An Ethical Argument for Ending Human Trials of Amyloid-Lowering Therapies in Alzheimer's Disease

Given the past two decades of over 40 failed trials of amyloid-lowering therapies in Alzheimer's Disease (AD), many of which succeeded in lowering amyloid as designed, we present an ethical argument for emptying the drug pipeline of tests of amyloid-lowering agents so as to end the historical dominance of the amyloid-reducing therapeutic approach in AD.

Alzheimer's Disease Puzzle: Delving into Pathogenesis Hypotheses

Alzheimer's disease (AD) is a prevalent neurodegenerative disease characterized by both amnestic and non-amnestic clinical manifestations. It accounts for approximately 60-70% of all dementia cases worldwide. With the increasing number of AD patients, elucidating underlying mechanisms and developing corresponding interventional strategies are necessary. Hypotheses about AD such as amyloid cascade, Tau hyper-phosphorylation, neuroinflammation, oxidative stress, mitochondrial dysfunction, cholinergic, and vascular hypotheses are not mutually exclusive, and all of them play a certain role in the development of AD. The amyloid cascade hypothesis is currently the most widely studied; however, other hypotheses are also gaining support. This article summarizes the recent evidence regarding major pathological hypotheses of AD and their potential interplay, as well as the strengths and weaknesses of each hypothesis and their implications for the development of effective treatments. This could stimulate further studies and promote the development of more effective therapeutic strategies for AD.

[Light chain amyloidosis]

Light chain amyloidosis (AL) is a rare protein deposition disease. It is caused by a clonal plasma cell or B‑cell disease in the bone marrow. With the exception of the central nervous system, all organs can be affected by amyloid deposits. Cardiac involvement is the most frequent organ manifestation that leads to significantly increased mortality when it is diagnosed at an advanced stage. The causal treatment of AL amyloidosis is reduction of amyloidogenic light chains by chemotherapy. Early diagnosis of the disease is essential to reduce early mortality, to effectively treat patients and to prevent further deterioration of organ function. New treatment approaches for AL amyloidosis are aimed at inhibiting amyloid formation or degradation of amyloid in organs.

RNA-targeting and gene editing therapies for transthyretin amyloidosis

Transthyretin (TTR) is a tetrameric protein synthesized mostly by the liver and secreted into the plasma. TTR molecules can misfold and form amyloid fibrils in the heart and peripheral nerves, either as a result of gene variants in TTR or as an ageing-related phenomenon, which can lead to amyloid TTR (ATTR) amyloidosis. Some of the proposed strategies to treat ATTR amyloidosis include blocking TTR synthesis in the liver, stabilizing TTR tetramers or disrupting TTR fibrils. Small interfering RNA (siRNA) or antisense oligonucleotide (ASO) technologies have been shown to be highly effective for the blockade of TTR expression in the liver in humans. The siRNA patisiran and the ASO inotersen have been approved for the treatment of patients with ATTR variant polyneuropathy, regardless of the presence and severity of ATTR cardiomyopathy. Preliminary data show that therapy with patisiran improves the cardiac phenotype rather than only inducing disease stabilization in patients with ATTR variant polyneuropathy and concomitant ATTR cardiomyopathy, and this drug is being evaluated in a phase III clinical trial in patients with ATTR cardiomyopathy. Furthermore, ongoing phase III clinical trials will evaluate another siRNA, vutrisiran, and a novel ASO formulation, eplontersen, in patients with ATTR variant polyneuropathy or ATTR cardiomyopathy. In this Review, we discuss these approaches for TTR silencing in the treatment of ATTR amyloidosis as well as the latest strategy of genome editing with CRISPR-Cas9 to reduce TTR gene expression.

Amyloid seeding as a disease mechanism and treatment target in transthyretin cardiac amyloidosis

Transthyretin (TTR) is a tetrameric transport protein mainly synthesized by the liver and choroid plexus. ATTR amyloidosis is characterized by the misfolding of TTR monomers and their accumulation within tissues as amyloid fibres. Current therapeutic options rely on the blockade of TTR production, TTR stabilization to maintain the native structure of TTR, amyloid degradation, or induction of amyloid removal from tissues. “Amyloid seeds” are defined as small fibril fragments that induce amyloid precursors to assume a structure rich in β-sheets, thus promoting fibrillogenesis. Amyloid seeds are important to promote the amplification and spread of amyloid deposits. Further studies are needed to better understand the molecular structure of ATTR seeds (i.e. the characteristics of the most amyloidogenic species), and the conditions that promote the formation and multiplication of seeds in vivo. The pathological cascade may begin months to years before symptom onset, suggesting that seeds in tissues might potentially be used as biomarkers for the early disease stages. Inhibition of amyloid aggregation by anti-seeding peptides may represent a disease mechanism and treatment target in ATTR amyloidosis, with an additional benefit over current therapies.

Update in the Pharmacologic Treatment of Diabetes Mellitus

There are now more than 20 million people in America with diabetes mellitus (DM), and the prevalence of this illness continues to increase especially in those with type 2 DM. Over the past decade, research in the area of DM treatment has focused on pharmacologic approaches to modifying glucose metabolism as well as on lifestyle interventions to prevent and manage DM. Pharmacologic research has been guided by an improved understanding of the human physiology of glucose metabolism, allowing for development of new hormonal drug therapies and improved insulin formulations. As a result, there are several new pharmacologic treatments now available or on the horizon for DM. In this article, the authors review the first of the new hormonal therapies for DM, with a focus on information that will be useful for diabetes educators including the medication actions, side effects, patient counseling points, monitoring, and place in therapy in comparison to existing DM treatments. This series on new therapies has been divided into 3 parts, with this first part devoted to an update on the new incretin mimetic and amylin analog agents recently approved for use in DM. Subsequent parts in this series will focus on the new insulin products and oral therapies available or soon to be available. Cases will be used to assist with understanding the type of patient who will benefit from each of these new therapies.

Amyloid fibrils activate B-1a lymphocytes to ameliorate inflammatory brain disease

Amyloid fibrils composed of peptides as short as six amino acids are therapeutic in experimental autoimmune encephalomyelitis (EAE), reducing paralysis and inflammation, while inducing several pathways of immune suppression. Intraperitoneal injection of fibrils selectively activates B-1a lymphocytes and two populations of resident macrophages (MΦs), increasing IL-10 production, and triggering their exodus from the peritoneum. The importance of IL-10-producing B-1a cells in this effective therapy was established in loss-of-function experiments where neither B-cell-deficient (μMT) nor IL10(-/-) mice with EAE responded to the fibrils. In gain-of-function experiments, B-1a cells, adoptively transferred to μMT mice with EAE, restored their therapeutic efficacy when Amylin 28-33 was administered. Stimulation of adoptively transferred bioluminescent MΦs and B-1a cells by amyloid fibrils resulted in rapid (within 60 min of injection) trafficking of both cell types to draining lymph nodes. Analysis of gene expression indicated that the fibrils activated the CD40/B-cell receptor pathway in B-1a cells and induced a set of immune-suppressive cell-surface proteins, including BTLA, IRF4, and Siglec G. Collectively, these data indicate that the fibrils activate B-1a cells and F4/80(+) MΦs, resulting in their migration to the lymph nodes, where IL-10 and cell-surface receptors associated with immune-suppression limit antigen presentation and T-cell activation. These mechanisms culminate in reduction of paralytic signs of EAE.

