Octreotide

Octreotide

REF: Goodman and Gillman 11^th ed p. 635

Octreotide inhibits the release of hormones (triggered by rapid passage of food into the small intestine) that are responsible for distressing local and systemic effects.

Octreotide has been used, with varying success, in other forms of secretory diarrhea such as

1. Chemotherapy-induced
2. Diarrhea associated with human immunodeficiency virus (HIV)
3. Diabetes-associated diarrhea.
4. Its greatest utility is in the “dumping syndrome” seen in some patients after gastric surgery and pyloroplasty

Glioma [Ref: Harrison 17/e p 2355, 2353, 2211, 2014, 1977; KDT 6/e p 577; Katzung 11/c p 1081] Octreotide is a synthetic analogue of somatostatin and its pharmacological actions are similar to somatostatin.

Somatostatin

• Somatostatin is a hypothalamic peptide that regulates the function of several endocrine and exocrine glands.
• Somatostatin acts primarily as a negative regulator of a variety of different types of cells blocking processes such as cell secretion, cell growth and smooth muscle contraction.
• It is secreted from the hypothalamus into the portal circulation and travels to the anterior pituitary gland where it inhibits the production and release of both growth hormone and thyroid stimulating hormone.
• Somatostatin is present in many tissues other than hypothalamus

It is also secreted by the cells in the pancreas and in the intestine where it inhibits the secretion of variety of hormones

Glucagonoma

Octreotide is a synthetic analogue of Somatostatin which is administered sub-cutaneously, intra-muscularly or intra-venously but not available in the oral form.

Ref: Basic and Clinical Pharmacology By Bertram G. Katzung ,10th Edition, Pages 605, 1024; K D Tripathi Textbook of Pharmacology, 5th Edition, Pages 217, 622

Antibiotic, corticosteroids, H2 blockers and NSAIDS also have a role.

Somatostatin and the synthetic longer lasting analogue OCTREOTIDE are now the first choice for the pharmacological control of acutely bleeding varices.

Ref: CMDT 2008 Edition, Page 559-560

Ans. is ‘b’ i.e., Octreotide

Ans. is ‘c’ i.e., Infective diarrhea

Ans. C: Contraindicated in Acromegaly

Salt form of this peptide, octreotide acetate, is used as an injectable depot formulation for the treatment of acromegaly, the treatment of secretory diarrhea and flushing episodes associated with carcinoid syndrome, and treatment of diarrhea in patients with vasoactive intestinal peptide-secreting tumors (VlPomas).

Octreotide has also been used off-label for the treatment of severe, refractory diarrhea from other causes. It is used in toxicology for the treatment of prolonged recurrent hypoglycemia after sulfonylurea and possibly meglitinides overdose. Octreotide has also been used with varying degrees of success in infants with nesidioblastosis to help decrease insulin hypersecretion.

In patients with suspected esophageal varices, octreotide can be given to help decrease bleeding.

Octreotide may be useful in the treatment of thymic neoplasms.

It has been used in the treatment of malignant bowel obstruction.

Octreotide may be used in conjunction with midodrine to partially reverse peripheral vasodilation in the hepato-renal syndrome. By increasing systemic vascular resistance, these drugs reduce shunting and improve renal perfusion, prolonging survival until definitive treatment with liver transplant.

Ans. a. Carbamazepine

Carbamazepine: (The indication of carbamazepine was not mentioned in the question in the exam)

• Most effective drug for complex partial seizurese.
• Generalized tonic clonic and simple partial seizures
• DOC in Trigeminal neuralgiae.
• As an alternative to lithium in manic depressive illness and acute maniac

Octreotide:

• An octapeptide analog of somatostatin
• Effective in inhibiting the severe secretory diarrhea brought about by hormone-secreting tumours of the pancreas and the GI tract.

Desmopressin:

• Used in central diabetes insipidus, nocturnal enuresis, nighttime urination and von-Willebrands disease
• Also used in diagnostic work-up for diabetes insipidus, in order to distinguish central from nephrogenic DI.

Human Chorionic Gonadotropin (hCG):

In Women

• LH and FSH are needed for egg production (ovulation).
• Early in the menstrual cycle, a woman with low hormone levels who is not ovulating can have daily human menopausal gonadotropin (hMG) or recombinant human FSH (rFSH) injections for an average of 12 days.
• If this helps develop mature follicles, the ovary is ready to ovulate.
• One dose of human chorionic gonadotropin (hCG) is then used to stimulate ovulation.
• In Men with Low Testosterone and FSH
• LH stimulates the production of testosterone, and FSH promotes the formation of sperm.
• If a semen analysis, LH testing, and FSH testing suggest that abnormal hormone levels are preventing sperm production, these gonadotropins may be prescribed together to promote sperm formation.
• The man gets an hCG injection 3 times weekly until blood testosterone levels is within the normal range (this may take 4 to 6 months).
• Treatment continues with injections of hCG 2 times a week and hMG or FSH 3 times a week until the sperm count rises to normal levels.

Carbamazepine

• It is chemically related to imipramine and teratogenice.
• Acts by prolongation of inactive Na^. channelse.
• Water retention and hyponatremia can occur in the elderly as it enhances ADH actione.
• On chronic administration, it induces its own metabolism^s like phenobarbitone. Side effects:
• MC dose-related adverse effects: Diplopia and ataxiae.
• Other dose-related complaints: mild gastrointestinal upsets, unsteadiness, and, at much higher doses, drowsiness
• Hyponatremia and water intoxication^s have occasionally occurred and may be dose- related
• Considerable concern exists regarding the occurrence of idiosyncratic blood dyscrasias^e with carbamazepine, including fatal cases of aplastic anemia and agranulocytosise.
• MC idiosyncratic reaction is an erythematous skin rashe

Uses:

• Most effective drug for complex partial seizurese.
• Generalized tonic clonic and simple partial seizures
• DOC in Trigeminal neuralgiae
• As an alternative to lithium in manic depressive illness and acute maniac