Continuous subcutaneous pump infusion of somatostatin analogue SMS 201-995 versus subcutaneous injection schedule in acromegalic patients

Novel Somatostatin Receptor Ligands Therapies for Acromegaly

Surgery is considered the treatment of choice in acromegaly, but patients with persistent disease after surgery or in whom surgery cannot be considered require medical therapy. Somatostatin receptor ligands (SRLs) octreotide (OCT), lanreotide, and the more recently approved pasireotide, characterized by a broader receptor ligand binding profile, are considered the mainstay in the medical management of acromegaly. However, in the attempt to offer a more efficacious and better tolerated medical approach, recent research has been aimed to override some limitations related to the use of currently approved drugs and novel SRLs therapies, with potential attractive features, have been proposed. These include both new formulation of older molecules and new molecules. Novel OCT formulations are aimed in particular to improve patients' compliance and to reduce injection discomfort. They include an investigational ready-to-use subcutaneous depot OCT formulation (CAM2029), delivered via prefilled syringes and oral OCT that uses a "transient permeability enhancer" technology, which allows for OCT oral absorption. Another new delivery system is a long-lasting OCT implant (VP-003), which provide stable doses of OCT throughout a period of several months. Finally, a new SRL DG3173 (somatoprim) seems to be more selective for GH secretion, suggesting possible advantages in the presence of hyperglycemia or diabetes. How much these innovations will actually be beneficial to acromegaly patients in real clinical practice remains to be seen.

Octreotide for acromegaly treatment: a reappraisal

INTRODUCTION

Acromegaly is a rare disorder characterized by excess secretion of growth hormone (GH) generally caused by a pituitary macroadenoma and associated with reduced life expectancy if the disease is untreated. This article covers the recent available evidences published on octreotide , the first somatostatin analog introduced into clinical practice for the medical treatment of acromegaly.

AREAS COVERED

This article discusses i) pharmacology of somatostatin and octreotide; ii) biochemical effects of regular octreotide and long-acting repeatable formulation; iii) tumor shrinkage effects of octreotide in acromegaly; iv) impact of octreotide on acromegalic clinical manifestations and chronic complications; v) safety of octreotide and vi) place of octreotide in the guidelines for acromegaly treatment. Full-text articles in the English language were selected from a PubMed search spanning 1984 - 2013, for keywords including 'octreotide,' 'acromegaly,' 'GH,' 'IGF-I,' and 'tumor shrinkage.' Reference lists in selected papers were also used to broaden the search.

EXPERT OPINION

Octreotide is a mature drug with a consolidated favorable benefit versus risks profile in the treatment of acromegaly.

Octreotide LAR: safety and tolerability issues

BACKGROUND

Somatostatin analogues are the cornerstone in therapy of acromegaly and functioning neuroendocrine tumors. Long-acting retard formulations have improved patient survival and contributed considerably to quality of life. The first such compound was octreotide LAR ('long-acting release'), characterized by high affinity to somatostatin receptor subtypes 2 and 5, which has to be injected intramuscularly every 4 weeks.

OBJECTIVE

The aim was to screen all octreotide LAR-related literature and assess the compound's profile for safety and tolerability.

METHODS

An extensive literature search has been performed using the MEDLINE database to retrieve data from clinical studies evaluating the efficacy and tolerability of octreotide LAR.

RESULTS/CONCLUSION

Octreotide LAR is well tolerated; however, diarrhea and gallstone formation were identified as the main adverse events. Impairment of glucose homeostasis was a regular phenomenon, but its occurrence was unpredictable. General side effects such as headache, abdominal discomfort or fatigue were also reported. According to incidental case reports, administration during pregnancy appears to be safe for both mother and child; however, definitive evidence is missing. In addition, octreotide LAR has been evaluated for further indications including treatment of solid tumor entities, due to its antiproliferative effect. Currently, several compounds (lanreotide, SOM230) with a broader receptor spectrum are under evaluation and may improve treatment efficacy and lower incidence of side effects.

Pegvisomant Treatment in a 4-Year-Old Girl with Neurofibromatosis Type 1

BACKGROUND/AIMS

Growth hormone (GH) excess in childhood is a rare disorder. Current treatment options such as somatostatin analogues, pituitary surgery or irradiation can have serious side effects. Recently, a GH receptor antagonist, pegvisomant, was introduced for the treatment of adults with acromegaly. We wanted to investigate whether pegvisomant was effective in a child with octreotide-resistant GH excess.

CASE

A 4-year-old girl with neurofibromatosis type 1 and GH excess associated with optic glioma received pegvisomant injections (10 mg subcutaneously) with increasing intervals from daily to every 4th day.

RESULTS

IGF-I and IGFBP-3 decreased from +6.9 and 4.6 standard deviation scores (SDS), respectively, to within normal range. Height velocity dropped from 12.4 SDS to mean -0.7 SDS (range: -5.0 to 5.0) and height SDS decreased from +1.3 to +0.6 (target height: +0.2). Random non-fasting serum GH values were mean 5.0 mlU/l (range: 1.6-9.5). There was no change in fasting blood glucose (4.6-4.7 mmol/l) or glycosylated haemoglobin (5.5%) and no subjective or biochemical side effects. Repeated tests of thyroid, adrenal and gonadal function showed no alterations during the treatment period. Intracranial tumours remained unchanged in size and visual impairment did not deteriorate.

CONCLUSION

Pegvisomant normalized IGF-I and IGFBP-3 levels. Growth velocity was normalized after initial catch-down growth, and it remains to be seen whether this result can be maintained during long-term treatment.

Neuroendocrine tumors secreting growth hormone-releasing hormone: Pathophysiological and clinical aspects

Hypothalamic GHRH is secreted into the portal system, binds to specific surface receptors of the somatotroph cell and elicits intracellular signals that modulate pituitary GH synthesis and/or secretion. Moreover, GHRH is synthesized and expressed in multiple extrapituitary tissues. Excessive peripheral production of GHRH by a tumor source would therefore be expected to cause somatotroph cell hyperstimulation, increased GH secretion and eventually pituitary acromegaly. Immunoreactive GHRH is present in several tumors, including carcinoid tumors, pancreatic cell tumors, small cell lung cancers, endometrial tumors, adrenal adenomas, and pheochromocytomas which have been reported to secrete GHRH. Acromegaly in these patients, however, is uncommon. The distinction of pituitary vs. extrapituitary acromegaly is extremely important in planning effective management. Regardless of the cause, GH and IGF-1 are invariably elevated and GH levels fail to suppress (<1 microg/l) after an oral glucose load in all forms of acromegaly. Dynamic pituitary tests are not helpful in distinguishing acromegalic patients with pituitary tumors from those harbouring extrapituitary tumors. Plasma GHRH levels are usually elevated in patients with peripheral GHRH-secreting tumors, and are normal or low in patients with pituitary acromegaly. Unique and unexpected clinical features in an acromegalic patient, including respiratory wheezing or dyspnea, facial flushing, peptic ulcers, or renal stones sometimes are helpful in alerting the physician to diagnosing non pituitary endocrine tumors. If no facility to measure plasma GHRH is available, and in the absence of MRI evidence of pituitary adenoma, a CT scan of the thorax and abdominal ultrasound could be performed to exclude with good approximation the possibility of an ectopic GHRH syndrome. Surgical resection of the tumor secreting ectopic GHRH should be the logical approach to a patient with ectopic GHRH syndrome. Standard chemotherapy directed at GHRH-producing carcinoid tumors is generally unsuccessful in controlling the activated GH axis. Somatostatin analogs provide an effective option for medical management of carcinoid patients, especially those with recurrent disease. In fact, long-acting somatostatin analogs may be able to control not only the ectopic hormonal secretion syndrome, but also, in some instances, tumor growth. Therefore, although cytotoxic chemotherapy, pituitary surgery, or irradiation still remain available therapeutic options, long-acting somatostatin analogs are now preferred as a second-line therapy in patients with carcinoid tumors and ectopic GHRH-syndrome.

