Clinical and biochemical effects of incremental doses of the long-acting somatostatin analogue SMS 201-995 in ten acromegalic patients

Treatment of Chinese acromegaly with a combination of bromocriptine and octreotide

BACKGROUND

Good results have been reported with combined use of octreotide and bromocriptine in acromegalic Caucasians. Data concerning the efficacy and tolerability of this combination treatment in Chinese acromegalic patients are scanty.

AIM

The aim of this study was to assess the efficacy and tolerability of combined therapy using bromocriptine and octreotide in the treatment of acromegaly in Chinese patients and to compare the cost-effectiveness of various regimes.

METHODS

Sixteen Chinese acromegalic patients with growth hormone (GH) concentration not suppressible to below 5 mU/L (2 microg/L) during an extended OGTT were recruited to undergo four phases of the study. During the study period, the patients were given bromocriptine alone, bromocriptine and low dose octreotide, bromocriptine and medium dose octreotide, and medium dose octreotide alone. Plasma concentrations of GH and insulin-like growth factor-1 (IGF-1) were measured before and after the completion of each phase.

RESULTS

The number of patients reaching target GH concentrations was significantly higher when treated with octreotide compared to baseline (p<0.05). Bromocriptine alone had a significant effect but not to the extent of octreotide alone. A combination of low dose octreotide and bromocriptine is as efficacious in the treatment of acromegaly as high dose octreotide. None of the patients suffered from serious adverse effects.

CONCLUSION

The results confirmed the usefulness and tolerability of bromocriptine and octreotide in Chinese acromegalics. The most cost-effective regime in this study was a combination of low dose octreotide and bromocriptine.

Clinical features and growth fractions of pituitary adenomas

BACKGROUND

The Ki-67 monoclonal antibody is expressed by proliferating and dividing cells, but not by resting cells. The specificity of the monoclonal antibody, MIB-1, against the Ki-67 antigen has been established by immunostaining of formalin-fixed paraffin-embedded tissue in a microwave oven.

METHODS

The growth fraction of 85 pituitary adenomas was studied retrospectively by immunohistochemical analysis using the monoclonal antibody MIB-1. The adenomas were classified into three types: microadenoma, expansive type, and invasive type, based on findings on Gd DTPA enhanced magnetic resonance imaging.

RESULTS

The mean MIB-1 index in nonfunctioning microadenomas was higher than in expansive and invasive adenomas, but this difference was not significant. The MIB-1 index in younger patients (under 30 years) with nonfunctioning adenomas was significantly higher than in patients over 40 years of age. One of 14 patients with recurrent disease had an elevated MIB-1 index, but generally patients with an MIB-1 index over 2.0% did not suffer recurrence. The mean MIB-1 index was higher in expansive and invasive functioning adenomas than microadenomas, but not significantly. No correlation between the MIB-1 index and the serum GH or PRL concentration was established. No MIB-1 positive nuclei were observed in two GH-producing adenomas treated with the somatostatin analog SMS 201-995.

CONCLUSIONS

No significant relationship was identified between growth fraction and the invasiveness or recurrence of pituitary adenomas. The growth fraction of nonfunctioning pituitary adenomas was higher in patients under 30 years than over 40 years of age.

An audit of long-term octreotide therapy for acromegaly

BACKGROUND

Octreotide has been successfully used for the treatment of acromegaly, but little long-term data are available.

AIMS

To determine the long-term efficacy and safety of octreotide in the treatment of acromegaly.

METHODS

Twenty-seven patients with acromegaly were treated with octreotide in a non randomised study. Six patients had not had previous surgery or radiotherapy, and were treated with octreotide alone. Symptoms of acromegaly, IGF-I levels, growth hormone suppression by glucose, pituitary tumour size, and side effects were monitored. The median duration of treatment was 44 months (range six-102).

RESULTS

Symptom control was excellent. Twenty (74%) patients had a reduction of IGF-I into the normal range. IGF-I levels fell after one year from 94.2 +/- 6.1 nmol/L (mean +/- SEM) to 50.0 +/- 2.7 nmol/L (p < 0.0001). Ten of 13 (77%) patients had normal IGF-I levels after four years. These reductions have persisted for up to nine years of octreotide therapy. The GH response to glucose was normalised in 14 of 16 (88%) subjects. Eleven of 25 (44%) patients had a reduction in pituitary gland height. Side effects were common, but usually of a minor nature. Cholelithiasis occurred in 39% of patients. Two patients ceased octreotide because of side effects.