Effect of Pramlintide on Weight in Overweight and Obese Insulin-Treated Type 2 Diabetes Patients

OBJECTIVE

Several randomized, placebo-controlled, double-blind trials in insulin-treated patients with type 2 diabetes have shown that adjunctive therapy with pramlintide reduces hemoglobin (Hb)A1c with concomitant weight loss. This analysis further characterizes the weight-lowering effect of pramlintide in this patient population.

RESEARCH METHODS AND PROCEDURES

This pooled post hoc analysis of two long-term trials included all patients who were overweight/obese at baseline (BMI > 25 kg/m2), and who were treated with either 120 microg pramlintide BID (n = 254; HbA1c 9.2%; weight, 96.1 kg) or placebo (n = 244; HbA1c 9.4%; weight, 95.0 kg). Statistical endpoints included changes from baseline to week 26 in HbA1c, body weight, and insulin use.

RESULTS

Pramlintide treatment resulted in significant reductions from baseline to week 26, compared with placebo, in HbA1c and body weight (both, p < 0.0001), for placebo-corrected reductions of -0.41% and -1.8 kg, respectively. Approximately three times the number of patients using pramlintide experienced a > or = 5% reduction of body weight than with placebo (9% vs. 3%, p = 0.0005). Patients using pramlintide also experienced a proportionate decrease in total daily insulin use (r = 0.39, p < 0.0001). The greatest placebo-corrected reductions in weight at week 26 were observed in pramlintide-treated patients with a BMI >40 kg/m2 and in those concomitantly treated with metformin (both, p < 0.001), for placebo-corrected reductions of -3.2 kg and -2.5 kg, respectively.

DISCUSSION

These findings support further evaluation of the weight-lowering potential of pramlintide in obese patients with type 2 diabetes.

Adjunct therapy for type 1 diabetes mellitus

Insulin replacement therapy in type 1 diabetes mellitus (T1DM) is nonphysiologic. Hyperinsulinemia is generated in the periphery to achieve normal insulin concentrations in the liver. This mismatch results in increased hypoglycemia, increased food intake with weight gain, and insufficient regulation of postprandial glucose excursions. Islet amyloid polypeptide is a hormone synthesized in pancreatic beta cells and cosecreted with insulin. Circulating islet amyloid polypeptide binds to receptors located in the hindbrain and increases satiety, delays gastric emptying and suppresses glucagon secretion. Thus, islet amyloid polypeptide complements the effects of insulin. T1DM is a state of both islet amyloid polypeptide and insulin deficiency. Pramlintide, a synthetic analog of islet amyloid polypeptide, can replace this hormone in patients with T1DM. When administered as adjunctive therapy to such patients treated with insulin, pramlintide decreases food intake and causes weight loss. Pramlintide therapy is also associated with suppression of glucagon secretion and delayed gastric emptying, both of which decrease postprandial plasma glucose excursions. Pramlintide therapy improves glycemic control and lessens weight gain. Agents that decrease intestinal carbohydrate digestion (alpha-glucosidase inhibitors) or decrease insulin resistance (metformin) might be alternative adjunctive therapies in T1DM, though its benefits are marginally supported by clinical data.

Patient reported outcomes in adults with type 2 diabetes on basal insulin randomized to addition of mealtime pramlintide or rapid-acting insulin analogs

OBJECTIVE

To determine whether treatment satisfaction and quality of life were affected by adding mealtime pramlintide or rapid-acting insulin analogs (RAIAs) to basal insulin therapy for patients with inadequately controlled type 2 diabetes.

RESEARCH DESIGN AND METHODS

In this 24-week open-label, multicenter study of adults with type 2 diabetes, mealtime pramlintide (PRAM) (120 microg fixed dose; n = 56) or titrated RAIAs (n = 56) was added to basal insulin therapy with or without oral antidiabetic medications.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.Gov NCT00467649.

MAIN OUTCOME MEASURES

Quality of life (Diabetes Distress Scale - DDS, and Pittsburgh Sleep Quality Index - PSQI), and treatment satisfaction (Diabetes Treatment Satisfaction Questionnaire - DTSQ, and Pramlintide Treatment Satisfaction Questionnaire - PRAM-TSQ) were assessed at baseline and week 24. Mixed-effect models estimated mean group changes from baseline to week 24 (adjusted for baseline scores) in patient reported outcomes.

RESULTS

PRAM patients experienced significant improvement in total diabetes distress, while RAIA patients did not; both groups experienced significant improvement in regimen-related distress and physician-related distress. Between-group differences in DDS measures were not significant. PRAM patients experienced significant improvement in sleep latency and daytime dysfunction, while RAIA patients did not; the difference between groups was significant for daytime dysfunction. Both treatment groups experienced significant improvement in most individual DTSQ items and total diabetes treatment satisfaction, while only PRAM patients experienced significant improvement in perceived hypoglycemia. Between-group differences in DTSQ measures were not significant. Both treatment groups experienced significant improvement in most individual PRAM-TSQ items and total treatment satisfaction; RAIA patients experienced increased eating flexibility and reduced perceived weight control. PRAM patients experienced significantly better perceived weight and appetite control than RAIA patients.

LIMITATIONS

The sample size was relatively small and there were few non-white subjects. The schedule for implementation of change in therapy may have affected study outcomes.

CONCLUSIONS

Adding pramlintide on a background of basal insulin improved some aspects of treatment satisfaction and quality of life relative to adding rapid-acting insulin analogs.

Amylin(1-8) is devoid of anabolic activity in bone

Amylin(1-8), a cyclic peptide consisting of the eight N-terminal amino acids of the 37-amino acid peptide amylin, has been shown to induce proliferation of primary osteoblasts and to induce bone formation in healthy male mice, whereas no data on efficacy in bone disease-related models have been reported. Therefore, we evaluated any effects of amylin(1-8) in ovariectomized rats with established osteopenia, a model for postmenopausal osteoporosis. At doses up to 100 nmol/kg/day, a dose highly effective in healthy mice, amylin(1-8) was unable to increase bone mineral density in ovariectomized rats during an 8-week treatment period. Histomorphometric analysis of the tibia indicated that amylin(1-8) did not change bone histomorphometric parameters. In an attempt to verify any potential biological effects of amylin(1-8), we investigated the efficacy of this peptide in various in vitro assays. Experiments designed to confirm previously published results on the proliferative effects of amylin(1-8) on primary osteoblasts failed to show any response. Amylin(1-8) was able to partially displace (125)I-rat amylin(1-37) from amylin receptors composed of the calcitonin receptor and RAMP1, indicating specific interaction of the peptide with the amylin binding site. However, in vitro efficacy assays with amylin(1-8) in calcitonin receptor-RAMP-positive HEK293T and MCF7 cells failed to reveal any agonist activity of amylin(1-8), whereas amylin(1-37) showed the expected agonist activity. In conclusion, our results indicate that amylin(1-8) does not show agonist activity on amylin receptors, does not affect osteoblast proliferation, and is devoid of anabolic activity in bone.

