Medications
Medical therapy is directed toward the specific endocrine syndromes.
Sandostatin acts similarly to the natural hormone somatostatin by suppressing peptide secretion from gastroenteropancreatic tumors.
Octreotide acetate (Sandostatin)
Primarily acts on somatostatin receptor subtypes II and V. Inhibits GH secretion, and other endocrine and nonendocrine effects, including inhibition of glucagon, VIP, and GI peptides. Controls diarrhea in 80% of patients. Progressive increases in dosage may be necessary.
Dosing Adult
50 mcg SC q12h initially; may increase dose to 200-300 μ g/d, based on tolerability and response
Pediatric
200-300 μ g/d SC divided bid/qid during initial 2 wk; individual dosage adjustment prn to control symptoms
Interactions
Associated with altered nutrient absorption; consider effect on PO drug absorption; may reduce effects of cyclosporine; patients taking insulin, PO hypoglycemics, beta-blockers, and calcium channel blockers may require dosage adjustments
Contraindications Precautions
Pregnancy – Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Adverse effects are primarily related to altered GI motility, including nausea, abdominal pain, diarrhea, and increased incidence of gallstones and biliary sludge; because of alteration in counterregulatory hormones (eg, insulin, glucagon, GH), hypoglycemia or hyperglycemia may be observed; bradycardia, cardiac conduction abnormalities, and arrhythmias have been reported;
because of inhibition of thyroid-stimulating hormone (TSH) secretion, hypothyroidism may also occur; exercise caution in patients with renal impairment; cholelithiasis may occur; possibility of GH suppression requires monitoring of children’s growth
Gastric acid secretion with PPIs is mandatory to prevent complications of gastric acid hypersecretion. PPIs are safe and cause no adverse effects even after long-term use. The goal is to reduce the basal acid output to levels less than 10 mEq/h 1 hour before the next dose in patients without previous acid-reducing gastric surgery and to kess than 5 mEq/h in patients with previous acid-reducing gastric surgery.
Omeprazole (Prilosec)
Substituted benzimidazole that suppresses acid secretion by specifically inhibiting the H+/K+ ATPase at the secretory surface of parietal cell.
20-60 mg/d PO initially; if >80 mg/d, administer in divided doses
Pediatric
Not established. Suggested dosing: Administer as in adults; dose must be adjusted to the individual BAO
Interactions
Prolongs elimination of diazepam, warfarin, and phenytoin; theoretically interferes with absorption of drugs for which gastric pH important determinant of bioavailability (eg, ampicillin esters); may decrease effects of itraconazole or ketoconazole
Contraindications Pregnancy
Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
ECL cell tumors in stomach observed in rats; long-term data not available; headache, diarrhea, and abdominal pain may occur
These agents inhibit insulin release from the tumor.
Diazoxide (Proglycem)
Binds sulfonylurea receptor (SUR1) of the pancreatic beta cell, inhibiting insulin secretion. PO form opens K ATP channels and inhibits insulin secretion. Increases blood glucose level within 1 h by inhibiting insulin release from insulinoma. Unlike rapid IV administration, PO not antihypertensive.
Pediatric Interactions
May decrease serum hydantoin levels, possibly decreasing anticonvulsant effects; thiazide diuretics may potentiate hyperuricemic and hypoglycemic effects
Contraindications
Documented hypersensitivity; functional hypoglycemia
Pregnancy
Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Start only under close clinical supervision; prolonged treatment requires regular monitoring of urine for sugar and ketones; blood sugar levels should be monitored for dose adjustments; plasma half-life prolonged in impaired renal function; lanugo-type thick hair growth occurs in children in frontotemporal areas, extremities, and back; may cause sodium retention with edema
Reprinted with permission from eMedicine.com, 2008.