Octreotide. Chemical name: D-Phenylalanyl-L-cysteinyl-L-phenylalanyl-D-tryptophyl-L-lysyl-L- threonyl-N-[2-hydroxy-1-(hydroxymethyl)propyl]-L-cysteinamide cyclic (2 7) - disulfide
Sandostatin is octreotide, a synthetic octapeptide analogue of somatostatin. where x = 1.4 to 2.5
O O CH2
CH2 CH
C NH CH C
NH CH C NH
O CH
C NH CH
CH2
NH
O
(CH2)4 NH2
HO CH2 CH NH C
CH NH C C NH C
O CH O
.x acetate
HO CH3
CH3 OH CAS number: 79517-01-4. (octreotide acetate) MW: 1019.3 (free peptide) Each 1 mL ampoule contains 0.05 mg, 0.1 mg or 0.5 mg octreotide (present as acetate). The solution is clear and colourless.
lactic acid, mannitol, sodium bicarbonate, water for injections.
Pharmacodynamics
Octreotide is a synthetic octapeptide analogue of naturally occurring somatostatin with similar pharmacological effects, but with a considerably prolonged duration of action. It inhibits the secretion of serotonin and the gastro-entero-pancreatic peptides: gastrin, vasoactive intestinal peptide, insulin, glucagon, secretin, motilin, and pancreatic polypeptide, and of growth hormone (GH). Sandostatin, like somatostatin, decreases splanchnic blood flow. In animals, octreotide is a more potent inhibitor of growth hormone, glucagon and insulin release than somatostatin with greater selectivity for GH- and glucagon-suppression. In healthy subjects octreotide, like somatostatin, has been shown to inhibit: release of growth hormone (GH) stimulated by arginine, exercise and insulin-induced hypoglycaemia postprandial release of insulin, glucagon, gastrin, other peptides of the GEP system, and arginine-stimulated release of insulin and glucagon thyrotropin releasing hormone (TRH) stimulated release of thyroid stimulating hormone (TSH). Unlike somatostatin, octreotide inhibits GH secretion preferentially over insulin and its administration is not followed by rebound hypersecretion of hormones (i.e. GH in patients with acromegaly). In patients with acromegaly (including those who have failed to respond to surgery, radiation or dopamine agonist treatment), Sandostatin lowers plasma levels of GH and Insulin-like Growth Factor-1/Somatomedin C (IGF-1). A reduction in plasma GH (by 50% or more) occurs in almost all patients, and a plasma GH < 5 ng/mL can be achieved in about half of the cases. Most patients with symptoms such as headache, skin and soft tissue swelling, hyperhidrosis, arthralgia, paraesthesia report a reduction in these symptoms. In patients with a large pituitary adenoma, Sandostatin treatment may result in some shrinkage of the tumour mass. In patients with functional tumours of the gastro-entero-pancreatic endocrine system, Sandostatin, because of its diverse endocrine effects, modifies different clinical features. Clinical improvement and symptomatic benefit occur in patients who have severe symptoms related to their tumours despite previous therapies which include surgery, hepatic artery embolisation and various chemotherapies, e.g. streptozotocin and 5-fluorouracil. Sandostatin's effects in the different tumour types are as follows:
Carcinoid tumours:
Administration of Sandostatin may result in improvement of symptoms, particularly of flush episodes and severe diarrhoea. In some cases this is accompanied by a fall in plasma serotonin and reduced urinary excretion of 5-hydroxyindole acetic acid. In the event of no beneficial response to Sandostatin treatment, continuation of therapy beyond one week at the maximum tolerated dose is not recommended, although in non-responders no serious sustained adverse drug effects have been reported.