Enhanced weight loss with pramlintide/metreleptin: an integrated neurohormonal approach to obesity pharmacotherapy

The neurohormonal control of body weight involves a complex interplay between long-term adiposity signals (e.g., leptin), and short-term satiation signals (e.g., amylin). In diet-induced obese (DIO) rodents, amylin/leptin combination treatment led to marked, synergistic, fat-specific weight loss. To evaluate the weight-lowering effect of combined amylin/leptin agonism (with pramlintide/metreleptin) in human obesity, a 24-week, randomized, double-blind, active-drug-controlled, proof-of-concept study was conducted in obese or overweight subjects (N = 177; 63% female; 39 +/- 8 years; BMI 32.0 +/- 2.1 kg/m(2); 93.3 +/- 13.2 kg; mean +/- s.d.). After a 4-week lead-in period with pramlintide (180 microg b.i.d. for 2 weeks, 360 microg b.i.d. thereafter) and diet (40% calorie deficit), subjects achieving 2-8% weight loss were randomized 1:2:2 to 20 weeks of treatment with metreleptin (5 mg b.i.d.), pramlintide (360 microg b.i.d.), or pramlintide/metreleptin (360 microg/5 mg b.i.d.). Combination treatment with pramlintide/metreleptin led to significantly greater weight loss from enrollment to week 20 (-12.7 +/- 0.9%; least squares mean +/- s.e.) than treatment with pramlintide (-8.4 +/- 0.9%; P < 0.001) or metreleptin (-8.2 +/- 1.3%; P < 0.01) alone (evaluable, N = 93). The greater reduction in body weight was significant as early as week 4, and weight loss continued throughout the study, without evidence of a plateau. The most common adverse events with pramlintide/metreleptin were injection site events and nausea, which were mostly mild to moderate and decreased over time. These results support further development of pramlintide/metreleptin as a novel, integrated neurohormonal approach to obesity pharmacotherapy.

Randomized comparison of pramlintide or mealtime insulin added to basal insulin treatment for patients with type 2 diabetes

OBJECTIVE

To compare the efficacy and safety of adding mealtime pramlintide or rapid-acting insulin analogs (RAIAs) to basal insulin for patients with inadequately controlled type 2 diabetes.

RESEARCH DESIGN AND METHODS

In a 24-week open-label, multicenter study, 113 patients were randomly assigned 1:1 to addition of mealtime pramlintide (120 microg) or a titrated RAIA to basal insulin and prior oral antihyperglycemic drugs (OADs). At screening, patients were insulin naive or had been receiving <50 units/day basal insulin for <6 months. The basal insulin dosage was titrated from day 1, seeking fasting plasma glucose (FPG) > or =70-<100 mg/dl. Pramlintide and an RAIA were initiated on day 1 and week 4, respectively. The proportion of patients achieving A1C < or =7.0% without weight gain or severe hypoglycemia at week 24 was the primary end point.

RESULTS

More pramlintide- than RAIA-treated patients achieved the primary end point (30 vs. 11%, P = 0.018) with a similar dose of basal insulin. Pramlintide and an RAIA yielded similar mean +/- SEM values for FPG and A1C at 24 weeks (122 +/- 7 vs. 123 +/- 5 mg/dl and 7.2 +/- 0.2 vs. 7.0 +/- 0.1%, respectively) and similar least squares mean reductions from baseline to end point (-31 +/- 6 vs. -34 +/- 6 mg/dl and -1.1 +/- 0.2 vs. -1.3 +/- 0.2%, respectively). RAIAs but not pramlintide caused weight gain (+4.7 +/- 0.7 vs. +0.0 +/- 0.7 kg, P < 0.0001). Fewer patients reported mild to moderate hypoglycemia with pramlintide than with the RAIA (55 vs. 82%), but more patients reported nausea (21 vs. 0%). No severe hypoglycemia occurred in either group.

CONCLUSIONS

In patients taking basal insulin and OADs, premeal fixed-dose pramlintide improved glycemic control as effectively as titrated RAIAs. The pramlintide regimen sometimes caused nausea but no weight gain and less hypoglycemia.

Twenty-four-hour simultaneous subcutaneous Basal-bolus administration of insulin and amylin in adolescents with type 1 diabetes decreases postprandial hyperglycemia

CONTEXT

The purpose of this study was to examine the effect of continuous sc replacement of amylin and insulin for a 24-h period on glucose homeostasis in adolescents with type 1diabetes.

METHODS

Thirteen adolescents with type 1 diabetes on insulin pump therapy participated in a randomized, controlled, crossover design study comparing continuous sc insulin monotherapy (part A) vs. continuous sc insulin and pramlintide infusion (part B). In part A, basal and bolus insulin infusion was per prescribed home regimen. In part B, the basal insulin infusion was the same as part A, but prandial insulin boluses were reduced by 20%. Basal and prandial bolus pramlintide were administered simultaneously via another pump. All boluses were given as a dual wave.

RESULTS

The study regimen resulted in a 26% reduction in postprandial hyperglycemia as compared to insulin monotherapy (area under the curve, 600 min, 2610 +/- 539 vs. 692 +/- 861 mg/liter . min) (P < 0.008). Glucagon concentrations were suppressed postprandially (P < 0.003) but not in the postabsorptive state, whereas plasma insulin concentrations were unchanged.

CONCLUSIONS

Simultaneous continuous sc pramlintide and insulin infusion has the potential of improving glucose concentrations by way of physiological replacement.

Diabetes distress and its association with clinical outcomes in patients with type 2 diabetes treated with pramlintide as an adjunct to insulin therapy

OBJECTIVE

This study was designed to assess diabetes-related distress and its association with clinical outcomes in patients with type 2 diabetes using basal insulin who were treated with pramlintide.

METHODS

In a 16-week, double-blind, placebo-controlled study 211 patients using insulin glargine with or without oral antidiabetes agents were randomized to addition of pramlintide or placebo. Clinical outcomes (change in A1C, postprandial glucose, daily basal insulin dose, and weight) and during-trial hypoglycemia were assessed, along with the Diabetes Distress Scale (DDS). The DDS assesses overall diabetes distress and four subdomains: regimen distress (RD), emotional burden (EB), interpersonal distress (ID), and physician-related distress (PD). Hierarchical, stepwise multiple regression was used to assess the association of clinical outcomes and during-trial hypoglycemia with DDS score changes during the study.

RESULTS

Pramlintide use was associated with a significant reduction in total DDS and RD, but only among those above the median of distress at baseline. Across treatment groups, reduction in basal insulin dose was linked to a drop in total DDS, RD, EB, and ID, reduction in postprandial glucose was associated with reduced total DDS and ID, and reduction in A1C was associated with reduced EB and RD. PD was not associated with hypoglycemia or any clinical outcome. Reduction in weight and incidence of hypoglycemia were not associated with any DDS measure.

