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Biomedical subjects

P R Sundaresan

Publications and source records attributed to P R Sundaresan.

17 recordsLinked to original sources
PubMed1992

Long-term weight control study. I (weeks 0 to 34). The enhancement of behavior modification, caloric restriction, and exercise by fenfluramine plus phentermine versus placebo.

To investigate the value of anorexiant medications as an adjunct to other forms of weight control therapy, we studied 121 people in a 34-week, double-blind clinical trial of 60 mg extended-release fenfluramine plus 15 mg phentermine resin versus placebo added to behavior modification, caloric restriction, and exercise. Participants weighed 130% to 180% (154% +/- 1.2%, mean +/- SEM) of ideal body weight (1983 Metropolitan Life tables) and were in good health. By week 34, participants receiving active medication lost an average of 14.2 +/- 0.9 kg, or 15.9% +/- 0.9% of initial weight (n = 58), versus a loss of 4.6 +/- 0.8 kg or 4.9% +/- 0.9% of initial weight by subjects taking placebo (n = 54; p less than 0.001). On visual analog scales, participants rated fenfluramine plus phentermine as more helpful than placebo (50.3 +/- 0.5 versus 20.3 +/- 0.3) and not bothersome (fenfluramine plus phentermine, 17.4 +/- 0.3 versus 13.5 +/- 0.2). Blood pressure decreased and pulse remained unchanged in both groups. Dry mouth was the most common adverse effect in subjects receiving fenfluramine plus phentermine; all adverse effects decreased after 4 weeks. Only nine participants left the study in the first 34 weeks. Two subjects from each group left the study as a result of adverse effects. Overall, fenfluramine plus phentermine used in conjunction with behavior modification, caloric restriction, and exercise aided weight loss and continued to be efficacious for 34 weeks.

Adult↗
PubMed1992

Long-term weight control study. II (weeks 34 to 104). An open-label study of continuous fenfluramine plus phentermine versus targeted intermittent medication as adjuncts to behavior modification, caloric restriction, and exercise.

Between weeks 34 and 104, we explored different schema for administering fenfluramine plus phentermine in open-label fashion. At week 34, the original placebo group participants began taking fenfluramine plus phentermine (placebo-to-active group). Those receiving fenfluramine plus phentermine between weeks 6 and 34 either continued to receive medication or began targeted intermittent therapy. Participants who did not lose 10% of initial weight received an augmented dose (60 mg fenfluramine plus 30 mg phentermine. The placebo-to-active group lost an additional 9.1 +/- 0.8 kg (mean +/- SEM) in the period from week 34 to week 60. At week 60, they were assigned to either continue medication, intermittent therapy, or augmented therapy. More than 68% (83) of the original participants completed up to study week 104. At that point, overall weight loss was 10.8 +/- 0.7 kg (11.6 +/- 0.8% of initial weight); participants who continued to receive fenfluramine plus phentermine lost 11.6 +/- 0.8 kg, participants receiving intermittent therapy lost 11.6 +/- 1.3 kg, and participants receiving augmented therapy lost 6.5 +/- 1.5 kg. Although 41% of the participants complained of dry mouth, neither serious adverse effects nor evidence of medication abuse appeared. There were 29 dropouts in the period from weeks 34 to 104. Sixteen of those were related to medication (adverse effects, lack of efficacy, and fear of medication). Overall, fenfluramine plus phentermine used in conjunction with behavior modification, caloric restriction, and exercise continued to be efficacious for up to 2 years.

Adult↗
PubMed1992

Long-term weight control study. III (weeks 104 to 156). An open-label study of dose adjustment of fenfluramine and phentermine.

