Clinical and biochemical response following withdrawal of a long-acting, depot injection form of octreotide (Sandostatin-LAR).
OBJECTIVE
Monthly injections of Sandostatin-LAR have been shown to be an effective therapy for patients with acromegaly. Because of an ongoing need to assess a patients response to definitive therapy such as surgery and/or radiotherapy, we aimed to evaluate GH levels and acromegaly symptom scores in patients withdrawing from Sandostatin-LAR.


METHODS
12 patients with acromegaly previously treated with Sandostatin-LAR, 20-40 mg intramuscularly every 28 (n = 9) or 42 (n = 3) days for 12-36 months were studied at monthly intervals for 4 months following the withdrawal of the drug.


METHODS
Hourly fasting serum GH measurements between 0800 h and 1200 h, serum IGF-1 and symptom scores were undertaken at 4, 8, 12 and 16 weeks following the last injection of Sandostatin-LAR. MRI/CT scans of the pituitary were undertaken at 16 weeks and compared to scans taken on Sandostatin-LAR within the previous 10 months.


RESULTS
Serum GH rose progressively from 7.7 (1.5 to 14.6) (median (range)) mIU/l at 4 weeks to 9.9 (1.5-21.8), to 12.6 (4.9-31.9) (P < 0.05 vs 4 weeks) and to 13.1 (6.0-39.1) mIU/l (P < 0.002) at 8, 12 and 16 weeks, respectively, following cessation of Sandostatin-LAR. IGF-1 rose from 38.5 (12.6-73.8) nmol/l at 4 weeks to 62.4 (37.4-159) at 16 weeks (P < 0.002) and mean symptom score (comprising headache, sweating, arthralgia, paraesthesiae, tiredness) from 4.0 (0 to 10) (4 weeks) to 4.5 (0-9) (8 weeks) to 6.0 (2-10) (12 weeks) to 6.5 (4-12) (16 weeks, P < 0.05). Individual GH profiles indicated a rise in GH in 5/12 patients between weeks 4-8 and between weeks 8-12 in a further 5/12 patients. There were no changes in pituitary tumour size following discontinuation of Sandostatin-LAR.


CONCLUSIONS
GH and symptom scores rise progressively following discontinuation of Sandostatin-LAR in acromegalic patients. However, GH and symptom scores remain suppressed in some patients for at least 8 weeks following cessation of Sandostatin-LAR. We suggest that a withdrawal period of 3 months from Sandostatin-LAR is required in order to perform a meaningful re-assessment of GH and clinical status.
Stewart
P M
PM
Department of Medicine, University of Birmingham, Queen Elizabeth Hospital, UK.
Stewart
S E
SE
Clark
P M
PM
Sheppard
M C
MC
D000172:Acromegaly / Q000097:blood / Q000188:drug therapy* / Q000209:etiology; D000328:Adult; D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage* / Q000627:therapeutic use; D003692:Delayed-Action Preparations; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D007279:Injections, Subcutaneous; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D008875:Middle Aged; D015282:Octreotide / Q000008:administration & dosage* / Q000627:therapeutic use; D010911:Pituitary Neoplasms / Q000097:blood / Q000150:complications / Q000188:drug therapy; D013997:Time Factors; D016896:Treatment Outcome
D018931:Antineoplastic Agents, Hormonal; D003692:Delayed-Action Preparations; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D015282:Octreotide