OCTREOTIDE LONG-TERM TREATMENT OF ACROMEGALY - EFFECT OF DRUG-WITHDRAWAL ON SERUM GROWTH-HORMONE INSULIN-LIKE GROWTH FACTOR-I CONCENTRATIONS AND ON SERUM GASTRIN 24-HOUR INTRAGASTRIC PH VALUES/

We studied a possible persistence of low GH concentrations after drug withdrawal in eight acromegalic patients who had been receiving octreo tide treatment continuously for 42 months. Since octreotide induces ch ronic active gastritis, intragastric pH and serum gastrin were also de termined before and during drug withdrawal. Results were compared to t he respective pretreatment (pre-Tx) values. GH and insulin-like growth factor-I (IGF-I) increased after 4 weeks of octreotide withdrawal to pre-Tx values (GH, 12-h profile, 4.5 +/- 0.6, 2.6 +/- 0.7, and 5.6 +/- 1.1 mug/L; IGF-I, three samples, 3.4 +/- 0.4, 0.8 +/- 0.1, and 2.5 +/ - 1.0 IU x 10(3)/L; means +/- SE, pre-Tx, on and off octreotide). A re duced insulin and augmented glucose response to oral glucose during th erapy normalized after octreotide withdrawal (insulin, 527 +/-84, 289 +/- 62, and 733 +/- 110 pmol/L; glucose, 6.2 +/- 0.3, 8.5 +/- 0.4, and 6.8 +/- 0.2 mmol/L; Pre-Tx, on and off octreotide, means +/- SE). Dur ing octreotide treatment, the median 24-h intragastric pH value was 2. 8 (pre-Tx pH not determined), and the median serum gastrin concentrati on (areas under the curve of 12-h profiles) was 1275 +/- 153 ng/L . 12 h (n = 7). During octreotide withdrawal, pH decreased to 1.4, while s erum gastrin increased to a median of 2937 +/- 472 ng/L . 12 h. We con clude that GH and IGF-I suppression by long term octreotide therapy do es not persist after drug withdrawal, indicating a need for life-long treatment. Octreotide-induced insulin suppression and glucose elevatio n are reversible. A high gastric pH during treatment may facilitate th e development of octreotide-related gastritis. The gastrin increase du ring octreotide withdrawal probably reflects a response to chronic act ive gastritis after release from octreotide-induced gastrin inhibition .