Between weeks 104 and 156 we attempted to optimize response by adjusting the doses of fenfluramine and phentermine. Dosing changes were based on an algorithm that aimed to achieve 120% of ideal body weight (IBW) while minimizing adverse effects. The dose groups were as follows: stage I, 30 mg fenfluramine plus 15 mg phentermine in the morning; stage II--continuous or targeted intermittent, 60 mg fenfluramine plus 15 mg phentermine in the morning; stage III, 60 mg fenfluramine plus 30 mg phentermine in the morning; stage IV, 60 mg fenfluramine plus 30 mg phentermine in the morning and 30 mg fenfluramine in the evening; and stage V, 60 mg fenfluramine plus 30 mg phentermine in the morning and 60 mg fenfluramine in the evening. Seventy-seven participants began this segment of the study and 59 completed to week 156. Completers of this segment of the study gained an average of 2.7 +/- 0.5 kg between weeks 104 and 156 but remained 9.4 +/- 0.8 kg (10.5%) below baseline. On average, weight loss from baseline by group was as follows: for stage I (n = 2), 14.1 +/- 6.8 kg; for stage II continuous (n = 14), 10.9 +/- 0.7 kg; for stage II targeted intermittent (n = 7), 8.8 +/- 2.4 kg; for stage III (n = 9), 7.7 +/- 2.6 kg; for stage IV (n = 8), 10.5 +/- 2.6 kg; and for stage V (n = 19), 8.4 +/- 2.4 kg. Upward dose adjustment (n = 36) resulted in further weight loss in 11 and no gain in six participants.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Long-term weight control study. IV (weeks 156 to 190). The second double-blind phase.

To assess continued efficacy of anorexiants after 3 years of use, 52 participants (43% of those starting) entered a second double-blind trial to compare 60 mg sustained-release fenfluramine plus 15 mg phentermine resin versus placebo added to behavior modification, caloric restriction, and exercise. Although participants in both the active medication and placebo groups gained weight, participants receiving fenfluramine plus phentermine (n = 27) gained significantly (p less than 0.01) less (4.4 +/- 0.5 kg or 5.3% +/- 0.5% of initial weight) than participants receiving placebo (n = 24) (6.9 +/- 0.8 kg or 8.5% +/- 1.1% of initial weight). At week 190, both groups were still below their initial weight (fenfluramine plus phentermine group, 5.0 +/- 1.4 kg; placebo group, 2.1 +/- 1.2 kg; p less than 0.01). Overall, 12 participants (23.5% of those still in the study) were greater than or equal to 10% below initial weight. One participant dropped out during this phase because of personal reasons and loss of medication efficacy. During the 30 weeks, participants receiving fenfluramine plus phentermine had 26 moderate or severe complaints versus eight participants receiving placebo. Fenfluramine plus phentermine provided better appetite control and only slightly more bother. Analysis of participant response in this phase by treatment assignment in the first double-blind phase (weeks 6 to 34) indicated that initial receipt of medication did not have negative learning effects. Eleven participants receiving active medication between weeks 6 and 34 and receiving placebo between weeks 160 to 190 gained 5.1 +/- 1.0 kg. In contrast, 13 participants originally taking placebo gained 8.3 +/- 9 kg in this second double-blind phase.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Long-term weight control study. V (weeks 190 to 210). Follow-up of participants after cessation of medication.

Participants who completed up to week 190 in the long-term weight control study were monitored after cessation of medication between weeks 190 and 210. Caloric restriction, behavior modification sessions, exercise reinforcement, and physician visits continued. We assessed whether or not participants had reset their weight control mechanisms and compared the effect of stopping medication under open-label conditions (weeks 190 to 210) with the results of stopping anorexiants under double-blind conditions (weeks 160 to 190). At week 210, participants were, on average, 1.4 +/- 1.0 kg (mean +/- SEM, 1.5% +/- 1.1%) below their weights at baseline (week 0). Of the 48 participants who remained in the study, 13 were still 5% or more and seven were 10% or more below their initial weights. On average, participants gained 2.7 +/- 0.5 kg (3.2%) in the period from weeks 190 to 210. Those who had been taking medication in the period from weeks 160 to 190 gained weight at a somewhat faster rate than those who had been taking placebo. However, participants who had transferred from fenfluramine plus phentermine to no medication in this phase gained at a slower rate than participants who had changed from fenfluramine plus phentermine to placebo under double-blind conditions at week 160 (0.195 kg per week versus 0.277 kg per week). The findings indicate that participants had difficulty maintaining weight loss without anorexiant medications. Despite long periods of time at weights much lower than baseline, permanent resetting of weight control mechanisms could not be shown for most participants.

