence for strong drug interaction with female sex steroids

AIMS: The purpose of this study was to characterize the dose relationship of selegline and desmethylselegiline pharmacokinetics within the selegiline dose range from 5 to 40 mg. METHODS: Eight female subjects, of whom four were using oral contraceptives, ingested a single dose of 5 mg, 10 mg, 20 mg or 40 mg of selegiline HCl in an open four-period randomized study. Concentrations of selegiline and desmethlylselegiline in serum were measured by gas chromatography for 5 h. As it became evident that the use of oral steroids had a drastic effect on selegiline concentrations, the pharmacokinetic analyses were performed separately for oral contraceptive users and those not receiving any concomitant medication. RESULTS: The total AUC and Cmax of selegiline were 10-to 20-fold higher in those subjects taking oral steroids compared with subjects with no concomitant medication; this finding was consistent and statistically significant at all the four dose levels. The dose linearity of selegiline pharmacokinetics failed to be demonstrated in both groups. The AUC and Cmax of desmethylselegiline were only moderately higher (about 1.5-fold; P=NS at each dose level) in the subjects taking oral steroids than in those not receiving concomitant medication. The AUC values of desmethylselegiline increased in a dose linear manner in subjects with no concomitant medication, but not in the oral steroid group. The metabolic ratio (AUC(desmethylselegiline)/AUC(selegiline)) was several-fold lower in the group receiving oral steroids compared with the no-concomitant-medication group (P<0.005 at all the four dose levels). CONCLUSIONS: Concomitant use of oral contraceptives caused a drastic (20-fold) increase in the oral bioavailability of selegiline. The highly significant difference in the metabolic ratio between the groups provides evidence that the mechanism of the interaction between selegiline and female sex steroids involves reduced T-demethylation of selegiline. The present results suggest that concomitant use of selegiline with exogenous female sex steroids should be avoided or the dosage of selegiline should be reduced in order to minimize the risks of selegiline related adverse drug reactions.     

Region-specific alterations in the concentrations of catecholamines and indoleamines in the brains of young and old F344 rats after L-deprenyl treatment

The effects of L-deprenyl, a monoamine oxidase-B (MAO-B) inhibitor, on the concentrations of norepinephrine (NE), dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), serotonin (5-hydroxytryptamine), and 5-hydroxyindoleacetic acid (5-HIAA) in medial basal hypothalamus (MBH), substantia nigra (SN), striatum (Str), and nucleus accumbens (NAc) of young (3 month) and old (21 month) male F344 rats were examined after a 7-day wash-out period following 1, 15, or 30 days of deprenyl treatment in young rats and a 9-day wash-out period after a 10-week deprenyl treatment in old rats. The brain areas were microdissected and the concentrations of neurotransmitters were measured by High Performance liquid chromatography with electrochemical detection (HPLC-EC). Deprenyl administration following the drug wash-out period increased the concentrations of DOPAC in the SN, Str, and in the NAc of young rats but it was decreased in the NAc of old rats. The concentration of HVA was lower in the Str of young deprenyl-treated rats, and in the Str and NAc of old deprenyl-treated rats, but it was higher in the SN of young deprenyl-treated rats. The concentration of 5-HIAA was increased in the MBH, SN, and in the NAc of young deprenyl-treated rats, but it was decreased in the Str and NAc of old deprenyl-treated rats. The concentration of NE was increased in the MBH, SN, Str, and in the NAc of young rats treated with deprenyl and in the MBH of old deprenyl-treated rats. The concentration of 5-HT was increased in the SN of young deprenyl-treated rats. The concentration of DA increased in the Str of both young and old deprenyl-treated rats. We concluded that a drug wash-out period after deprenyl treatment differentially affects the metabolism of catecholamines and indoleamine depending on the region of the brain and that this effect may be due to variation in the kinetics of MAO inhibition.     