CONCLUSIONS

We conclude that octreotide is an effective and safe long-term treatment for acromegaly. It is a useful adjunct to surgery, and may be offered as sole therapy for patients with smaller adenomas.

Clinical features and differential diagnosis of pituitary tumours with emphasis on acromegaly

Pituitary adenomas are frequently encountered, benign intracranial tumours. Clinically classified according to their capacity to produce and secrete hormones, pituitary tumours are diagnosed from the clinical manifestations and biochemical findings of specific pituitary hormone overproduction or of impaired pituitary function due to pressure on normal pituitary cells, the pituitary stalk or the hypothalamus. Additionally, the tumour may result in neurological manifestations due to its effect as an intracranial space-occupying lesion. Pituitary adenomas may present acutely with pituitary apoplexy after intrapituitary haemorrhage or infarction. The subsequent hypofunction of the pituitary with concomitant neurological sequelae of an expanding intracranial mass are often associated with excruciating headache, diplopia and visual field defects. Gradually developing neurological deficits or secondary endocrine failure over several years may precede the recognition of non-secretory tumours (30-40% of pituitary adenomas) as well as some of the hormone-producing adenomas, especially when they expand beyond the confines of the sella turcica. Asymptomatic masses occur in the pituitary in 5-27% of unselected autopsy series. About 10-20% of pituitaries imaged as part of a brain study contain lesions 'consistent with a pituitary adenoma', with about half being pituitary adenomas ('incidentalomas'). Many advocate screening such cases for a wide spectrum of pituitary function abnormalities. Clinical judgement should be utilized to determine the extent of the work-up and the frequency of follow-up. Acromegaly, a clinical syndrome caused by excess growth hormone secretion, accounts for one-sixth of resected pituitary tumours. This disorder leads to chronic progressive disability and a shortened life span, with approximately 50% of untreated acromegalic patients experiencing premature death. The prevalence of acromegaly has been estimated to range from 50 to 70 per million, with the age of diagnosis usually between the third and fifth decades. Conditions associated with acromegaly include glucose intolerance, diabetes mellitus, lipid abnormalities, cholelithiasis, goitre, and hyperthyroidism, respiratory complications, hypertension, cardiovascular disease, and calcium metabolism abnormalities. An association between acromegaly and cancer, especially of the colon, is now recognized. Epidemiological series have indicated that cancer of the colon, breast and other types of malignancy are a cause of death with increased frequency in acromegalics compared with expected rates. Hypopituitary symptoms secondary to the mass effect of macroadenomas in acromegalic patients are common. Among premenopausal women, menstrual irregularities and galactorrhoea have been reported in 40-70%, while more than half of the men complain of impotence and decreased libido.(ABSTRACT TRUNCATED AT 400 WORDS)

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.

Treatment of invasive growth hormone pituitary adenomas with long-acting somatostatin analog SMS 201-995 before transsphenoidal surgery

The purpose of this study was to determine whether the long-acting somatostatin analog SMS 201-995 (octreotide) shrinks growth hormone (GH)-secreting adenomas and improves the results of subsequent transsphenoidal surgery. Ten previously untreated active acromegalic patients (nine women and one man) with invasive tumors were treated with SMS 201-995 (100 micrograms subcutaneously every 8 hours) for 6 weeks prior to transsphenoidal surgery. The clinical activity, mean GH secretion, insulin-like growth factor (IGF)-I concentration, and tumor volume were measured under basal conditions and on Days 14, 28, and 42 of treatment. The SMS 201-995 improved the symptoms of acromegaly in all patients. Mean levels of both GH and IGF-I (+/- standard deviation) were significantly decreased by Day 14 (from 92.9 +/- 30.5 to 44.9 +/- 20.3 micrograms/liter and from 10.6 +/- 7.4 to 5.9 +/- 2.6 U/ml, respectively), after which there were only slight further decreases. Six (60%) of the 10 patients experienced tumor shrinkage ranging from 9% to 78% (mean 30%). When it occurred, tumor shrinkage was significant by Day 14 (7.9 +/- 6.3 to 6.5 +/- 5.1 cu cm) and no further shrinkage was achieved by longer administration. Transsphenoidal surgery reduced postoperative GH levels to less than 2 micrograms/liter and IGF-I to less than 1.5 U/ml in six patients (60%). This percentage of cure is higher than expected from the literature and the authors' previous experience. However, an investigation of the influence of this drug on several parameters, such as reduction of tumor size or GH and IGF-I concentrations, has failed to prove any relationship. Only pretreatment size of the tumor was of predictive value with respect to the surgical outcome.