Adult↗
PubMed1992

Long-term weight control study. VI. Individual participant response patterns.

We analyzed the individual response patterns of all 121 participants who entered the study. Fifty-one participants completed up to week 190. In 26 completers, the response pattern consisted of an initial beneficial effect (greater than or equal to 6 months of weight loss greater than or equal to 10% from baseline) and later success (weight loss of greater than or equal to 10% from baseline at week 160). These successful participants had lost 14.1 +/- 1.0 kg (mean +/- SEM); 15.9% +/- 0.9% of initial weight) at week 160 and 8.1 +/- 1.2 kg (9.1% +/- 1.3% of initial weight) at week 190. A second pattern observed in 16 completers consisted of initial benefit and later partial success (loss of 0.1% to 9.9% at week 160). Other response patterns observed in completers included showing initial benefit only (n = 3) and no success (n = 6). Seventy of the 121 participants left the study before week 190. There were 22 "dropout successes" who had consistent weight loss for 1 year or more and were greater than or equal to 10% below their initial weights at time of dropout. Fifteen "dropouts with initial benefit" stayed in the study for greater than or equal to 1 year with initial benefit (weight loss greater than or equal to 10% from baseline maintained for greater than or equal to 6 months). Medication-related reasons accounted for only 10 of the 37 dropouts in the group with initial or later benefit. Minimal benefit was seen in 17 dropouts. Another 16 were in the study less than 1 year. Analysis of individual participant responses made some other generalizations possible. Participants receiving continuous medication lost more weight and had fewer adverse effects than those receiving targeted intermittent medication. Upward dose adjustment appeared to help 24 participants achieve the criteria for late or partial success. Analyses of individual participant responses can suggest ways to optimize anorectic medication use for individual patients.

Adult↗
PubMed1992

Long-term weight control study. VII (weeks 0 to 210). Serum lipid changes.

We analyzed serum total cholesterol, triglycerides, and lipoprotein profile changes occurring in the participants (N = 121) through 210 weeks of the study. On average, baseline lipid levels were within normal limits. The most consistent changes occurred in the high-density lipoprotein cholesterol (HDL-C), serum total cholesterol/HDL-C ratios, and triglyceride levels. HDL-C increased significantly (p less than 0.01), compared with baseline, by 10% at week 34, 15% at week 54, 19% at week 104, and 27% at week 139. At week 210, 20 weeks after treatment had ended, HDL-C was 15% higher than baseline. At weeks 34, 54, 104, and 139, the serum total cholesterol/HDL-C ratio was significantly decreased, compared with baseline, by 9%, 19%, 17%, and 25%, respectively. At week 210, serum total cholesterol/HDL-C ratio was 8% less than week 0. Compared with baseline, triglyceride levels decreased significantly by 21%, 31%, 29%, and 29% at weeks 34, 54, 104, and 139, respectively. At week 210, triglyceride levels were 16% below baseline. Total cholesterol levels and low-density lipoprotein cholesterol (LDL-C) showed less dramatic changes. Patterns of lipid and lipoprotein changes were qualitatively similar between men and women. However, greater decreases in serum total cholesterol, LDL-C, and triglyceride levels were observed in participants with high (n = 10) compared with low (n = 10) baseline lipid levels. Cholesterol changes were not affected by anorexiant medications. However, triglyceride levels at week 34 were significantly (p less than 0.025) less in the participants treated with anorexiants.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1979

Methodology for demonstrating sustained efficacy of hypnotics: a comparative study of triazolam and flurazepam.