The effects of acute loading with levodopa and levodopa with selegiline on blood pressure and plasma norepinephrine levels in chronic Parkinson's disease patients

OBJECTIVES: Contradictory possible cardiovascular side effects of selegiline have been reported. Therefore, we studied the effect of acute administration of selegiline with levodopa (LD) compared with LD alone, on blood pressure, pulse and norepinephrine (NE) plasma levels, during an orthostatic test on chronically treated Parkinson's disease patients (PDpts) and controls. MATERIALS AND METHODS: Twelve PDpts treated with LD (group D), 12 PDpts treated with selegiline and LD (group S) and eight volunteers (CTRL) underwent the orthostatic test. Patients repeated the test twice, before and after acute loading with 125 mg LD (group D) and 125 mg LD +5 mg selegiline (group S). RESULTS: Group S showed more episodes of postural hypotension (n = 10; two symptomatic) than group D (n = 4) and CTRL (n = 2), however not statistically significant. Plasma NE also rose significantly higher (P < 0.001) in group S. CONCLUSION: PD patients treated with selegiline showed more orthostatism and higher plasma NE after submission to the orthostatic test. These findings may be relevant to explain its deleterious effect.     

Selegiline as a primary treatment of Parkinson's disease

In order to investigate the efficacy of selegiline as a primary treatment in Parkinson's disease (PD), we carried out a placebo controlled, double-blind prospective trial. Fifty-four de novo patients with PD were randomized to receive either selegiline (10 mg/day) or matching placebo. We continued the monotherapy until the initiation of levodopa therapy became necessary. The disability of the patients was evaluated with three different rating scales at baseline, after 3 weeks, 2, 4, 8, and 12 months, and every 4 months thereafter. Fifty-two patients were eligible for the final analysis: 27 in the selegiline group and 25 in the placebo group. The median duration of time without levodopa was 545 ± 90 days in the selegiline treated patients and 372 ± 28 days in the placebo treated ones (p = 0.03). The disability of the patients was significantly milder in the selegiline than in the placebo group up to 12 months. More patients showed symptomatic improvement in the selegiline than in the placebo group. However, the symptomatic effect alone did not explain the prolongation of the time without levodopa in the selegiline treated patients. Selegiline was well tolerated and no severe side effects were encountered.     

Selegiline Percutaneous Absorption in Various Species and Metabolism by Human Skin

Purpose. A Selegiline Transdermal System (STS) is under development for indications which may not be optimally or safely treated with oral selegiline. Studies were conducted to evaluate the in vitro penetration and skin metabolism of selegiline in order to better understand the toxicological findings and the observed plasma levels of selegiline and its metabolites in animals and man. Methods. In vitro penetration studies were conducted in four different species (male hairless mice, male and female rats, female dog and male Micropig^® and compared to human skin. In another study, viable human skin was used to estimate the extent of metabolism of selegiline by human skin using Franz diffusion cells. Results. Results indicated that female dog and male Micropig^® skin were reasonable animal models for 24 hour in vitro selegiline penetration through human skin. Penetration of selegiline through rat skin and hairless mouse skin was 2-fold and 3-fold higher than through human skin, respectively. Metabolism was negligible in human skin. Selegiline metabolites (L-methamphetamine and N-desmethylselegiline but not L-amphetamine) were detected at all time points but the extent of selegiline metabolism was negligible. The cumulative 24 hour in vitro selegiline permeation from a 1.83 mg/cm² STS through human skin was 5.0 mg. This was similar to the in vivo permeation in humans as assessed by residual patch analysis. Conclusions. The similarity of dog and human skin permeation results support the use of the dog as a species for evaluating the toxicology of transdermally-administered selegiline. Selegiline is not metabolized cutaneously and hence the metabolic profile following STS administration is likely due to hepatic metabolism only.     

Deprenyl (selegiline) combined with levodopa and a decarboxylase inhibitor in the treatment of Parkinson's disease

ABSTRACT — The purpose of this double-blind placebo controlled study was to estimate how much the levodopa dosage can be reduced, when deprenyl is used, without worsening the disease and to see whether deprenyl can reduce the "off-periods". The trial included 40 patients of both sexes with at least 3 years history of Parkinson's disease who were undergoing stabilized levodopa therapy. The deprenyl dosage was 5 mg daily in the first 4 weeks. The levodopa dosage was reduced until there was demonstrable impairment.
The trial demonstrates that with deprenyl the levodopa dosage can be reduced considerably without prejudicing the therapeutic outcome. Some patients showed improvement, and the "off-periods" were reduced in many cases.