Cholelithiasis and acromegaly: therapeutic strategies

OBJECTIVE

The aims of this study were (i) to evaluate gall-bladder form and contents, (ii) to assess the prevalence of gallstones in acromegalic patients before octreotide treatment and the incidence of gallstone formation in patients with acromegaly during long-term (6-90 months, mean 44 months) octreotide treatment, and (iii) to test the efficacy of ursodeoxycholic acid in preventing and treating octreotide-induced cholelithiasis.

DESIGN

Forty-nine patients (23 men and 26 women, aged 19-81 years) were studied by repeated gall-bladder ultrasonography performed at baseline and then every 6 months during octreotide therapy. All ultrasound scans were evaluated by the same radiologist. Statistical analysis was performed using the Chi-squared and regression analysis tests.

RESULTS

Asymptomatic stones were recorded in 13/49 patients (26.5%) prior to octreotide treatment (the prevalence of cholelithiasis in the Italian population is 9.5% in men and 18.9% in women). During octreotide therapy gallstones developed in 10/36 patients (27.7%). No significant correlations with sex, age, body mass index, duration of the disease, daily dose and duration of octreotide therapy, altered gall-bladder form, family history of gallbladder stones, basal plasma values of cholesterol and triglycerides were found between the patients (10/36) who developed stones during octreotide treatment and the ones who did not (26/36). Fourteen patients (10 with newly developed stones and four with cholelithiasis diagnosed prior to octreotide) were put on ursodeoxycholic acid at the daily dose of 10 mg/kg. Gallstones completely disappeared in 6/14 patients (42.8%; five patients with newly developed stones and one with stones prior to octreotide therapy) after a mean of 30.8 months of ursodeoxycholic acid treatment. In addition, seven patients were treated with ursodeoxycholic acid at the preventive dose of 450 mg, administered as a once-a-day oral preparation in the evening. However, stones developed in one of these seven patients who was thereafter cured (gallstones completely disappeared) by the therapeutic dose of ursodeoxycholic acid of 10 mg/kg/day after 23 months of treatment.

CONCLUSIONS

This study indicates that (i) acromegaly by itself is correlated with a high prevalence of gallbladder stones, (ii) the long-term treatment with octreotide increases the incidence of cholelithiasis, and (iii) ursodeoxycholic acid is useful in the treatment of gallstones in acromegalic patients but its prophylactic effect in patients on octreotide treatment requires further assessment.

Effect of octreotide on dynamic excretion of bile in Chinese acromegalic patients assessed by [99mTc]EHIDA hepatobiliary scan

We used [99mTc]EHIDA hepatobiliary scintigraphy to determine whether both hepatic bile secretion and gallbladder contractility are suppressed in acromegalic patients receiving long-term treatment with the somatostatin analogue octreotide. We studied three groups of patients: group 1, untreated patients; group 2, average dose of octreotide 500 +/- 100 micrograms/day for 33 +/- 4 months; and group 3, 1000 +/- 200 micrograms/day for 33 +/- 4 months. Images were taken at specified time intervals during the 120-min period following injection of EHIDA. After a single injection of octreotide, group 1 patients demonstrated delayed visualization of the radioisotope in the liver, gallbladder, and duodenum. At the end of long-term treatment, group 2 patients showed a delay in appearance of maximal radioactivity in the gallbladder. Two weeks following discontinuation of octreotide, this parameter had decreased significantly (P < 0.001). In group 3, visualization of the liver, gallbladder, and duodenum were prolonged, with delayed visualization of the gallbladder persisting two weeks after withdrawal (P < 0.005). These results indicate that gallbladder contractility is decreased after a single injection of octreotide and that during chronic octreotide therapy the rate of bile secretion is reduced. Impaired gallbladder contractility normalizes more rapidly after discontinuation of octreotide in patients receiving low doses of the analog.