CONCLUSIONS

Pramlintide use reduced diabetes-related distress among those with high levels of distress at baseline, and better clinical outcomes were associated with improvements in several domains of diabetes-related distress. Efforts should be made to enhance these potential benefits of treatment.

Pramlintide reduces the risks associated with glucose variability in type 1 diabetes

BACKGROUND

This study was designed to determine whether pramlintide added to insulin therapy reduced the risks associated with extreme blood glucose (BG) fluctuations in patients with type 1 diabetes.

METHODS

Self-monitored BG (SMBG) records were retrospectively analyzed from a randomized, double-blind, placebo-controlled study of the effects of pramlintide on intensively treated patients with type 1 diabetes. Two groups--pramlintide (n=119), 30/60 microg administered subcutaneously at each meal, or placebo (n=129)--were matched by age, gender, and baseline hemoglobin A1C. Using SMBG, daily BG profiles, BG rate of change, and low and high BG indices (LBGI and HBGI, respectively) measuring the risk for hypoglycemia and hyperglycemia were calculated.

RESULTS

Compared with placebo, pramlintide significantly attenuated the pre- to postprandial BG rate of change (F=83.8, P<0.0001). Consequently, in pramlintide-treated patients, the average post-meal BG (8.4 vs. 9.7 mmol/L [151.2 vs. 174.6 mg/dL]) and postprandial HBGI were significantly lower than placebo (both P<0.0001). Substantial daily BG variation was observed in placebo-treated patients, with most significant hyperglycemia occurring after breakfast and during the night; post-meal BG did not vary significantly throughout the day in pramlintide-treated patients. The reduction in postprandial hyperglycemia in pramlintide-treated patients occurred without increased risk for preprandial hypoglycemia as quantified by the LBGI.

CONCLUSIONS

Risk analysis of the effect of pramlintide treatment demonstrated risk-reduction effects independent of changes in average glycemia, most notably reduced rate and magnitude of postprandial BG fluctuations. These effects were not accompanied by an increased risk of hypoglycemia.

Sustained weight loss following 12-month pramlintide treatment as an adjunct to lifestyle intervention in obesity

OBJECTIVE

To assess long-term weight loss efficacy and safety of pramlintide used at different dosing regimens and in conjunction with lifestyle intervention (LSI).

RESEARCH DESIGN AND METHODS

In a 4-month, double-blind, placebo-controlled, dose-ranging study, 411 obese subjects were randomized to receive pramlintide (six arms: 120, 240, and 360 microg b.i.d. and t.i.d.) or placebo in conjunction with a structured LSI program geared toward weight loss. Of the 4-month evaluable subjects (n = 270), 77% opted to continue preexisting treatment during an 8-month single-blind extension (LSI geared toward weight maintenance).

RESULTS

At month 4, mean weight loss from baseline in the pramlintide arms ranged from 3.8 +/- 0.7 to 6.1 +/- 0.8 kg (2.8 +/- 0.8 kg with placebo). By month 12, initial 4-month weight loss was regained in the placebo group but was maintained in all but the 120-microg b.i.d. group. Placebo-corrected weight loss with 120 microg t.i.d. and 360 microg b.i.d. averaged 3.2 +/- 1.2 kg (3.1 +/- 1.1% body wt) and 3.3 +/- 1.1 kg (3.1 +/- 1.0% body wt), respectively, at month 4 (both P < 0.01; 4-month evaluable n = 270) and 6.1 +/- 2.1 kg (5.6 +/- 2.1% body wt) and 7.2 +/- 2.3 kg (6.8 +/- 2.3% body wt), respectively, at month 12 (both P < 0.01; 12-month evaluable n = 146). At month 12, 40 and 43% of subjects treated with 120 microg t.i.d. and 360 microg b.i.d., respectively, achieved >or=10% weight loss (vs. 12% for placebo). Nausea, the most common adverse event with pramlintide in the 4-month study (9-29% pramlintide vs. 2% placebo), was generally mild to moderate and occurred in <10% of subjects during the extension.

CONCLUSIONS

When used over 12 months as an adjunct to LSI, pramlintide treatment, with low-dose three-times-daily or higher-dose two-times-daily regimens, helped obese subjects achieve greater initial weight loss and enhanced long-term maintenance of weight loss.

Managed care perspective on three new agents for type 2 diabetes

BACKGROUND

Despite effective monotherapy for diabetes, approximately 50% of patients require additional medications after 3 years to achieve target glycosylated hemoglobin (A1C) < 7%. Three new agents, each the first in its therapeutic class with a unique mechanism of action, have been approved for the treatment of type 2 diabetes by the U.S. Food and Drug Administration: pramlintide in March 2005, exenatide in April 2005, and sitagliptin in October 2006.

OBJECTIVE

To review the efficacy and safety of 3 new agents for type 2 diabetes (exenatide and pramlintide by subcutaneous injection and sitagliptin by oral administration) and to define their place in therapy given their relatively high cost and unknown long-term safety and efficacy.

METHODS

A MEDLINE search (1950 to June 2007) for English-language articles of studies in human subjects was conducted using these search terms: type 2 diabetes, exenatide, pramlintide, and sitagliptin. This database was supplemented by systematic reviews and meta-analyses through December 2007 and reference citations from the articles identified in the MEDLINE search.

RESULTS

Exenatide, pramlintide, and sitagliptin have all been shown to have a modest effect on reducing A1C. In several relatively short-term trials (generally 15-30 weeks in duration), exenatide injection has been shown to be safe and effective for patients with type 2 diabetes who are either at the maximum doses of or cannot tolerate metformin, sulfonylurea, and/or thiazolidinedione therapy and need to further decrease A1C by at least 0.5% to 1%. While weight loss of 1.5 kg to 2.5 kg associated with exenatide is modest, this effect is of obvious value in many patients with type 2 diabetes. Nausea is the most notable side effect with exenatide, occurring in up to 50% of patients within the first 8 weeks of therapy but decreasing to 5% to 10% by week 24. In addition, the risk for hypoglycemia increases 4- to 5-fold when used in combination with sulfonylureas. Like exenatide, pramlintide injection reduces A1C by approximately 0.5% to 1%, carries the advantage of modest weight loss (1.5 kg over 1 year), and has a high incidence of nausea. Pramlintide can also result in severe hypoglycemia because of its ability to enhance the effects of insulin, a concern given that it is only indicated for use in combination with insulin. Sitagliptin is an oral agent that can be used alone or in combination with other oral hypoglycemic agents and has been shown to reduce A1C by 0.5% to 0.7%. It has only been studied in short-term studies, to date, so the long-term safety and efficacy are unknown. There is potential for severe allergic and dermatologic reactions with sitagliptin.

CONCLUSIONS

The 3 new agents for the management of type 2 diabetes have been shown to reduce A1C by no more than 1.0%, modest by comparison with insulin and the older oral agents. The 3 newer agents have either modest positive effects on body weight or are weight neutral. The longterm safety and efficacy of the 3 newer agents are unknown, and their cost is considerably higher than the first-line agents, metformin and sufonylureas, which are available by generic name. The newer agents offer treatment options in select patients, although their use should be reserved for patients who are not adequately managed by agents with known longterm efficacy and safety, which are often available at a lower cost.

