Sandostatin LAR in acromegalic patients: long-term treatment.

We have evaluated the long term effects and safety of Sandostatin LAR, a long acting formulation of octreotide, during 18 subsequent injections given every fourth week to 14 octreotide-sensitive acromegalic patients. The dosages (20, 30, or 40 mg) were adjusted according to GH response, side-effects, or symptom relief and assessed on day 28 after each injection. We found a stable and consistent suppression of GH and insulin-like growth factor (IGF-I) during the entire study period. Daily mean GH levels were suppressed below 2 micrograms/L in 9, to between 2-5 micrograms/L in 3, and to between 5-10 micrograms/L in 2 patients. The corresponding IGF-I values were suppressed to below 500 micrograms/L in 9 patients and to between 500-1000 micrograms/L in the remaining 5 patients. Increasing the dosage of Sandostatin LAR from 20 to 30 mg had no obvious additional effect on GH suppression, but provided a further decrease in IGF-I levels. Forty milligrams of the drug had no additional effect on GH or IGF-I compared to 30 mg. Acromegalic signs and symptoms improved during treatment. Although the fluctuations of daily mean octreotide levels were high, dosage increments caused an increase in the average serum concentration in the individual patient. Pituitary tumor size reduction was seen in all previously untreated patients (n = 4). We found only minor changes in glucose metabolism (oral glucose tolerance test and hemoglobin A1C) during treatment, but no biologically relevant changes in thyroid function (TSH, T3, and free T4). One patient developed asymptomatic gallstones, and another acquired vitamin B12 deficiency during treatment. The drug is well tolerated during long term treatment. Sandostatin LAR may well be the future medical treatment of choice for acromegalic patients.

Sandostatin LAR in acromegalic patients: a dose-range study.

Sandostatin LAR is a sustained release formulation of octreotide that has been developed by microencapsulating the drug with biodegradable poly(lactide-glycolide)-glucose. We have investigated the efficacy and tolerability of Sandostatin LAR given as a single dose im to patients with active acromegaly who showed good GH suppression during a 2- to 4-week pretreatment period with octreotide given sc. Two double blind studies were performed. Initially, 14 patients were randomized and observed over 42 days after a single im injection of 3, 6, 9, or 12 mg Sandostatin LAR. In the second study, 15 patients were randomized and observed over 60 days after a single im injection of either 20 or 30 mg Sandostatin LAR. Assessments of 12-h GH and octreotide profiles and adverse events were made on day -14 (during treatment with Sandostatin, sc); day 0 (off treatment after wash-out period); days 1, 7, 14, 21, 28, 35, and 42; and, for study 2, also on days 49 and 60 after the im injection. Only injections of 20 or 30 mg were followed by a suppression of basal GH and insulin-like growth factor I to levels comparable to those seen during sc treatment. The suppression of mean GH to less than 5 micrograms/L lasted for 4 weeks in the group receiving 20 mg and for at least 6 weeks in those given 30 mg Sandostatin LAR. The pharmacokinetic profile fitted a biphasic drug release model previously described for peptides in similar drug delivery systems. Serum concentrations correlated with the im administered dose. Suppression of GH and insulin-like growth factor I was achieved at serum octreotide concentrations exceeding approximately 600 ng/L. Tolerability was good. Sandostatin LAR holds promise as a valuable drug for the treatment of acromegaly. The results of ongoing long term studies will provide further necessary knowledge of the drug.

A comparison of octreotide, bromocriptine, or a combination of both drugs in acromegaly.

We investigated the pharmacokinetics of bromocriptine and octreotide, both individually and in combination, in 12 patients with active acromegaly. The pharmacodynamics of the drugs were assessed by 12-h profiles of GH secretion and insulin-like growth factor-I (IGF-I) measurements. During the 42-day study period, bromocriptine was administered for 28 days (from day 8; 5 mg, orally, twice daily) and octreotide (200 micrograms, sc, twice daily) from days 15-42. IGF-I levels, 12-h GH, and plasma bromocriptine and octreotide profiles were obtained on days 0, 14, 28, and 42. During bromocriptine treatment, both the area under the GH day curves (AUC) and mean IGF-I decreased to 64% (95% confidence limits, 43-72% and 48-82%, respectively) of initial values. During octreotide treatment, the respective values were 23% (18-30%) and 32% (21-36%), which were greater decreases than those during bromocriptine treatment [36% (95% confidence limits, 32-54%) for AUC for GH and 50% (95% confidence limits, 34-58%) for IGF-I]. With combined treatment, the AUC for GH was reduced to 16% (12-21%) and that of IGF-I to 25% (16-27%) of initial values. This combination was more effective than bromocriptine [25% (95% confidence limits, 22-37%) for AUC for GH and 39% (95% confidence limits, 25-43%) for IGF-I] and octreotide alone [78% (95% confidence limits, 53-89%) for AUC for GH and 78% (95% confidence limits, 57-98%) for IGF-I]. The pharmacokinetic parameters of octreotide were unchanged by the coadministration of bromocriptine. The bioavailability of bromocriptine increased by approximately 40% when bromocriptine was administered together with octreotide compared with administration alone (P < 0.01). Bromocriptine disposition parameters were unaltered. In conclusion, treatment of acromegalics with a combination of octreotide and bromocriptine increases the bioavailability of bromocriptine and reduces both GH and IGF-I levels more effectively than treatment with either drug alone. This presents the possibility of less frequent drug administrations, lower doses of octreotide, and, consequently, lower treatment costs.