Growth hormone receptor antagonists: discovery, development, and use in patients with acromegaly

An understanding of the events that occur during GH receptor (GHR) signaling has facilitated the development of a GHR antagonist (pegvisomant) for use in humans. This molecule has been designed to compete with native GH for the GHR and to prevent its proper or functional dimerization-a process that is critical for GH signal transduction and IGF-I synthesis and secretion. Clinical trials in patients with acromegaly show GHR blockade to be an exciting new mode of therapy for this condition, and pegvisomant may have a therapeutic role in diseases, such as diabetes and malignancy, in which abnormalities of the GH/IGF-I axis have been observed. This review charts the discovery and development of GHR antagonists and details the experience gained in patients with acromegaly.

The place of pegvisomant in the management of acromegaly

Conventional treatments for acromegaly include surgery, radiotherapy, dopamine agonists and somatostatin (SMS) analogues, which effect disease control by lowering circulating growth hormone (GH). Due to variability in tumour characteristics, combinations of these treatment modalities leave a significant number of patients with sub-optimal serum GH and insulin-like growth factor-I (IGF-I) levels, which have been linked to increased morbidity and mortality. The GH receptor antagonist pegvisomant is a genetically engineered analogue of GH that prevents functional dimerisation of the growth hormone receptor (GHR); a process that is critical to GH action at the cellular level. A crucial amino acid substitution at Gly(120) to Arg(120) within the third alpha helix of the antagonist prevents functional GHR dimerisation. Pegvisomant represents a novel treatment for acromegaly as, unlike existing treatment modalities, the effectiveness of pegvisomant is independent of pituitary tumour characteristics. Initial clinical studies in patients with active acromegaly have demonstrated serum IGF-I normalisation in over 90% of patients receiving 20 mg per day, such that, in terms of serum IGF-I normalisation, pegvisomant now represents the most effective medical treatment for acromegaly. Although there are limited long-term data on the use of pegvisomant and questions regarding pituitary tumour growth and altered liver function remain, this therapy offers the prospect of serum IGF-I normalisation in the vast majority of patients with active acromegaly.

Evaluation of the treatment of thyrotropin-secreting pituitary adenomas with a slow release formulation of the somatostatin analog lanreotide

Somatostatin analogs have been shown to be effective for the treatment of TSH-secreting pituitary adenomas. However, their use in this indication is limited by the fact that available analogs require several daily sc injections. The present study was performed to evaluate the effects of a slow release formulation of the somatostatin analog lanreotide (SR-L) on both hormone secretion and tumor size and to assess the tolerance in a series of thyrotropinomas treated for 6 months. Eighteen patients with hyperthyroidism related to a TSH-secreting pituitary adenoma, evidenced by pituitary magnetic resonance imaging, were studied. After a basal assessment, each patient received 30 mg SR-L, im, every 14 days for 1 month. Then, according to the free T3 (fT3) plasma level measured, 9 of 18 patients were injected twice monthly, and 7 of 18 patients received SR-L every 10 days for 5 additional months. One patient was dismissed from the study in month 1 of the study for side-effects and another in month 3 for noncompliance to the protocol. Clinical and biological evaluations (plasma TSH, free alpha-subunit, fT4, fT3, and lanreotide levels) were performed before and in months 1, 3, and 6 of treatment. Pituitary magnetic resonance imaging and gallbladder ultrasonography were performed both at entry and at the end of the study. Clinical signs of hyperthyroidism improved within 1 month in all 16 evaluable patients. Mean (+/- SEM) plasma lanreotide levels reached 1.11 +/- 0.43 and 1.69 +/- 0.65 ng/mL in month 3 using 2 and 3 injections/month, respectively, then remained stable until the end of the study. During therapy, the plasma TSH level decreased from 2.72 +/- 0.32 to 1.89 +/-0.27 mU/L (P < 0.01), with parallel significant changes in free alpha-subunit. During the same period, plasma fT4 and fT3 levels decreased from 37.9 +/- 2.9 to 19.7 +/- 2.3 pmol/L (P < 0.01) and from 14.6 +/- 1.1 to 8.3 +/- 0.8 pmol/L (P < 0.01), respectively. No statistically significant change in mean adenoma size was observed after 6 months of treatment. Side-effects, including pain at the injection point, abdominal cramps, and diarrhea, were mild and transient and did not lead to interruption of the treatment. No gallstones occurred during the study. SR-L appears to be able to suppress clinical signs of hyperthyroidism in our series of patients with TSH-secreting pituitary adenomas. The analog also reduces plasma TSH and thyroid hormone levels, which were normalized in 13 of 16 cases. The effect was maintained throughout the treatment using 2 or 3 SR-L injections monthly without any problem of tolerance. We conclude that SR-L is a safe and effective treatment of thyrotropinomas and avoids the drawbacks of the modes of administration of other somatostatin analogs, given three times daily.

Effects of a 7-day continuous infusion of octreotide on circulating levels of growth factors and binding proteins in growth hormone (GH)-treated GH-deficient patients

In patients with acromegaly, clinical improvement has been reported after octreotide (OCT) treatment, even in cases of only a moderate suppression of growth hormone (GH) levels. In rats, OCT suppresses IGF-I mRNA expression and generation of serum and tissue IGF-I levels. A direct effect of OCT on the IGF system could have therapeutical implications in diabetes mellitus, cardiovascular disease, and certain malignancies in which IGF-I might be involved. The aim of this study was to examine possible GH-independent effects of OCT on IGF components in humans. Six GH-deficient (GHD) patients were studied for 24 h after each of the following treatment regimens (each of 1 weeks duration): (a) daily s.c. GH injection (2 IU/m(2)); (b) as (a) + continuous s.c. infusion of OCT (200 microg/24 h) by means of a portable pump (Nordic Infuser); (c) no treatment. Serum GH binding protein (GHBP) levels tended to be lower after GH and OCT than after GH alone (P =0.10). OCT reduced the GH induced increase in serum IGF-I levels (P<0.05, ANOVA). Mean integrated levels (microg/l) were 359.1+/-49.6 (GH), and 301.6+/-58.9 (GH+OCT). OCT did not significantly reduce serum IGFBP-3 levels (microg/l) [3460+/-270 (GH), and 3112+/-435 (GH+/-OCT);P =0.14]. Serum levels of free IGF-I (P =0.39), IGF-II (P =0.54), and of the acid-labile subunit (ALS) of the ternary complex (P =0.50) were similar during GH+/-OCT as compared with GH alone. After 1 week off GH treatment, significantly lower levels of IGF-I, IGF-II, IGFBP-3, and ALS were recorded (P<0.001). Serum IGFBP-1 levels were significantly higher after GH+OCT than after GH alone (P<0.0001), and levels were even higher without GH. Serum insulin levels (pmol/l) were significantly higher after GH alone as compared with no GH (P<0.05, ANOVA), whereas OCT partly suppressed the insulinotropic effect of GH (P<0. 05) [mean: 114.5+/-33.0 (GH), 91.3+/-29.6 (GH+OCT), 65.9+/-22.5 (no GH)]. This was also reflected in higher blood glucose levels during GH+OCT. Finally, GH+OCT reduced glucagon levels significantly as compared with GH alone (P =0.02). In conclusion, 7 days' administration of OCT to GH-treated GHD patients slightly attenuated serum IGF-I generation, and tended to decrease levels of the other components of the 150 kDa ternary complex. Whether these effects are mediated directly by OCT or indirectly via the accompanying changes in insulin levels remains to be investigated.