Pramlintide reduced markers of oxidative stress in the postprandial period in patients with type 2 diabetes

BACKGROUND

The production of oxidative stress as a result of postprandial hyperglycaemia is now recognized as an important contributing factor in the development of diabetes complications. The objective of this study was to examine the effects of pramlintide on plasma concentrations of glucose and several markers of oxidative stress in patients with type 2 diabetes following a standardized meal.

METHODS

This was a randomized, single-blind, placebo-controlled, crossover study conducted at two clinical research centres in the United States. A total of 19 subjects (9 men and 10 women) with type 2 diabetes using mealtime insulin participated in the study. Pramlintide (120 microg), or placebo, and rapid-acting mealtime insulin were administered prior to a standardized meal on two separate study days. Plasma concentrations of glucose, nitrotyrosine (NT), oxidized-LDL cholesterol (OxLDL-C), and total radical trapping parameter (TRAP) were assessed during the 4-h postprandial period.

RESULTS

Compared to placebo, pramlintide treatment reduced postprandial excursions of glucose, NT, and OxLDL-C and protected TRAP from consumption. Correlation analysis revealed positive associations between placebo-corrected glucose incremental AUC(0-4 h) and both NT and OxLDL-C and a negative association between placebo-corrected glucose incremental AUC(0-4h) and TRAP.

CONCLUSIONS

The reduction in postprandial glucose excursions achieved with addition of pramlintide to rapid-acting insulin in type 2 diabetes was associated with a reduction in postprandial markers of oxidative stress.

Combination therapy with amylin and peptide YY[3-36] in obese rodents: anorexigenic synergy and weight loss additivity

Circulating levels of the pancreatic beta-cell peptide hormone amylin and the gut peptide PYY[3-36] increase after nutrient ingestion. Both have been implicated as short-term signals of meal termination with anorexigenic and weight-reducing effects. However, their combined effects are unknown. We report that the combination of amylin and PYY[3-36] elicited greater anorexigenic and weight-reducing effects than either peptide alone. In high-fat-fed rats, a single ip injection of amylin (10 microg/kg) plus PYY[3-36] (1000 microg/kg) reduced food intake for 24 h (P < 0.05 vs. vehicle), whereas the anorexigenic effects of either PYY[3-36] or amylin alone began to diminish 6 h after injection. These anorexigenic effects were dissociable from changes in locomotor activity. Subcutaneous infusion of amylin plus PYY[3-36] for 14 d suppressed food intake and body weight to a greater extent than either agent alone in both rat and mouse diet-induced obesity (DIO) models (P < 0.05). In DIO-prone rats, 24-h metabolic rate was maintained despite weight loss, and amylin plus PYY[3-36] (but not monotherapy) increased 24-h fat oxidation (P < 0.05 vs. vehicle). Finally, a 4 x 3 factorial design was used to formally describe the interaction between amylin and PYY[3-36]. DIO-prone rats were treated with amylin (0, 4, 20, and 100 microg/kg.d) and PYY[3-36] (0, 200, 400 microg/kg.d) alone and in combination for 14 d. Statistical analyses revealed that food intake suppression with amylin plus PYY[3-36] treatment was synergistic, whereas body weight reduction was additive. Collectively, these observations highlight the importance of studying peptide hormones in combination and suggest that integrated neurohormonal approaches may hold promise as treatments for obesity.

Pramlintide improved glycemic control and reduced weight in patients with type 2 diabetes using basal insulin

OBJECTIVE

To assess the efficacy and safety of pramlintide in patients with type 2 diabetes suboptimally controlled with basal insulin.

RESEARCH DESIGN AND METHODS

In a 16-week, double-blind, placebo-controlled study, 212 patients using insulin glargine with or without oral antidiabetes agents (OAs) were randomized to addition of pramlintide (60 or 120 microg b.i.d./t.i.d.) or placebo. Insulin glargine was adjusted to target a fasting plasma glucose concentration of 70-100 mg/dl. One coprimary end point was the change in A1C at week 16. The other coprimary end point was a composite measure of overall diabetes control comprising A1C < or = 7.0% or reduction > or = 0.5%, mean daily postprandial glucose (PPG) increments < or = 40 mg/dl, no increase in body weight, and no severe hypoglycemia. Patients meeting all four conditions at week 16 achieved this end point.

RESULTS

More pramlintide- than placebo-treated patients achieved the composite end point (25 vs. 7%; P < 0.001). Reductions (means +/- SE) in A1C (-0.70 +/- 0.11% vs. -0.36 +/- 0.08%; P < 0.05) and PPG increments (-24.4 +/- 3.6 mg/dl vs. -0.4 +/- 3.0 mg/dl; P < 0.0001) were greater in pramlintide- versus placebo-treated patients, respectively. Glycemic improvements were accompanied by progressive weight loss with pramlintide and weight gain with placebo (-1.6 +/- 0.3 kg vs. +0.7 +/- 0.3 kg; P < 0.0001). No treatment-related severe hypoglycemia occurred.

CONCLUSIONS

Pramlintide improved multiple glycemic parameters and reduced weight with no increase in hypoglycemia in patients with type 2 diabetes who were not achieving glycemic targets with basal insulin with or without OAs.

Pharmacologic management of type 1 diabetes: a review for dentistry

The incidence of diabetes mellitus has increased dramatically in the United States over the last 40 years. In 2006, reported cases of diabetes mellitus increased by 6.0%. The vast majority of these increased cases involve Type 2 diabetes, which is becoming much more common in children, adolescents, and young adults. This article reviews the pharmacological treatments available for Type 1 diabetes, the monitoring necessary for diabetes patients, the regimens of intensive insulin therapy that have replaced conventional therapy, and the complications of insulin therapy. Alternate methods of insulin delivery and options for patients are discussed.

Pramlintide acetate injection for the treatment of type 1 and type 2 diabetes mellitus

BACKGROUND

Amylin is a hormone cosecreted with insulin by the beta cells of the pancreas. It suppresses postprandial glucagon secretion and slows gastric emptying. Pramlintide acetate is an amylin analogue that was approved by the US Food and Drug Administration in March 2005.

OBJECTIVE

This article reviews the current primary literature on the clinical efficacy and tolerability of pramlintide injection in the treatment of type 1 and type 2 diabetes mellitus (DM). Among other topics covered are the pharmacokinetics, pharmacodynamics, and dosing and administration of pramlintide.

METHODS

Pertinent English-language articles were identified through a search of MEDLINE (1966-January 2007), International Pharmaceutical Abstracts (1970-present), Database of Abstracts of Reviews of Effectiveness (1995-January 2007), Cochrane Database of Systematic Reviews (1995-January 2007), and EMBASE Drugs & Pharmacology (1991-1st quarter 2007). The search terms included pramlintide, amylin, gastric emptying, pharmacokinetic, pharmacoeconomic, postprandial hyperglycemia, and glucagon. Articles were selected for review if they described studies having a randomized, double-blind, controlled design and included glycosylated hemoglobin (HbA(1c)) as an end point.