To test for sustained hypnotic efficacy, triazolam (0.6 mg) or flurazepam (30 mg) was given to chronic insomniac patients for 7 consecutive nights in parallel, double-blind design. Triazolam at this dose was an effective hypnotic by all usual subjective measures and did not produce appreciable hangover. Flurazepam performed similarly. For either drug, comparison of the mean scores for the first 2 nights with that for the last 2 nights for any of the parameters did not reveal any significant difference. Thus, both triazolam and flurazepam showed sustained efficacy for 1 week at these doses. Some interesting theoretical and practical questions about the measurement of sustained efficacy of hypnotics in situations of repetitive dosing were addressed by the study. While a placebo control is desirable, the results obtained may be uninterpretable. An acute-care hospital setting may not be the ideal setting for doing such studies. There were indications from the study that the first-night results in a hypnotic clinical trial may be atypical.

Adult↗
PubMed1977

Rate of metabolism of retinol and retinoic acid-maintained rats after a single dose of radioactive retinol.

The half-life and metabolism of vitamin A were determined in a group of vitamin A-deficient retinoic acid supplemented rats after a single dose of 340 mug of [6,7-14C2] retinol. The total daily urinary radioactivity, plotted semilogarithmically as a function of days after injection, revealed three pools for retinol and/or metabolites in the rat: (1) a rapidly declining pool with half-life of 0.75 day; (2) a slowly declining pool with a constant rate of decrease and (3) a pool with a half-life of 13 days which begins at approximately 6 weeks after dose. The total daily fecal radioactivity also indicated three pools with half-lives of 2,28.5 and 11.5 days. The effect of retinoic acid feeding was observed on the fifth day after supplementation, as indicated by a decrease in the total daily urinary radioactivity. Thus, retinoic acid is probably in the metabolic pathway of retinol. The half-life and metabolism time of liver vitamin A in these rats were determined as 7 and 10 days, respectively. The specific activities of liver retinyl esters and retinol determined at different intervals after dose indicated continuous mixing of radioactive retinol with a pool of endogenous retinol. Blood retinol levels indicated normal values at 1 week after dose. However, they decreased at 2 weeks after dose and remained constant until the sixth week. The specific activity of blood retinol did not change indicating rapid equilibration after initial mixing and no further dilution from endogenous source.

Animals↗
PubMed1977

Influence of zinc deficiency on retinal reductase and oxidase activities in rat liver and testes.

The influence of zinc deficiency on vitamin A metabolism in rats was investigated by assessing two specific enzymes involved in its metabolism viz retinal reductase and retinal oxidase in the liver as well as in the testes. The activity of retinal reductase in the liver was not altered in zinc deficiency. Retinal oxidase activity on the other hand, was increased approximately 1.5 fold over the pair-fed controls. In contrast, both retinal reductase and oxidase in the testes were decreased during zinc deficiency. The effects of zinic deficiency on vitamin A metabolism in the liver could be partly attributed to the secondary effect of reduced food intake and growth. However, the effects seen in the testes on the metabolic enzymes of vitamin A appear to be due to zinc deficiency per se. The liver concentration of vitamin A (microgram/g) as well as total vitamin A (microgram/liver) were higher in the zinc-deficient rats when compared to the zinc-sufficient rats although not significantly different from the pair-fed controls. In aggreement with previous reports, the plasma vitamin A in zinc-deficient rats were found to be markedly lowered compared to zinc sufficient ad libitum controls.

Alcohol Oxidoreductases↗
PubMed1977

Vitamin A contents of rat intestinal epithelium and jejunal mucinous adenocarcinoma.