Cardiovascular effects of a single slow release lanreotide injection in patients with acromegaly and left ventricular hypertrophy

In our study we assessed the effects of a single i.m. injection of slow-release Lanreotide (30 mg) (SR-L), a new long-acting somatostain analog, on circulating GH levels, baseline cardiac function (M-mode, 2D guided, doppler-echocardiographic study) and cardiopulmonary response to exercise (cycloergometric test, performed using a computer drived, electrically braked cycle ergometer), tested at baseline, after 7 and 14 days from the injection in 10 acromegalic patients (5 M, 5 F, mean age 57.7 +/- 3.1 yrs, body mass index (BMI) 27 +/- 0.8 kg/m2, blood pressure 141 +/- 6.5/82 +/- 3 mmHg). SR-L administration decreased GH levels in acromegalic patients (mean +/- SEM) from 16.1 +/- 6.9 to 10.8 +/- 5.1 micrograms/L (p = 0.045) after 7 days and to 11.9 +/- 5 micrograms/L (p = 0.078) after 14 days from the injection. Moreover, we observed a significant (p < 0.05) decrease in systolic blood pressure and heart rate at the 7th (135 +/- 6.1 vs 141 +/- 6.5 mmHg, and 68 +/- 2.1 vs 74 +/- 2.1 bpm) and 14th (137 +/- 6.2 vs 141 +/- 6.5 mmHg, and 72 +/- 2 vs 74 +/- 2.1 bpm) day of the study with respect to the baseline values. After SR-L administration we also found an increase in ejection fraction (69 +/- 2 vs 63 +/- 2.3% at 7th day, p = 0.006; 65 +/- 2.3 vs 63 +/- 2.3% at the 14th day, p = 0.027) and shortening fraction (40.8 +/- 1.8 vs 36.6 +/- 1.9% at 7th day, p = 0.005; 38.7 +/- 1.8 vs 36.6 +/- 1.9% at the 14th day, p = 0.045). The positive acute cardiac response to SR-L injection was also demonstrated by the increase in A/E velocity ratios at 7th (1.14 +/- 0.1 vs 0.98 +/- 0.07, p = 0.016) and 14th (1.04 +/- 0.08 vs 0.98 +/- 0.07, p = 0.008) day of the study. After SR-L injection, exercise capacity and VO2 at anaerobic threshold were also increased with respect to the baseline test: 61.1 +/- 8.2 vs 38.9 +/- 6.8 watts (p = 0.002) and 1012.4 +/- 71.5 vs 915.3 +/- 77.8 mL/min (p = 0.033) after 7 days, and 61.4 +/- 7.2 vs 38.9 +/- 6.8 watts (p = 0.002) and 1010.1 +/- 62.5 vs 915.3 +/- 77.8 mL/min (p = 0.010) after 14 days from the injection. In conclusion, these results suggest that in acromegalic patients: (1) SR-L causes a rapid improvement in baseline cardiac function and in cardiopulmonary performance during exercise in acromegaly; (2) the endocrine (decrease in GH levels) and echocardiographic responses to SR-L are maximal after 7 days from the injection, whereas the effect of SR-L on the exercise performance are longer lasting.

The future of somatostatin analogue therapy

Since its discovery almost 30 years ago, the mode of action and therapeutic applications of somatostatin have been defined. In particular the cloning and characterization of somatostatin receptor subtypes has facilitated the development of high affinity analogues. In the context of pituitary disease, long-acting somatostatin analogues (octreotide, lanreotide) have been used to treat a variety of pituitary tumours but are most efficacious for the treatment of GH and TSH-secreting adenomas. In patients with acromegaly, depot preparations of these analogues are administered intramuscularly every 10-28 days and provide consistent suppression of GH levels to < 5 mU/l in approximately 50-65% of all cases. Even more specific somatostatin receptor analogues are under development. Finally, radiolabelled somatostatin analogue scintigraphy and, in larger doses, therapy, are now established tools in the evaluation and treatment of neuroendocrine tumours.

Comparison of monthly intramuscular injections of Sandostatin LAR with multiple subcutaneous injections of octreotide in the treatment of acromegaly; effects on growth hormone and other markers of growth hormone secretion

OBJECTIVE

To compare the effects of monthly intra-muscular injections of a long acting preparation of octreotide, Sandostatin LAR, with multiple daily subcutaneous injections of octreotide and to study the interrelationships between mean 24 h growth hormone profile, serum total and free IGF-1 levels, 24 h urinary growth hormone levels and serum IGFBP-3.

DESIGN

Patients were assessed by 24 h GH profile off octreotide or any other GH modifying drug therapy; on subcutaneous octreotide (200-600 micrograms daily in divided doses for six weeks); and 28 days after the second of two injections of Sandostatin LAR (20 mg by intra-muscular injection) administered 28 days apart. Serum total and free IGF-1, serum IGFBP-3 and 24 h urinary GH were also measured on each occasion.

RESULTS

Sandostatin LAR was well tolerated. None of the patients reported any adverse effect and all completed the study uneventfully. Mean GH off treatment was 10.1 +/- 3.0 micrograms/l falling equally significantly (P < 0.05) during therapy with subcutaneous octreotide to 3.0 +/- 0.7 micrograms/l and Sandostatin LAR to 2.8 +/- 0.7 micrograms/l. Fasting 0900 h GH was significantly reduced (P < 0.05) on Sandostatin LAR (3.0 +/- 0.7 micrograms/l) compared with subcutaneous octreotide (5.1 +/- 1.2 micrograms/l). Mean total IGF-1 off treatment was 658.6 +/- 56.1 micrograms/l and was reduced to a comparable extent with subcutaneous octreotide and Sandostatin LAR (466.0 +/- 59.7 and 448.6 +/- 59.5 micrograms/l respectively; both P < 0.05). Free IGF-1 off treatment was 3.1 +/- 0.6 micrograms/l and was reduced equally by subcutaneous octreotide and Sandostatin LAR (1.2 +/- 0.2 and 1.2 +/- 0.2 micrograms/l; both P < 0.05). IGFBP-3 was reduced to a greater extent during Sandostatin LAR than during subcutaneous octreotide (4518.2 +/- 247.3 vs 5132.8 +/- 280.7 micrograms/l; P < 0.05). Twenty-four hour urinary GH excretion was reduced to a comparable extent with both therapies. Highly significant positive correlations were found between mean 24 h GH levels and free IGF-1 (r = 0.66, P < 0.0001) and 24 h urinary GH excretion (r = 0.94, P < 0.0001). The relationships between mean 24 h GH levels and total IGF-1 and IGFBP-3 although significant showed less powerful correlations.

CONCLUSIONS

These results suggest that Sandostatin LAR is well tolerated and as effective as subcutaneous octreotide. In addition, urinary growth hormone and serum free IGF-1 may prove valuable for outpatient follow-up of acromegalic patients, as both correlate well with mean 24 h serum growth hormone levels.

Suppression of GH secretion in pituitary gigantism by continuous subcutaneous octreotide infusion in a pubertal boy

We describe a 12-y-old boy with excessive growth hormone and prolactin secretion presumably due to diffuse somatotroph hyperplasia. Until mid-puberty, his growth rate was under reasonable control, with high-dose octreotide injections every 8 h combined with a dopamine agonist. As his growth velocity started to increase, the efficacy of continuous s.c. octreotide infusion on GH secretion was tested. Similar total daily doses (600 microg) of octreotide were administered either by incremental s.c. injections at 8 h intervals, or by continuous s.c. infusion, two-thirds of the amount during night-time to control the presumed high nocturnal growth hormone (GH) peaks of the pubertal growth spurt. An overnight GH profile showed inadequate suppression of GH levels by incremental injections, while continuous s.c. infusion efficiently brought down the GH secretion. Another somatostatin analogue, lanreotide as a single depot injection was not effective. A 6-mo trial on the s.c. infusion regimen significantly reduced growth hormone secretion (as judged by IGF-I and IGFBP3 concentrations), and normalized growth velocity overcoming the pubertal growth spurt. It also caused a decrease in the pituitary size in magnetic resonance images. We conclude that the efficacy of octreotide infusion in suppressing GH secretion is superior to incremental injections with the same dose.