RESULTS

Pramlintide is administered subcutaneously in the abdominal area or thigh immediately before each main meal to achieve maximal reductions in post-prandial glucose excursions. Its C(max) is reached within 20 minutes, and its t(1/2) is 48 minutes. Metabolism is primarily via the kidneys. Pramlintide therapy was associated with inhibition of postprandial glucagon secretion in 24 patients with type 2 DM; prolonged gastric emptying in 11 patients with type 1 DM; a 23% reduction in total energy intake in 11 patients with type 2 DM; and a reduction in markers of oxidative stress in 18 patients with type 1 DM (all, P <- 0.05 vs placebo). In two 52-week studies in patients with type 1 DM, the groups that received pramlintide 30 to 60 microg QID (n = 243), 60 microg TID (n = 164), and 60 microg QID (n = 161) had respective 0.39%, 0.29%, and 0.34% reductions in HbA(1c) and 0.5-, 0.3-, and 0.6-kg reductions in body weight, respectively (all, P < 0.05 vs placebo). In two 52-week studies in patients with type 2 DM, the groups that received pramlintide 120 microg BID (n = 166) and 150 microg TID (n = 144) had respective 0.62% and 0.6% reductions in HbA(1c) and 1.4- and 1.3-kg reductions in body weight (all, P < 0.05 vs placebo). Hypoglycemia, nausea, vomiting, and anorexia were the most frequently reported (>/=10% occurrence) adverse events in patients receiving pramlintide compared with placebo. These events were mild to moderate and occurred more frequently during the first month of therapy.

CONCLUSIONS

Pramlintide therapy was associated with reductions in HbA(1c) and body weight in four 52-week studies in patients with type 1 DM and type 2 DM. Hypoglycemia, nausea, vomiting, and anorexia were the most frequently occurring adverse events, particularly during the first month of therapy. Pramlintide was associated with reductions in measures of oxidative stress, but studies are needed to evaluate the effects of this agent on DM-related complications.

Progressive reduction in body weight after treatment with the amylin analog pramlintide in obese subjects: a phase 2, randomized, placebo-controlled, dose-escalation study

CONTEXT

In previous 1-yr trials, treatment with pramlintide (120 microg), an analog of the beta-cell hormone amylin, induced sustained reductions in A1C and body weight in insulin-using subjects with type 2 diabetes.

OBJECTIVE

To assess the potential of pramlintide as an antiobesity agent, we assessed the weight effect, safety, and tolerability of pramlintide in non-insulin-treated obese subjects with and without type 2 diabetes at doses greater than previously studied.

DESIGN/SETTING

We performed a randomized, double-blind, placebo-controlled, multicenter study.

PATIENTS

A total of 204 obese subjects [80/20% female/male, age 48 +/- 10 yr, and body mass index 37.8 +/- 5.6 kg/m(2) (mean +/- SD)] participated in the study.

INTERVENTION

For 16 wk, without concomitant lifestyle intervention, subjects self-administered pramlintide (nonforced dose escalation < or = 240 microg) or placebo via sc injection three times a day before meals.

MAIN OUTCOME MEASURES

Weight, waist circumference, tolerability, and safety were the main outcome measures.

RESULTS

Pramlintide was generally well tolerated, with 88% of subjects able to escalate to the maximum dose of 240 microg. Withdrawal rates were similar between placebo (25%) and pramlintide-treated subjects (29%). Subjects completing 16 wk of pramlintide treatment experienced placebo-corrected reductions in body weight of 3.7 +/- 0.5% (3.6 +/- 0.6 kg; P < 0.001) and waist circumference (3.6 +/- 1.1 cm; P < 0.01). Approximately 31% of pramlintide-treated subjects achieved > or =5% weight loss (vs. 2% placebo; P < 0.001). More pramlintide than placebo-treated subjects reported improvements in appetite control (72% vs. 31%), weight control (63% vs. 24%), and overall well-being (52% vs. 17%). No unexpected safety signals were observed. The most common adverse event reported was mild, transient nausea. Pramlintide-treated subjects not reporting nausea experienced weight loss similar to those who did (3.6 +/- 0.5% and 3.9 +/- 0.5%, respectively).

CONCLUSION

These results support continued evaluation of pramlintide as a potential treatment for obesity.

Pramlintide treatment reduces 24-h caloric intake and meal sizes and improves control of eating in obese subjects: a 6-wk translational research study

Evidence from rodent studies indicates that the beta-cell-derived neurohormone amylin exerts multiple effects on eating behavior, including reductions in meal size, intake of highly palatable foods, and stress-induced sucrose consumption. To assess the effect of amylin agonism on human eating behavior we conducted a randomized, blinded, placebo-controlled, multicenter study investigating the effects of the amylin analog pramlintide on body weight, 24-h caloric intake, portion sizes, "fast food" intake, and perceived control of eating in 88 obese subjects. After a 2-day placebo lead-in, subjects self-administered pramlintide (180 microg) or placebo by subcutaneous injection 15 min before meals for 6 wk without concomitant lifestyle modifications. Compared with placebo, pramlintide treatment elicited significant mean reductions from baseline in body weight on day 44 (-2.1 +/- 0.3 vs. +0.1 +/- 0.4%, P < 0.001), 24-h caloric intake (-990 +/- 94 vs. -243 +/- 126 kcal on day 3, P < 0.0001; -680 +/- 86 vs. -191 +/- 161 kcal on day 43, P < 0.01), portion sizes, and caloric intake at a "fast food challenge" (-385 +/- 61 vs. -109 +/- 88 kcal on day 44, P < 0.05). Pramlintide treatment also improved perceived control of eating, as demonstrated by a 45% placebo-corrected reduction in binge eating scores (P < 0.01). The results of this translational research study confirm in humans various preclinical effects of amylin agonism, demonstrating that pramlintide-mediated weight loss in obese subjects is accompanied by sustained reductions in 24-h food intake, portion sizes, fast food intake, and binge eating tendencies.

Management of comorbid diabetes and cancer

Diabetes mellitus is a frequent comorbidity of cancer patients. The growing epidemic of diabetes is anticipated to have tremendous impact on health care. Diabetes may negatively impact both cancer risk and outcomes of treatment. Oncology nurses are ideally positioned to identify patients at risk for complications that arise from cancer treatment in the setting of pre-existing diabetes. Additionally, oncology nurses may be the first to identify underlying hyperglycemia/hidden diabetes in a patient undergoing cancer treatment. Strategies for assessment and treatment will be discussed, along with specific strategies for managing hyperglycemia, potential renal toxicity, and peripheral neuropathy. Guidelines for aggressive treatment of hyperglycemia to minimize risks of complications will be reviewed. The role of interdisciplinary care, utilizing current evidence, is crucial to supporting patients and their families as they manage the challenges of facing two life-limiting diseases. Whole-person assessment and individualized treatment plans are key to maximizing quality of life for patients with cancer and diabetes.

Are you up-to-date on diabetes medications?

Learn how the newest weapons in the arsenal of antihyperglycemic drugs can help your patient manage her disease.