Gallstones in acromegalic patients undergoing different treatment regimens

The frequency of gallstones during long-term treatment with the somatostatin analogue octreotide reported in different studies varies from 0% to 50%, the reason for this variation being unknown. Therefore, we examined 58 acromegalic patients undergoing different treatment regimens for the frequency of gallstones. Thirteen were treated with octreotide, 20 with bromocriptine, and 25 had no medical treatment after successful neurosurgery. Also, 58 patients without known gallbladder disease served as controls. The postprandial gallbladder contraction was also investigated in 27 acromegalic patients (10 with octreotide, 10 with bromocriptine, and 7 with no medical therapy). Ten of the 58 acromegalic patients were found to have gallstones, 4 of 25 receiving no medical treatment, 4 of 20 treated with dopamine agonists, and 2 of 13 treated with octreotide. In 9 of the 58 control patients, gallstones were detected. Although in the octreotide group the gallstones were newly formed under therapy, there was no difference in gallstone prevalence between the different treatment regimens and the control group. However, the postprandial gallbladder contraction was significantly more often inhibited during octreotide therapy, and this effect was most pronounced during the first hours following injection. Differences in the timing of injections therefore may be an explanation of the variable incidence of cholelithiasis in the different studies.

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.

Gallstones during octreotide therapy

Gallbladder stones (GBS) are found in up to 50% of patients receiving octreotide, but the reported prevalence of cholecystolithiasis in patients treated with octreotide is variable and little is known about gallstone incidence, composition, pathogenetic mechanisms, dissolvability, and primary prevention. Octreotide treatment apart, in industrialised societies most GBS are mixed in composition, cholesterol-rich (arbitrarily greater than 70% cholesterol by weight), radiolucent (70%), and, given a patent cystic duct (70%), dissolvable in bile rendered unsaturated in cholesterol by oral ursodeoxycholic (UDCA) +/- chenodeoxycholic (CDCA) acid treatment. They form when (1) GB bile becomes supersaturated with cholesterol (as the molar ratio of cholesterol to phospholipids in biliary vesicles approaches 1:1, the vesicles become unstable); (2) there is an imbalance between pro- and anti-nucleating factors, which favors cholesterol crystal precipitation; and (3) there is stasis within the GB as a result of altered motor function and/or excess mucus that traps the crystals. These changes may be associated with altered (4) biliary bile acid composition (more DCA and less CDCA than normal), and/or (5) phospholipid fatty acid composition (arachidonyl-rich lecithin acting as a substrate for mucosal prostaglandin synthesis which, in turn, may influence both gallbladder motility, and mucus glycoprotein synthesis and secretion). During octreotide treatment, meal-stimulated cholecystokinin (CCK) release is impaired leading to GB hypomotility, but little is known about the effects of octreotide on biliary cholesterol saturation, crystal nucleation time, mucus glycoprotein concentration, bile acid or phospholipid fatty acid composition. Most, but not all, reports suggest that the prevalence of GBS in octreotide-treated patients is considerably greater than that in age-, sex-, and weight-matched controls, but proof (by pre-treatment and on-treatment ultrasound) that the GBS were absent before, but developed during, therapy is not always available. Furthermore, there are few data on analysis of GBS composition in patients developing stones during treatment, although initial reports suggest that octreotide-associated GBS are also radiolucent, cholesterol-rich, and dissolve with oral bile acid treatment. Maximum GBS attenuation values, measured in Hounsfield Units (HU) by localized computerized tomography scanning of the GB, predict stone composition and dissolvability: GBS with scores of less than 100 HU are cholesterol-rich and dissolve well with oral bile acid treatment. However, preliminary results in 11 acromegalic patients treated with 200 to 600 micrograms octreotide/d for 29 to 68 months show that the HU scores range from 23 to 490 (mean +/- SEM, 116 +/- 41), suggesting that at least four of these 11 patients have non-cholesterol stones.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of small doses of somatostatin analog, octreotide, on gallbladder contractility in normal Chinese adults

The acute effects of single different doses of the somatostatin analog octreotide on the contractility of the gallbladder stimulated by fatty meal were studied in six healthy Chinese volunteers. Gallbladder contraction after a fatty meal was significantly suppressed by octreotide at doses of 50, 25, 12.5, and 5 micrograms. Mean duration of suppression lasted for more than 10 hr at doses of 25 and 50 micrograms, after which the gallbladder contractility was restored at 24 hr in three and four, respectively, of the six subjects. The percentage of relative gallbladder contraction (PRGC) in all subjects receiving 12.5 and 5 micrograms octreotide returned to pretreatment values at 10 hr but had not returned to normal 6 hr after the injection of 5 micrograms octreotide. In summary, octreotide inhibits the contraction of the gallbladder even with a dose as low as 5 micrograms. It appears that it may not be possible to avoid gallbladder dysfunction during long-term octreotide therapy by decreasing the dose. Further studies including modalities to increase the contractility of the gallbladder are recommended.