Results of a European multicentre study with Sandostatin LAR in acromegalic patients. Sandostatin LAR Group

A European multicentre, open-label 12-month study with Sandostatin LAR administered intramuscularly at 4-week intervals was initiated in 151 acromegalics responsive to octreotide. All patients received 3 injections of the 20 mg dose, following which the dose was adjusted to 10 mg in patients with mean 4-hour GH serum concentrations below 1 microgram/L (N: 29) and to 30 mg in patients with concentrations above 5 micrograms/L (N: 22). The GH level suppression was significant in the 20 mg dose group (p < 0.01) and for all 151 patients (p < 0.004), and was consistently maintained in all patients for the duration of the study. The suppression of the mean serum GH concentration to below 2.5 micrograms/L was recorded in 69.8% of patients at the endpoint treatment with Sandostatin LAR and 65.8% during prior treatment with Sandostatin s.c. A consistent suppression of serum IGF-I levels was also achieved. The number of patients with headache, fatigue, perspiration, joint pains and paresthesias had decreased significantly (p < 0.05) after the 6t]h injection of Sandostatin LAR vs. previous s.c. treatment. No patient discontinued the study because of drug-related adverse events. The most frequently reported adverse events were mild diarrhea, abdominal pain and flatulence. The local tolerability was very good. No impairment of safety hematology, biochemistry and thyroid function tests and no increased incidence of gallstone formation was recorded. Well tolerated and at least as efficacious as the s.c. formulation, Sandostatin LAR might become an alternative primary treatment to pituitary surgery and radiotherapy.

Different effects of octreotide by continuous night infusion at increasing rate or by evening injections at different times on morning hyperglycemia and growth hormone levels in insulin-dependent diabetic patients

The effect of octreotide on morning hyperglycemia and GH levels was evaluated in eight insulin-dependent diabetic patients. Octreotide (50 mcg) was administered through subcutaneous injections at different hours (20:00, 22:00 and 24:00 h) or through continuous subcutaneous night infusion from midnight to 08:00 at increasing rate between 03:00 and 08:00 h. After octreotide injection at midnight we noticed a sharp decrease of both glycemia (p < 0.005) and GH (p < 0.05) at 04:00 h, but not at 08:00 h. Only the night continuous infusion at increasing rate was able to reduce glycemia and GH at 04:00 and at 08:00 h (p < 0.001 and p < 0.01 respectively). The injections of octreotide at 20:00 and 22:00 h lowered GH values at 24:00 h (p < 0.01 and p < 0.05 vs insulin alone) but did not show any significant effect on blood glucose levels and GH at 04:00 and 08:00 h. In conclusion, only the continuous subcutaneous night infusion of octreotide at increasing rate during the last hours of the night was able to reduce simultaneously morning hyperglycemia and GH levels in insulin-dependent diabetic patients, whereas evening subcutaneous injections at different times did not show any appreciable effect.

Long-term therapy with long-acting octreotide (Sandostatin-LAR) for the management of acromegaly

OBJECTIVES

To evaluate the efficacy and safety of a long-acting preparation of the somatostatin analogue octreotide, Sandostatin-LAR (SMS-LAR) for the treatment of acromegaly.

DESIGN AND PATIENTS

Thirteen patients with acromegaly received intramuscular injections of SMS-LAR 20-40 mg at 4-6 week intervals for a period of up to 3 years.

MEASUREMENTS

Serial measurement of serum GH and IGF concentrations were obtained. Symptoms related to acromegaly were scored by patients at baseline and following each injection. Serial gallbladder ultrasound and pituitary imaging was performed throughout the study.

RESULTS

One patient was withdrawn from the study after 6 months because of continued gastrointestinal side effects; 4 patients were treated with monthly injections for 12 months and 8 patients with injections at either 1 month or 6-week intervals for 36 months; hence data is presented for n = 12 for up to 12 months; and thereafter n = 8. SMS-LAR significantly reduced serum GH and IGF-1 values: for the whole group GH concentrations fell from 24.8 +/- 4.2 mU/l (mean +/- SE) at baseline to 5.2 +/- 0.8 mU/l at 12 months (P < 0.01, n = 12). In the 8 patients treated for 3 years GH fell from 27.8 +/- 6.1 mU/l at baseline to 4.2 +/- 0.8 mU/l at the end of 3 years (P < 0.01, n = 8). GH fell to < 10 mU/l in all subjects and was < 5 mU/l in 50% after both 1 and 3 years. IGF-1 concentrations fell from 95 +/- 13 nmol/l at baseline to 63 +/- 13 nmol/l after 1 year (P < 0.01, n = 12; reference range < 65 nmol/l). In the 8 patients treated for 3 years IGF-1 concentrations fell from 119 +/- 14 nmol/l at baseline to 60 +/- 13 nmol/l after 3 years (P < 0.001, n = 8). IGF-1 was < 65 nmol/l in 60% of patients after 1 year and 75% after 3 years. Treatment resulted in trends towards improvement in symptoms of acromegaly and statistically significant improvement in sweating. There was no evidence of tachyphylaxis or evidence to suggest development of glucose intolerance. Only 2 patients (15%) developed gallbladder sludge which was asymptomatic; no patient developed gallstones.

CONCLUSIONS

We conclude that SMS-LAR is a safe, effective and well tolerated treatment, making it an important therapeutic option in the management of acromegaly.

One- and three-month release injectable microspheres of the LH-RH superagonist leuprorelin acetate

The biodegradable polymers poly(lactic/glycolic acid) (PLGA) and poly(lactic acid) (PLA) were used as wall materials in the preparation of microspheres (msp) containing the LH-RH superagonist leuprorelin (leuprolide) acetate. A novel W/O/W emulsion-solvent evaporation method was devised for the preparation of msp containing this water-soluble peptide. This method achieved high entrapment efficiency and sustained drug release over a long period predominantly due to polymer bioerosion. The msp are fine microcapsules with polycores containing the peptide at a high concentration and are easily injectable through a conventional fine needle. Leuprorelin msp made with PLGA(75/25)-14,000 or PLA-15,000 released the drug in a zero-order fashion, maintained constant serum drug levels and attained persistent objective suppression of the pituitary-gonadal system ('chemical castration') over 1 or 3 months after i.m. or s.c. injection into animals. These results indicate that depot formulations may be potentially useful in the therapy of endocrine diseases in humans. In this paper, studies on the formulation, drug release and pharmacological effects in animals for these leuprorelin depot formulations are reviewed.

Effects of the somatostatin analog, octreotide, on glucose metabolism and insulin sensitivity in insulin-dependent diabetes mellitus

To examine the effect of the somatostatin analog, octreotide, on insulin-mediated glucose uptake, seven insulin-dependent diabetic (IDDM) subjects were studied with and without 4 days of continuous subcutaneous octreotide administration (1 mg/kg/d). Insulin dosage was adjusted after frequent measurements of plasma glucose level. On the third day a hormonal and metabolic blood profile was obtained, and on the fourth day a euglycemic (5 mmol/L), hyperinsulinemic (1 mU/kg/min) clamp was performed in combination with calorimetry and a muscle biopsy. Mean plasma glucose levels on day 3 were similar (7.9 +/- 0.9 v 9.0 +/- 0.6 mmol/L). Growth hormone (GH) (0.39 +/- 0.10 v 0.78 +/- 0.23 mg/L, P < .05), insulin-like growth factor-1 (IGF-1) (127 +/- 17 v 157 +/- 21 mg/L, P < .05), and nonesterified fatty acids (NEFA) (239 +/- 25 v 405 +/- 44 mmol/L, P < .01) were lower following octreotide administration. Insulin requirements were reduced during octreotide administration, resulting in significantly lower insulin levels (27.3 +/- 2.7 v 39.9 +/- 9.9 mU/L, P < .5). During the clamp, glucose and insulin levels wer similar. Following octreotide, glucose disposal (7.33 +/- 0.49 v 6.08 +/- 0.55 mg/kg/min, P < .05) increased and hepatic glucose production (HGP) was more suppressed (-1.56 +/- 0.07 v -0.63 +/- 0.34 mg/kg/min, P < .05, 220 to 270 minutes). Oxidative glucose disposal (indirect calorimetry) was enhanced (3.09 +/- 0.24 v 2.70 +/- 0.37 mg/kg/min, P = .08), whereas glucose storage, as well as the fractional velocity for glycogen synthase activity, were unaltered during octreotide administration. Conversely, octreotide decreased lipid oxidation (0.12 +/- 0.1 v 0.41 +/- 0.15 mg/kg/min, P < .05). In conclusion, a low-dose octrotide infusion for 4 days to IDDM subjects leads to significantly increased insulin sensitivity.