Therapies for diabetes: pramlintide and exenatide

The American Diabetes Association currently recommends an A1C goal of less than 7 percent. However, many patients are unable to achieve this goal by using oral drug combinations or diet and exercise, leaving insulin as the only treatment option. In most cases, insulin is initiated later in therapy because of its inconvenience and adverse effects (e.g., weight gain, hypoglycemia, possible role in atherogenesis). Although insulin effectively helps patients attain glucose goals, the search for new agents continues. Two injectable agents, pramlintide and exenatide, were approved in 2005 for the treatment of diabetes. Pramlintide, indicated for use in patients with type 1 and 2 diabetes, is a synthetic analogue of human amylin that acts in conjunction with insulin to delay gastric emptying and inhibit the release of glucagon. Exenatide, a glucagon-like peptide-1 mimetic, has multiple mechanisms for lowering glucose levels, including the enhancement of insulin secretion, and is indicated for use in patients with type 2 diabetes. Clinical trials have shown that both agents reduce, by a statistically significant degree, A1C levels (0.3 to 0.7 percent more than placebo), fasting plasma glucose levels, and body weight (3 to 5 lb [1.4 to 2.3 kg]). No studies have examined their effects on diabetic complications, cardiovascular disease, or overall mortality. Pramlintide and exenatide may help make glycemic goals more attainable.

Pramlintide as an adjunct to insulin in patients with type 2 diabetes in a clinical practice setting reduced A1C, postprandial glucose excursions, and weight

OBJECTIVE

This study was designed to assess the safety and efficacy of pramlintide therapy in patients with type 2 diabetes in a clinical practice setting.

METHODS

In this open-label study, 166 insulin-treated patients with type 2 diabetes added pramlintide therapy (120 microg) during an initiation period in which mealtime insulin was reduced by 30-50%. Insulin doses were subsequently adjusted to optimize glycemic control. Endpoints included safety, as well as change in A1C, postprandial glucose, weight, insulin dose, and patient satisfaction following 6 months of pramlintide treatment.

RESULTS

At 6 months, the change in A1C from baseline (8.3%) was -0.56% (P < 0.05; n = 59). Pramlintide treatment significantly reduced mean postprandial glucose excursions (P < 0.05) and weight (-2.8 kg; P < 0.05; n = 125). Glycemic benefits were achieved with lower mealtime insulin doses (-10.3%; P < 0.05; n = 104). Nausea, primarily mild to moderate, was reported by 29.5% of patients (severe nausea in 2.4%). Rates of severe hypoglycemia were low (0.04 events/patient-year).

CONCLUSIONS

In this uncontrolled, open-label setting, pramlintide initiation while reducing mealtime insulin, followed by insulin dose optimization, resulted in improvements in postprandial glucose excursions and A1C. These improvements in glycemic control were accompanied by weight loss.

Pramlintide in the management of insulin-using patients with type 2 and type 1 diabetes

In patients with diabetes, dysregulation of multiple glucoregulatory hormones results in chronic hyperglycemia and an array of associated microvascular and macrovascular complications. Optimization of glycemic control, both overall (glycosylated hemoglobin [A1C]) and in the postprandial period, may reduce the risk of long-term vascular complications. However, despite significant recent therapeutic advances, most patients with diabetes are unable to attain and/or maintain normal or near-normal glycemia with insulin therapy alone. Pramlintide, an analog of amylin, is the first in a new class of pharmaceutical agents and is indicated as an adjunct to mealtime insulin for the treatment of patients with type 1 and type 2 diabetes. By mimicking the actions of the naturally occurring hormone amylin, pramlintide complements insulin by regulating the appearance of glucose into the circulation after meals via three primary mechanisms of action: slowing gastric emptying, suppressing inappropriate post-meal glucagon secretion, and increasing satiety. In long-term clinical trials, adjunctive pramlintide treatment resulted in improved postprandial glucose control and significantly reduced A1C and body weight compared with insulin alone. The combination of insulin and pramlintide may provide a more physiologically balanced approach to managing diabetes.

Effect of adjunctive pramlintide treatment on treatment satisfaction in patients with type 1 diabetes

OBJECTIVE

To assess the effect of adjunctive pramlintide treatment on treatment satisfaction in patients with type 1 diabetes treated with intensive insulin regimens.

RESEARCH DESIGN AND METHODS

Intensively treated (multiple daily injection [MDI] or continuous subcutaneous insulin infusion [CSII] pump therapy) patients with type 1 diabetes completed a study-specific treatment satisfaction questionnaire following 29 weeks of either placebo (n = 136) or pramlintide (n = 130) treatment in a double-blind, noninferiority pramlintide dose titration trial. End points included patient reported outcomes, their relationship to insulin treatment regimen, A1C, weight, and insulin use.

RESULTS

Pramlintide-treated patients reported greater treatment satisfaction in most questionnaire responses. Treatment satisfaction was similar for pramlintide-treated patients regardless of intensive insulin regimens (MDI versus CSII). Mean A1C was reduced to a similar degree in both pramlintide- (-0.39 +/- 0.07%) and placebo-treated (-0.45 +/- 0.07%) patients. However, pramlintide treatment was associated with reductions in mean body weight (-1.50 +/- 0.33 kg; P < 0.0001) and mealtime insulin use (-19.05 +/- 5.17%; P < 0.005) over 29 weeks, while placebo treatment resulted in weight gain (1.28 +/- 0.25 kg) and a smaller reduction in mealtime insulin use (-2.20 +/- 3.33%).

CONCLUSIONS

Despite similar reductions in A1C, pramlintide treatment resulted in greater treatment satisfaction compared with placebo treatment. This was independent of insulin delivery method.

Pramlintide in the treatment of diabetes

Diabetes treatment has traditionally focused on correcting insulin deficiency with exogenous insulin and oral agents designed to enhance insulin secretion or insulin sensitivity in peripheral tissues. The more recent view of diabetes as a disease that affects multiple hormones in addition to insulin has led to the development of new therapies more broadly aimed at restoring glucose homeostasis by correcting abnormalities in additional glucoregulatory hormones. Pramlintide, a synthetic analogue of the beta-cell hormone amylin, regulates the appearance of glucose in the circulation following meals through several mechanisms of action: slowing gastric emptying, preventing inappropriate postprandial secretion of glucagon and increasing satiety. Long-term studies have demonstrated that pramlintide improves postprandial glucose fluctuations and A1C while reducing insulin dose and body weight. This combination of benefits associated with pramlintide makes it an attractive new treatment option for patients with diabetes. Clinical Trial Registry Numbers: 137-155 open-label clinical trial: NCT00108004 (Pramlintide long-term, placebo-controlled clinical trials were completed prior to the requirement for NCT registry).