Concentrations of retinol and tetinyl esters were assayed in rat intestinal mucosa and in chemically induced transplanted mucinous adenocarcinoma of the jejunum. Lipid extract from the tissues was chromatographed on deactivated alumina to isolate retinol and retinyl esters, which were determined by specific spectrofluorometry. Normal intestinal mucosa tissue contains 556 ng of retinol equivalents as retinyl esters and 303 ng of free retinol/g of wet tissue. The concentration of retinyl esters in the intestinal mucosa from rats carrying the transplanted tumor was 341 ng/g wet tissue; no free retinol was detected in the small intestinal epithelium of these rats. Liver tissue from the tumor-bearing rats contained 157 microng of retinol equivalents as retinyl esters and 136 microng of free retinol/g of wet tissue. The concentration of vitamin A per cell in the adenocarcinoma tissue was about 20 times less than that in intestinal epithelium.

Adenocarcinoma, Mucinous↗
PubMed1975

Tissue distribution of retinol and its metabolites after administration of double-labelled retinol.

The tissue concentrations and distribution of radioactivity present in retinol and its metabolites were investigated in vitamin A-deficient rats 24h after injection of physiological doses (10mug) of [6, 7-14C2, 11,12-3H2] retinol. The highest concentration of radioactivity was observed in the adrenals, followed by kidney, spleen, liver, intestine and blood. The total radioactivity was greatest in urine, followed in descending order by liver, kidney, blood and intestine. The 14C/3H ratios of crude light-petroleum extracts in the liver, intestines, lungs, heart and faeces were similar to the ratio of the injected retinol dispersion. However, the 14C/3H ratios in the adrenals, kidney, spleen, blood, brain and urine were quite different from that of injected retinol. Alumina chromatography of the kidney and intestinal extracts demonstrated that retinol and retinyl palmitate are the principal forms of vitamin A present. However, alumina chromatography of the liver extract did not reveal the presence of retinol but yielded a major compound with a low 14C/3H ratio. That this compound was not retinol was shown by its inability to react with ethanolic HC1 to yield anhydroretinol. The distribution of radioactivity in ether-soluble, acidic and water-soluble fractions of urine indicated that most of the radioactivity was present in the acidic and water-soluble fractions. The 14C/3H ratios in ether-soluble and acidic fractions were higher than that of injected retinol, whereas in the water-soluble fraction the ratio was similar to the injected material.

Adrenal Glands↗
PubMed1975

Imipramine-mediated interference with levodopa absorption from the gastrointestinal tract in man.

The effect of imipramine on the absorption of a single dose of levodopa was studied in male volunteers. By delaying gastric emptying and retarding delivery to intestinal absorptive sites, imipramine interfered with the absorption of levodopa. This action caused by the anticholinergic effect of imipramine. The retardation of transit of levodopa also caused the elaboration of therapeutically inactive metabolites of levodopa in the gastrointestinal tract. Antidepressants and levodopa are often given together, and this combination may interfere with the absorption and efficacy of levodopa in the treatment of Parkinson's disease.

Adult↗
PubMed1975

Distribution of chlorpromazine in the gastrointestinal tract of the rat and its effect on absorptive function.

The distribution of [14C]chlorpromazine was studied in segments of the gastrointestinal tract of the rat after an oral dose of 20 mg/kg (1-2 muc). The total radioactivity in the gastrointestinal tract was, respectively, 43.2 +/- 3.6, 28.9 +/- 2.2 and 14.1 +/- 1.1 (mean +/- S.E. percent administered dose) at 2, 6 and 24 hours after dosing. The maximum observed total radioactivity in the different segments occurred at different times after dosing. The percentage of total radioactivity present in each tissue as unchanged [14C]chlorpromazine decreased with time in all the tissues. At all time points, this parameter also showed a consistent pattern: % stomach greater than % duodenum greater than % jejunum greater than % ileum. The effect of chronic administration of [14C]chlorpromazine on intestinal absorptive function was studied by the everted sac technique. Mucosal transport of L-[14C]methionine was significantly inhibited (24.4% of control), but no effect on transport of D-[14C]xylose was observed.

Animals↗