The effect of a continuous infusion of a somatostatin analogue (octreotide) for two years on growth hormone secretion and height prediction in tall children

OBJECTIVE

Strategies to limit the final height of tall children have centred on the use of high doses of sex steroids to advance skeletal maturation. This limits therapy to the peripubertal years whereas the greatest gain in height is in the prepubertal years. Prepubertal growth is largely GH dependent and previous work has documented modulation of GH secretion by once or twice daily subcutaneous injection of the somatostatin analogue octreotide. In this study we have determined the effects of a nocturnal infusion of octreotide on height prediction, GH and TSH secretion in tall children.

DESIGN

A patient controlled study in which height prediction and 24-hour GH and TSH secretion were compared prior to and during the course of a 2-year treatment programme with a nocturnal infusion of octreotide in a dose of 1-1.5 micrograms/kg body weight given subcutaneously.

PATIENTS

Nine tall children (4M; 5F) aged 7-14 years with final height predictions of 179 cm or greater in the girls and between 183 and 202 cm in the boys were studied.

MEASUREMENTS

Height prediction using the Tanner-Whitehouse system prior to and at the end of 2 years of treatment. Twenty-four-hour serum GH and TSH concentration profiles, thyroxine, IGF-I and GH responses to GHRH(1-29)NH2 were studied prior to and at the end of the first year of therapy.

RESULTS

Treatment with octreotide led to a significant reduction in height prediction in 7 of the 8 children who completed treatment (median reduction 3.5 cm, range +2.8 to -11.5; Wilcoxon, P = 0.05). Twenty-four-hour mean serum GH concentration decreased by 50% (MANOVA, P = 0.03) during therapy and this was accompanied by an increase in the percentage of samples giving values less than 0.5 mU/l (MANOVA, P = 0.02). There was no overall change in the serum GH response to GHRH(1-29)NH2 or serum IGF-I concentrations. Nocturnal serum TSH concentrations were reduced to levels observed during the daytime but these changes had no effect on serum thyroxine values. One patient developed gallstones during the course of therapy.

CONCLUSIONS

A nocturnal infusion of octreotide reduces GH secretion and height prediction in tall children. Therapy with somatostatin analogues allows a reduction in growth rate to be instigated in the prepubertal years reducing the actual height from which will commence the pubertal growth spurt.

Continuous versus intermittent subcutaneous infusion of octreotide in the treatment of acromegaly

This review evaluates the efficacy, tolerability, and safety of continuous subcutaneous infusion (CSI) relative to intermittent subcutaneous injection (ISI) of the somatostatin analog, octreotide in the treatment of acromegaly. Data was extracted from five clinical series using CSI octreotide in acromegaly, six reports comparing CSI to ISI, and three studies comparing pulsatile subcutaneous infusion (PSI) to ISI. Effects of each drug regimen on the control of growth hormone (GH), insulin-like growth factor (IGF-1), clinical symptomatology, pituitary tumor size, and adverse effects were evaluated. Normalization of serum GH or IGF-1 levels, as well as improvement in clinical symptoms was reported in the majority of the patients studied. Cases in which pituitary adenomas decreased in size were also documented during the study period. When the effects of CSI were compared with ISI, a more pronounced control of GH and IGF-1 was observed. In addition, diurnal GH fluctuation during CSI was significantly reduced relative to ISI in two reports. Moreover, in two patients, CSI achieved similar clinical and biochemical effects at lower doses than when the drug was given by ISI. Finally, adverse effects with CSI may be less severe than with ISI. Continuous subcutaneous infusion of octreotide produced biochemical improvement in 67 of the 88 patients reviewed. When compared with ISI, CSI induced more pronounced biochemical control, often with less fluctuation in GH and IGF-1 levels. Because of a lack of data, definite conclusions regarding the differences between regimens on clinical symptomatology and tolerability could not be discerned. A large prospective, long-term randomized crossover study is recommended to make these determinations.

Pharmacokinetic and pharmacodynamic properties of a long-acting formulation of the new somatostatin analogue, lanreotide, in normal healthy volunteers

1. The aims of the study were to assess the pharmacokinetic parameters and the hormonal effects of the slow-release formulation of the somatostatin analogue (SR-L) in normal male volunteers. 2. Eight healthy males were studied. For the determination of basal values blood was sampled before the injection of vehicle and then every other hour for 8 h in order to measure plasma GH, prolactin (PRL), TSH, free thyroxin (fT4), insulin and glucagon levels. Plasma insulin-like growth factor 1 (IGF-1) levels were measured on a single sample. On day 1 of the study, 30 mg SR-L was administered intramuscularly. Blood was drawn just before injection and then every other hour for a period of 8 h. Thereafter, blood was sampled three times a week for 3 weeks in order to measure lanreotide, IGF-1, TSH, fT4 and PRL concentrations. Plasma GH was determined on days 6 and 11 of the study. 3. Plasma lanreotide concentrations rose to 38.3 +/- 4.1 ng ml-1 2 h following injection. The levels then progressively decreased, remaining above 1.5 ng ml-1 until day 11 and reaching 0.92 +/- 0.28 ng ml-1 2 weeks after injection. The apparent plasma half-life and mean residence time were 4.52 +/- 0.50 and 5.48 +/- 0.51 days respectively. 4. By comparison with the control day, plasma insulin concentrations only decreased 2 h following injection, whereas plasma glucagon did not change at any time. 5. Plasma TSH concentrations were significantly (P < 0.01) reduced from 2 h to day 4 following SR-L injection.2+ '

Effects of a slow-release formulation of the new somatostatin analogue lanreotide in TSH-secreting pituitary adenomas

OBJECTIVE

Somatostatin analogues have been proposed for the treatment of thyrotrophinomas. However, this treatment requires several s.c. injections a day to be effective. The present study had the following aims: (i) appraisal of the efficacy of a single dose of two somatostatin analogues (lanreotide and octreotide) to acutely inhibit TSH secretion of TSH-secreting pituitary adenomas; (ii) assessment of the efficacy of a single injection of a slow release formulation of lanreotide (SR-L) in reducing TSH and thyroid hormone secretions in the same cases; and (iii) evaluation of the effects of SR-L used for 3-6 months on hormone secretion and tumour size.

PATIENTS

Four patients with hyperthyroidism linked to a TSH-secreting pituitary adenoma found on pituitary magnetic resonance imaging (MRI) and subsequently proved by immunohistochemistry were studied.

METHODS

In the first step of the study the patients received in a random order, vehicle, 150 micrograms octreotide and 500 micrograms lanreotide as a single s.c. injection. Measurements of plasma TSH, free T4 (fT4), free T3 (fT3) and free alpha subunit (fAS) levels were carried out before injection and then every other hour for 8 hours. In the second part of the study, after a basal blood sample (0800 h), each patient received 30 mg lanreotide as an i.m. injection of SR-L. Blood was sampled 2 hours later and then three times a week for 3 weeks in order to measure plasma TSH, fT4, fT3 and lanreotide levels using radioimmunoassays. The patients then received one SR-L injection twice or in one case three times a month for 3-6 months. Plasma TSH, fT4 and fT3 levels were measured monthly and a pituitary MRI was performed at the end of the treatment with SR-L.

RESULTS

500 micrograms lanreotide acutely reduced plasma TSH and fAS levels to the same extent as 150 micrograms octreotide. Two hours after a single i.m. injection of SR-L plasma lanreotide levels reached 7.8 +/- 0.6 micrograms/l and then progressively decreased, being 1.8 +/- 0.2 microgram/l on day 2 and 1.1 +/- 0.3 microgram/l on day 14 after the injection. Plasma TSH level decreased from basal value (mean +/- SEM 4.4 +/- 1.2 mlU/l) within 2 hours (2.5 +/- 0.8 mlU/l) and further declined to 0.8 +/- 0.2 ml/Ul on day 2 following the injection. Depending on the patient, plasma TSH levels were reduced for a period of 6-15 days. Plasma fT4, fT3 levels were normalized on day 2 and remained in the normal range for a period of time of 9-20 days. During long-term treatment, abdominal cramps and diarrhoea appeared, leading to interruption of the treatment in one patient. The treatment was well tolerated in the other three patients. Plasma TSH and thyroid hormone levels progressively decreased during the treatment. No change in adenoma volume was observed after 3-6 months of therapy.