Adjunctive Therapy with Pramlintide in Patients with Type 1 or Type 2 Diabetes Mellitus

Uncontrolled diabetes mellitus is associated with both microvascular and macrovascular complications. Despite an array of treatment options available, achievement of euglycemia in most patients with diabetes is still lacking. Pramlintide acetate, a synthetic analog of the human hormone amylin and belonging to a new class of agents, was approved in March 2005 as adjunctive treatment in patients with type 1 or 2 diabetes mellitus. To evaluate the data available on the efficacy and safety of pramlintide, we conducted a search of MEDLINE (January 1966-May 2006) and International Pharmaceutical Abstracts (January 1970-May 2006). Bibliographies of clinical trials were reviewed for additional references. The literature reviewed demonstrated that pramlintide is effective in reducing levels of glycosylated hemoglobin and potentially preventing weight gain. The most commonly reported adverse effects associated with pramlintide were nausea, anorexia, and hypoglycemia. These adverse effects occurred more often during the initiation of therapy and were usually mild to moderate in nature. Whether this therapy is a cost-effective option for patients with type 1 or type 2 diabetes mellitus is yet to be determined.

Pramlintide: A new tool in diabetes management

The amylin analogue pramlintide acts in concert with insulin to regulate glucose metabolism. It reduces postprandial hyperglycemia by suppressing postprandial glucagon secretion, regulating gastric emptying, and reducing food intake. In clinical use, pramlintide reduces postprandial glycemic excursions and improves A(1c) without the weight gain and increased risk of hypoglycemia typically seen with intensification of diabetes therapy.

A double-blind, placebo-controlled trial assessing pramlintide treatment in the setting of intensive insulin therapy in type 1 diabetes

OBJECTIVE

To assess safety, efficacy, and tolerability of pramlintide dose escalation with proactive mealtime insulin reduction, followed by insulin optimization, in patients with type 1 diabetes.

RESEARCH DESIGN AND METHODS

This 29-week, double-blind, placebo-controlled study randomized 296 patients to pramlintide or placebo as an adjunct to insulin. During initiation, pramlintide was escalated from 15 to 60 microg/meal (15-microg increments) with recommended reductions (30-50%) in mealtime insulin. Insulin was subsequently adjusted to optimize glycemic control. End points included safety and change in HbA1c (A1C), postprandial glucose, insulin, weight, and tolerability.

RESULTS

Baseline A1C was 8.1% for both groups and at week 29 had decreased comparably (pramlintide -0.5% [95% CI -0.61 to -0.33]; placebo -0.5% [-0.63 to -0.35]). Pramlintide treatment significantly reduced postprandial glucose excursions (incremental area under the curve [AUC](0-3h): pramlintide -175 +/- 40, placebo -64 +/- 38 mg x h(-1) x dl(-1); P < 0.0005) and weight (pramlintide -1.3 +/- 0.30, placebo +1.2 +/- 0.30 kg; P < 0.0001). At week 29, insulin dose decreased by 28 and 4% in pramlintide- and placebo-treated groups, respectively. Nausea, reported by 63 and 36% of patients in pramlintide and placebo groups (P < 0.01), respectively, was predominately mild to moderate in intensity. Severe hypoglycemia rates were low in both groups (pramlintide 0.57 +/- 0.09, placebo 0.30 +/- 0.06 event rate/patient-year; P < 0.05), with increased rates observed in patients remaining at 30 microg pramlintide.

CONCLUSIONS

Pramlintide dose escalation with reduced mealtime insulin was effective during therapy initiation in patients with type 1 diabetes. While both groups experienced equivalent A1C reductions relative to placebo, pramlintide-treated patients experienced reductions in postprandial glucose excursions and weight, not achievable with insulin therapy alone.

Use of pramlintide: the patient's perspective

Pramlintide is the first new antihyperglycemic agent approved for both type 2 and type 1 diabetes since insulin was developed in the 1920s. It is a synthetic analogue of human amylin, a naturally occurring neuroendocrine hormone synthesized by pancreatic beta cells. Pramlintide helps regulate the rate of glucose appearance and improves glucose control postprandially. This action is accomplished through suppressing inappropriate postprandial glucagon secretion and regulating gastric emptying, and is associated with a feeling of satiety. It is given at mealtimes and is indicated for use in type 2 and type 1 diabetes as an adjunct treatment in patients who use mealtime insulin therapy and who have failed to achieve desired glucose control despite optimal insulin therapy. Pramlintide therapy should only be considered for patients who are receiving ongoing care under the guidance of a health care professional skilled in the use of insulin and supported by services of diabetes educators. Pramlintide is used with insulin and has been associated with an increased risk of insulin-induced severe hypoglycemia, particularly in type 1 diabetes. Appropriate patient selection, careful patient instruction, and insulin dose adjustments help reduce this risk. In type 2 diabetes, pramlintide is initiated at 60 microg and may be increased to 120 microg two to three times daily with meals. In type 1 diabetes, pramlintide is initiated at 15 microg and may be increased to 30 or 60 microg with meals. Mealtime insulin should be reduced by 50% at pramlintide initiation and adjusted as the pramlintide dose is increased. It should be given subcutaneously with an insulin syringe and should not be mixed with insulin. The most commonly reported side effect is mild to moderate nausea with initiation, which is usually transient and short term in nature. Frequent self-monitoring of blood glucose is important during initiation to assist in insulin adjustments. Insulin type, dose, and timing as well as basal/bolus balance may require adjustment during pramlintide initiation. Despite requiring additional injections, patients report satisfaction with pramlintide therapy.

Therapeutic options in development for management of diabetes: pharmacologic agents and new technologies

OBJECTIVE

To review new pharmacologic therapies and technologies relevant to the management of diabetes and its complications.

METHODS

New treatment options for diabetes, made available through research efforts during the past 2 decades, are discussed.

RESULTS

Several new drugs and drug classes for the management of diabetes are under development, including the incretin mimetic agents (exenatide, dipeptidyl peptidase 4 inhibitors, and glucagon-like peptide 1 analogues), the amylin analogue pramlintide, the cannabinoid-1 receptor antagonist rimonabant, the mixed peroxisome proliferator-activated receptor agonists muraglitazar and tesaglitazar, the inhaled insulin preparation Exubera, and the insulin analogues (insulin glulisine and insulin detemir).

CONCLUSION

New drugs and technologic advances being made available will help achieve the goals of treating patients with diabetes to all the appropriate metabolic targets. Many other agents that act on fundamental abnormalities such as energy imbalance, inflammation, and vascular biologic conditions are in very early stages of development but are likely to become available during the next 5 to 10 years.

The role of amylin and related peptides in osteoporosis

Osteoporosis is a systemic skeletal disorder that remains a major public health problem due to significant fracture-associated morbidity and mortality. Because it has been shown that individuals having type I diabetes mellitus also suffer from osteopenia or osteoporosis, there is probably a pathophysiological mechanism that links pancreatic beta cell insufficiency with inappropriate bone formation. Many factors have been suggested, including amylin, a product of pancreatic beta cells with structural and functional similarity to calcitonin. Amylin has been shown to stimulate bone development via action on osteoblasts and osteoclasts. Recently, amylin receptors have been identified as complexed calcitonin receptor with receptor activity modifying proteins. Moreover, a synthetic amylin analogue (pramlintide) has been developed for clinical use. These findings including results from in vitro animal and human studies suggest a role for amylin as a potential diagnostic and therapeutical tool in patients with various bone diseases including osteoporosis. However, other structurally and functionally related hormones that affect bone metabolism should also be taken in account including calcitonin, calcitonin gene-related peptide and adrenomedullin.