CONCLUSIONS

This study shows that (i) lanreotide is able to inhibit acutely TSH secretion in thyrotrophinomas and that a single s.c. injection of 500 micrograms lanreotide is as effective as 150 micrograms octreotide; (ii) SR-L appears to be able to reduce plasma TSH and to normalize fT4 and fT3 levels for 9-20 days in patients with thyrotrophinomas; (iii) this effect is maintained throughout the treatment using two or three SR-L injections monthly for months. These results suggest that SR-L could be used as a treatment of thyrotrophinomas and avoids the drawbacks of the modes of administration of other somatostatin analogues used in such cases.

Postprandial gall bladder motility and hormone release during intermittent and continuous subcutaneous octreotide treatment in acromegaly

Repeated daily injections of the somatostatin analogue, octreotide (SMS201-995, Sandostatin) are an effective treatment for acromegaly, but lead to gall stone formation in about 50% of cases during longterm treatment. This is probably because of impaired gall bladder contraction. This study examined whether the timing of intermittent injections in relation to meals, or alternatively, continuous 24 hour subcutaneous octreotide infusion (CSOI) might avert adverse effects on gall bladder contraction. In six patients with active acromegaly, gall bladder volume, plasma cholecystokinin (CCK), and pancreatic polypeptide (PP) were measured in the fasting state and after consumption of a fatty meal. Measurements were made on five separate days: (a) without treatment, (b) 45 minutes after 100 micrograms octreotide given subcutaneously, (c) four hours after 100 micrograms octreotide given subcutaneously, (d) eight hours after 100 micrograms octreotide given subcutaneously, and (e) during CSOI of 300 micrograms/24 h for two weeks. Without treatment, postprandial gall bladder contraction was 86.2 (2.1%). Fasting gall bladder volume increased after octreotide injection and was almost doubled during CSOI. Octreotide injections impaired postprandial gall bladder contraction as well as CCK and PP release for at least four hours. Eight hours after injection and during CSOI, postprandial gall bladder contraction was partly restored (43.4% and 50.8% respectively). Postprandial CCK release was normal at eight hours after injection but very low during CSOI. PP release was suppressed by each mode of octreotide treatment. This study indicates that octreotide injections impair postprandial gall bladder contraction for at least four hours. Eight hours after injection and during CSOI, gall bladder contraction is partly restored.

Serum immunoreactive and bioactive lactogenic hormones in advanced breast cancer patients treated with bromocriptine and octreotide

6 patients with advanced breast cancer who had failed first and second line endocrine therapies received bromocriptine (1.25-2.5 mg twice daily per os) and octreotide (Sandostatin) via a continuous subcutaneous infusion (200-400 micrograms/24 h) until disease progression. Pre-treatment 24-h profiles of serum lactogenic hormones and their response to standard provocative tests were established and repeated at 2 weeks, and 3 and 6 months (or at tumour progression). Immunoreactive prolactin (ir-PRL), growth hormone (ir-GH) and insulin-like growth factor I (IGF-I) were measured by radioimmunoassay and bioactive lactogenic hormone levels (BLH) were estimated using the Nb2 rat lymphoma cell bioassay. Before treatment all patients showed episodic secretion of ir-PRL, ir-GH and BLH and provocative stimuli resulted in a peak of ir-GH and BLH maximal between 60 and 90 min after injection but no change in ir-PRL. After 2 weeks of treatment, ir-PRL levels were reduced to below the limit of detection in all 6 patients. Peaks of ir-GH and BLH were still apparent, although much reduced. Immunoreactive PRL continued to be profoundly suppressed in 3 of the 4 patients who remained on treatment for 3 to 6 months. Small pulses of ir-GH were still detectable in these patients with which BLH was, again, well correlated. After 2 weeks of treatment, serum IGF-I levels were reduced by 9-54% of the pretreatment values and generally remained suppressed throughout treatment. Clinically, 4 patients did not show disease progression for periods of up to 6 months and side-effects were minimal.

The pulsatile GH secretion in acromegaly: hypothalamic or pituitary origin?

OBJECTIVE

We studied the effects of different modes of octreotide therapy on the pulsatile pattern of GH release in an attempt to define better its regulation by growth hormone-releasing hormone (GHRH) and somatostatin and its effects on IGF-I plasma levels in acromegaly.

DESIGN

In six acromegalic patients not cured by previous treatment we compared the 24-hour GH secretion profiles under basal conditions with subcutaneous (s.c.) bolus injections of 100 micrograms octreotide every 8 hours and with continuous s.c. infusions of the same daily dose. Blood samples were taken every 10 minutes over 24 hours followed by a GHRH test (100 micrograms GHRH i.v.) with blood sampling every 15 minutes for another 2 hours. After a 4-week interval all patients were treated either by the bolus or continuous mode of octreotide application in a randomized cross-over design. On day 4 of treatment blood sampling and GHRH test were repeated. Octreotide treatment was withdrawn for another 4 weeks; all patients then received the alternate application mode and were measured under similar conditions.

MEASUREMENTS

Serum GH and plasma IGF-I concentrations were analysed by serial array averaging. IGF-I levels were measured in two different assays with and without previous protein extraction. For GH pulse detection three different algorithms (Cluster, Pulsar, Desade) were applied.

RESULTS

With both treatments, the initially elevated basal 24-hour mean serum GH concentrations (58.0 +/- 9.7 mU/l mean +/- SEM) decreased significantly (bolus: 11.5 +/- 4.9 mU/l, P < 0.001 vs basal; continuous infusion: 7.6 +/- 1.9 mU/l, P < 0.001 vs basal) after 4 days. GH suppression was significantly more pronounced following continuous infusion than bolus (P < 0.05). IGF-I plasma concentrations were lowered significantly (P < 0.05) with both forms of treatment which did not differ between themselves. Bolus and continuous infusion treatment significantly inhibited (P < 0.05) the amplitudes of pulsatile GH release, but did not change the pulse frequency. In two of the patients, GHRH stimulation did not increase GH serum levels suggesting a constitutive activation of adenylyl cyclase.

CONCLUSION

Continuous subcutaneous octreotide treatment in acromegaly suppresses mean GH levels better than bolus injection. The number of GH pulses remains unaffected by both modes of treatment providing evidence against a somatostatinergic mechanism of pulsatile GH secretion in these patients. The unchanged frequency of pulsatile GH release in the patients unresponsive to exogenous GHRH indicates that this pattern might be independent of hypothalamic GHRH and somatostatin and suggests a pituitary-derived mechanism for GH pulse generation in acromegaly.

Long-term efficacy and tolerability of octreotide treatment in acromegaly

Twenty-five acromegalic patients were studied during 6 years of treatment with octreotide, with a particular focus on the following parameters: (1) Administration schedule: in 10 patients, continuous subcutaneous (SC) octreotide infusion was compared with injections of octreotide at three dose levels (100, 250, and 1,500 micrograms/24 h) and was found to induce a greater and less-fluctuating 24-hour growth hormone (GH) suppression. (2) Carbohydrate tolerance: average 24-hour blood glucose levels were unaffected by octreotide, regardless of administration schedule. Oral carbohydrate tolerance and intravenous (IV) glucose tolerance were unaffected by continuous octreotide infusion. However, octreotide injection given shortly before the tests reduced carbohydrate tolerance. (3) Thyroid function: octreotide and somatostatin acutely reduce the response of thyroid-stimulating hormone (TSH) to thyrotropin-releasing hormone (TRH). After a few days of treatment, it was demonstrated that octreotide slightly inhibits iodothyronine deiodination and induces a transient reduction in serum triiodothyronine (T3), rapidly compensated for by a persistent slight elevation of serum TSH. (4) Fat absorption was estimated as 24-hour fecal fat content and found to be in the same high-normal range before and after octreotide treatment. Vitamin K and D absorption were unaffected by octreotide. The incidence of gallstone formation was not greater than in the general Danish population, possibly due to the schedule used for octreotide injections. (5) Foot volume was regularly estimated and found to decrease with time, on average by 12% during the first 18 months.(ABSTRACT TRUNCATED AT 250 WORDS)

From somatostatin to sandostatin: pharmacodynamics and pharmacokinetics

Somatostatin (SRIF) and its octapeptide analogue, octreotide (Sandostatin), have a similar high affinity for specific receptors with 50% inhibitory concentrations (IC50s) in the subnanomolar range. Hence, the striking superiority of octreotide in vivo, which includes duration of action, specificity, and potency, must originate from its different distribution, metabolism, and excretion behavior. In animals and humans, investigations of their pharmacodynamic/pharmacokinetic relationship show plasma levels of 0.2 to 0.5 ng/mL (approximately 0.3 nmol/L) to be therapeutically relevant for both peptides. The much lower clearance rates and improved metabolic stability in the circulation and in target organs of octreotide, compared with SRIF, result in much longer-lasting, therapeutically relevant plasma and tissue levels and therefore in a longer duration of action. Their apparently specific inhibitory action on growth hormone when compared with that on insulin is pharmacodynamically based, and may be exaggerated by physiological mechanisms of carbohydrate regulation. In summary, there is a distinct relationship between the pharmacokinetic profiles and pharmacodynamic behavior of SRIF and its analogue. Sandostatin.

Preliminary results with Sandostatin nasal powder in acromegalic patients

This report details the first half of a double-blind, crossover sequence (Latin square) study of local and hormonal effects of nasally insufflated Sandostatin compared with those of subcutaneously injected Sandostatin. Nine of the planned 16 patients have been studied. They received a single application of 0.5, 1.0, and 2.0 mg Sandostatin as nasal powder and 0.1 mg by subcutaneous (SC) injection. The results indicate that absorption from the nasal epithelium occurs after approximately 10 minutes and comprises approximately 20% of the dose administered. This indicates that peak serum Sandostatin values occur very rapidly, ie, 10 minutes after application. After approximately 2 hours, the serum disappearance rates are similar to those obtained after SC injection. The suppressive effect on serum growth hormone (GH) levels is equal with the two forms of application and suggests that future clinical treatment with an intranasal application of 0.5 mg thrice daily is feasible. No side effects were noted apart from an immediate swelling of nasal mucosa, which receded gradually over the following 2 hours. This was either unnoticed or considered insignificant by the patients and will probably be deemed harmless by the rhinologist in eventual long-term clinical trials.

The role of Sandostatin in acromegaly

Long-acting somatostatin analogues are extensively used for the treatment of acromegalic patients who have not been cured by surgery or for whom surgery is contraindicated or hazardous. Such an analogue, Sandostatin, has been approved for this indication in various countries and to date an overall review is feasible. From the literature and our experience, clinical response of acromegaly is attained in 60% to 70%, with mainly a reduction in headaches, arthralgias, and acral growth. Hormonal response, evaluated on plasma growth hormone (GH) levels, is observed in more than 80% of the patients. In 36% to 45% of the patients, plasma GH levels are reduced to near-normal values, and in 50% of the patients, the percentage of reduction is greater than 50% of pretreatment values. The major source of concern is the occurrence of gallstones during the treatment; its frequency is evaluated differently. From the largest well-documented series, we retain a percentage of 12.5% of newly occurring cholelithiasis and in most cases they remain asymptomatic. Tumor shrinkage is minor in most cases.

Presurgical octreotide treatment in acromegaly

The aim of this study was to determine the role of octreotide administration in acromegalic patients as a preparation for selective adenomectomy using transsphenoidal route. Octreotide was administered for 3 to 6 weeks before surgery in 12 patients and for 4 to 39 months in 25 patients. The clinical response was judged as excellent or good in 10 of 12 patients from group I and in 23 of 25 patients from group II. Marked reduction (ie, greater than 50% of initial values) in serum growth hormone (GH) levels was seen in all patients, with levels to less than 5 micrograms/L in 68% of patients and less than 2 micrograms/L in 27%. Insulin-like growth factor 1 (IGF-1) levels decreased to within normal limits in half the cases. During long-term treatment, an escape phenomenon could be seen. Varying degrees of tumor shrinkage were seen in more than 50% of cases. During surgery, with regard to the relative ease or difficulty in removing the tumor, the consistency of the tumor and the separation of normal from pathological tissue, no significant difference was observed between patients given octreotide and those from control series. Morphological changes in adenomatous tissue were rather small. The surgical outcome was similar in the pretreated series as in the control series, except in enclosed adenomas, which showed a tendency to a higher success rate. Since octreotide improves both the clinical condition and hormonal parameters and induces varying degrees of tumor shrinkage, it is potentially useful as an adjunct to surgery. Morphological data suggest that octreotide exercises a functional inhibitory effect on GH release.

A comparison of octreotide delivered by continuous subcutaneous infusion with intermittent injection in the treatment of acromegaly

This study was undertaken to evaluate GH, IGF1 and drug levels during incremental continuous subcutaneous infusion of octreotide and compare these parameters following long-term treatment of 300 micrograms 24 h-1 by intermittent injection in a group of acromegalic patients. Ten patients were treated by continuous subcutaneous infusion in increasing dose from 200 micrograms 24 h-1 to 1600 micrograms 24 h-1; this resulted in consistent 24-h growth hormone suppression (less than 5.0 mU l-1), and normalisation of IGF1; the optimum dose was 400 micrograms 24 h-1, the maximum dose was tolerated without any untoward effects. There was no deterioration in carbohydrate tolerance despite a marked decrease in fasting and stimulated insulin levels. After 1 year of maintenance treatment, 300 micrograms 24 h-1 by intermittent injection, patients were re-evaluated; GH levels were not so consistently suppressed over the 24-h period and carbohydrate tolerance had deteriorated. A sub-group of patients with sub-optimal GH suppression on this regimen were identified and reassessed after 6 weeks treatment with an increased dose, 600 micrograms 24 h-1 by intermittent injection; both mean GH suppression and carbohydrate tolerance improved. The dose of drug and method of administration is best adjusted for each patient to achieve optimum GH suppression, thereby minimise compensatory hyperinsuliaemia and hopefully reduce morbidity and mortality. Alterations in pituitary tumour size and acquisition of gallstones during treatment have been observed which substantiate the need to re-evaluate these parameters on routine follow-up of acromegalic patients on long-term octreotide.

Effects of antibodies against octreotide in two patients with acromegaly

Two patients developed specific IgG antibodies against octreotide after 2-3 years' treatment for acromegaly with this long acting somatostatin analogue. The presence of these antibodies reduced the plasma disappearance rate of total extractable octreotide by 60 and 80% respectively. When compared to that of non-immune acromegalic patients, the plasma half-life of octreotide in these two patients was 300 and 450 vs 110 min in those with no detectable octreotide antibodies. The sole observed consequence of the immunization was a marked prolongation of the interval of maximum GH inhibition from a mean of 5 to 8 and 10 h in the two patients described after octreotide injection.

The use of continuous subcutaneous octreotide infusion in brittle type 1 diabetic patients

Two Type 1 diabetic patients with brittle diabetes were successfully treated using continuous SC octreotide (Sandostatin) infusion (200 micrograms 24-h-1) for 6 months and 12 months. When the analogue was discontinued, rapid deterioration in glucose control and ketonuria recurred in one patient and diabetic ketoacidosis in the other. These were corrected after reinstitution of the analogue.

Reduction in sella turcica volume. An effect of long-term treatment with the somatostatin analogue, SMS 201-995, in acromegalic patients

Ten patients with acromegaly were treated with the long-acting somatostatin analogue, Sandostatin (SMS 201-995, octreotide) for more than one year. Computerized tomography was performed before and on 4 different occasions during the treatment. Sella turcica volumes were calculated in nine patients and showed a gradual decrease in all, averaging 32% +/- 14.6%, P less than 0.001 at the end of the study, which is probably indicative of a simultaneous reduction in adenoma size.

Acute effects of a somatostatin analogue on kidney function in type 1 diabetic patients

Suppression of growth hormone by means of somatostatin has been suggested as a possible adjunct therapy in Type 1 diabetes. To assess the acute effect of the somatostatin analogue SMS 201-995 on kidney function in uncomplicated Type 1 diabetes, 13 normoalbuminuric, normotensive diabetic patients were investigated before and during IV infusion of SMS 201-995 (8 micrograms h-1). A control experiment with infusion of carrier only was also performed. The SMS infusion induced a reduction in the glomerular filtration rate (clearance of 125I-iothalamate) and renal plasma flow (131I-hippuran) from 140 +/- 15 (mean +/- SD) and 550 +/- 69 to 131 +/- 14 (2p less than 0.005) and 492 +/- 73 ml min-1 1.73-m-2 (2p less than 0.001), while filtration fraction and total renal resistance rose (both 2p less than 0.001). Urinary albumin excretion rate, blood pressure, and blood glucose concentration were unchanged. Plasma growth hormone and glucagon were significantly suppressed. The reduction in glomerular filtration rate and renal plasma flow correlated with the fall in glucagon concentration (r = 0.57, 2p = 0.04, and r = 0.63, 2p = 0.02). The urinary flow rate was markedly reduced, urine osmolality increased, and fractional excretion of sodium, calcium, and phosphate were reduced. Arginine vasopressin, atrial natriuretic peptide, angiotensin II, and aldosterone were unchanged by the SMS infusion. Thus SMS 201-995 acutely reduces glomerular filtration rate and renal plasma flow in uncomplicated Type 1 diabetes and has an antidiuretic effect. The effects may be related to suppression of glucagon secretion.

A preliminary report on the role of somatostatin analogue (SMS 201-995) in the management of children with tall stature

We have studied the effect of somatostatin analogue (SMS 201-995) given as a subcutaneous injection on the growth and growth hormone secretion in seven tall children (two male; five female). SMS 201-995 was given in doses of 37.5 or 50 micrograms on a once or twice-daily regimen. Growth velocity decreased from a pretreatment median of 8.3 cm/year (range 5.5-12.2) to 3.0 cm/year (range 0.2-4.5) after 6 months treatment (Wilcoxon, P = 0.02). In three of the children therapy was discontinued for the next 6 months with restoration of growth rate to pretreatment values in two of the three. Growth hormone secretion decreased as a result of SMS 201-995 therapy although one child needed a twice-daily regimen to achieve long-term suppression. Final height measurements were reduced in four of five patients with an overall reduction between 1.1 and 6.3 cm and no change in the other. No effects of treatment on fasting glucose and insulin, glycosylated haemoglobin or serum thyroxine concentrations were observed. These preliminary studies suggest that SMS 201-995 may have a role in the management of the growth of tall children but the optimum mode of administration remains to be established.

Continuous infusion of octreotide in acromegaly

15 patients with acromegaly were treated with continuous subcutaneous infusion of octreotide in increasing dose from 200 to 1600 micrograms per 24 h by 200 micrograms increments each week. Patients were studied during the initial 7 h of infusion, weekly at each dose level, then after 1 and 2 months at maximum dosage. 13 patients responded well, as judged by growth hormone (GH) suppression and return of insulin-like growth factor 1 to normal, although 1 patient withdrew due to adverse effects; 2 patients showed no significant reduction in GH. In the 12 responders GH level fell within the first 3 h of infusion at a mean plasma octreotide level of 0.76 (SE 0.26) micrograms/l, corresponding to 25 micrograms of infused drug. Optimum suppression of GH occurred at a dosage of 600 micrograms per 24 h, a plasma drug level of 3.5 (0.5) micrograms/l. A definite reduction in tumour size was seen on computerised tomographic scan in 2 patients. All responders noted subjective improvement in acromegalic symptoms. Adverse effects comprised gastrointestinal disturbances, which were transient and mild in 14 patients but severe in 1; biliary sludging occurred in 1 patient. No significant deterioration in carbohydrate tolerance was seen in the responders.

The cardiovascular effects of octreotide treatment in acromegaly: an echocardiographic study

Nine acromegalic patients were treated by the somatostatin analogue SMS 201-995 octreotide (Sandostatin (octreotide), Sandoz, Basle, Switzerland] 250 micrograms/day in 4 divided s.c. injections (50 + 50 + 50 + 100 micrograms) for 1 month, 250 micrograms/24 has continuous s.c. infusions for another month and thereafter 200 micrograms three times daily as s.c. injections. Echocardiography was performed before the treatment, following 1 month of octreotide s.c. infusion/injection and after 6 and 12 months of octreotide treatment. No differences in serum growth hormone, heart rate, blood pressure, cardiac contractility or left ventricular wall mass or wall thickness were found between the infusion and the injection periods. As compared to the pretreatment levels serum growth hormone decreased by 62 and 66% respectively following 6 and 12 months octreotide treatment. The heart rate per minute (+/- SD) decreased from the pretreatment level of 75 +/- 12 to 63 +/- 13 (P less than 0.007) at month 12. The systolic and the diastolic blood pressure decreased from the pretreatment level of 121 +/- 8 and 79 +/- 5 mmHg respectively to 108 +/- 7 (P less than 0.0007) and 71 +/- 7 mmHg (P less than 0.0001) respectively at month 12.(ABSTRACT TRUNCATED AT 250 WORDS)

Somatostatin analogue administration prevents increase in kidney somatomedin C and initial renal growth in diabetic and uninephrectomized rats

In a previous study we demonstrated that the kidney content of somatomedin C was maximal one to two days after uninephrectomy or induction of diabetes, and that insulin treatment prevented an increase in kidney somatomedin C as well as kidney growth in diabetic animals. In the present study we have examined the effect of a somatostatin analogue on kidney somatomedin C and initial renal growth in the two experimental situations. The kidney hypertrophy in untreated diabetic animals amounted to 23% four days after streptozotocin injection and followed an increase in kidney somatomedin C content of 60% reaching the maximum after 48 h. In young and old uninephrectomized rats kidney growth was 19% and 16% after four days. In young animals a prompt increase of 50% in kidney somatomedin C was seen as reaching the maximum after 24 h, while the somatomedin C content in kidneys from old animals was maximal after 48 h (increase of 58%) in good accordance with the slightly slower kidney growth. The new findings of the present study are that administration of a long-acting somatostatin analogue (Sandostatin) effectively prevented the obligatory increase in kidney somatomedin C content as well as kidney growth both in experimental diabetes and after uninephrectomy. It is noteworthy that Sandostatin administration did not alter the metabolic state in diabetic animals indicating that the inhibition of kidney hypertrophy could not be attributed to improved metabolic control. The results thus support the concept that somatomedin C is involved in initial diabetic and post-nephrectomy renal growth.

Effect of a new long-acting somatostatin analogue (SMS 201-995) on glycemic and hormonal profiles in insulin-treated type II diabetic patients

Five type II diabetic patients were studied after secondary failure of oral agents, with and without the addition of the new long-acting somatostatin analogue SMS 201-995 to an intermediate-acting insulin regimen. SMS 201-995 was administered twice daily, before breakfast and dinner, as 100 micrograms sc injections, and resulted in a lowering of plasma glucose, as well as of plasma glucagon and serum C-peptide levels. SMS 201-995 abolished postprandial glycemic and xylosemic peaks related to meals and to oral d-xylose when they were taken shortly after the administration of the analogue, while it had no effect on glycemic and xylosemic increments that followed the midday meal. The new somatostatin analogue improves glucose tolerance in type II diabetic patients, both by inhibiting counterregulatory hormones and by delaying and reducing intestinal absorption of nutrients. Its administration could lead to a reduction of daily insulin requirements. Our findings indicate that SMS 201-995 may have a role as an adjunct to insulin in the management of type II diabetic patients after secondary failure of oral agents.