Vasoactive intestinal peptide secreting tumours (VIPomas):
The biochemical characteristic of these tumours is overproduction of vaso-active intestinal peptide (VIP). In most cases, administration of Sandostatin results in alleviation of the severe secretory diarrhoea typical of the condition, with consequent improvement in quality of life. This is accompanied by an improvement in associated electrolyte abnormalities, e.g. hypokalaemia, enabling enteral and parenteral fluid and electrolyte supplementation to be withdrawn. In some patients, computer tomography scanning suggests a slowing or arrest of progression of the tumour, or even tumour shrinkage, particularly of hepatic metastases. Clinical improvement is usually accompanied by a reduction in plasma VIP levels, which may fall into the normal reference range. In patients with carcinoid syndrome and VIPomas, the effect of Sandostatin LAR on tumour size, rate of growth and development of metastases, has not been determined. For patients undergoing pancreatic surgery, the peri- and post-operative administration of Sandostatin reduces the incidence of typical post-operative complications (e.g. pancreatic fistula, abscess and subsequent sepsis, post-operative acute pancreatitis). A large multi-centre study in patients with acute bleeding due to gastric or duodenal ulcer showed no benefit of Sandostatin over placebo in the control of haemorrhage.
Pharmacokinetics
Absorption:
After subcutaneous injection, octreotide is absorbed rapidly and completely from the injection site. Peak concentrations of 5.5 ng/mL (100 microgram dose) were reached 0.4 hours after dosing. In a single dose study, the absolute bioavailability after s.c. administration was found to be significantly different for different doses, however the interindividual variability was large. Relative to an equivalent intravenous dose, the bioavailability of a subcutaneous dose was estimated to be 80-135%. This was established based on the respective plasma concentrations determined by a radioimmunoassay. Peak concentrations and area under the curve values were dose proportional both after s.c. or i.v. single doses up to 400 mcg and with multiple doses of 200 mcg t.i.d. (600 mcg/day). Clearance was reduced by about 66% suggesting non-linear kinetics of the drug at daily doses of 600 mcg/day as compared to 150 mcg/day. The relative decrease in clearance with doses above 600 mcg/day is not defined.
The distribution of octreotide from plasma was rapid (t1/2 = 0.2 h) and the volume of distribution after i.v. dosing was estimated to be 0.27 L/kg body weight. In blood, the distribution into the erythrocytes was found to be negligible and about 65% was bound in the plasma in a concentration-independent manner. Binding was mainly to lipoprotein and, to a lesser extent, to albumin.
The elimination of octreotide from plasma had an apparent half-life of 1.5 hours compared with 1 to 3 minutes with the natural hormone. The duration of action of Sandostatin is variable but extends up to 12 hours depending upon the type of tumour. About 32% of the dose is excreted unchanged into the urine.
Impaired renal function did not affect the total exposure (AUC) to octreotide administered as a subcutaneous injection. Therefore, no dose adjustment is necessary. In patients with severe renal failure requiring dialysis, clearance was reduced to about half that found in normal subjects (from approximately 10 L/h to 4.5 L/h). The elimination capacity may be reduced in patients with liver cirrhosis (see "PRECAUTIONS - Use in patients with impaired hepatic function"), but not in patients with fatty liver disease.
For symptomatic control and reduction of growth hormone and IGF-1 plasma levels in patients with acromegaly, including those who are inadequately controlled by surgery, radiotherapy, or dopamine agonist treatment. Sandostatin treatment is also indicated in acromegalic patients unfit or unwilling to undergo surgery, or in the interim period until radiotherapy becomes fully effective. For the relief of symptoms associated with the following functional tumours of the gastro-entero-pancreatic endocrine system: -Carcinoid tumours with features of the carcinoid syndrome -Vasoactive intestinal peptide secreting tumours (VIPomas). Sandostatin is not curative in these patients. For reduction of the incidence of complications following pancreatic surgery.
Hypersensitivity to octreotide or to any component of the formulation.
Uncommon cases of bradycardia have been reported. Medical review including dose adjustment of this agent and dose adjustments of drugs such as beta-blockers, calcium channel blockers, or agents to control fluid and electrolyte balance, may be necessary.
Development of gallstones has been reported in 15-30% of long-term recipients of Sandostatin. The prevalence in the general population (aged 40 to 60 years) is estimated from reviews to be about 5-20%. Ultrasonic examination of the gallbladder before and at 6 to 12 monthly intervals during Sandostatin therapy is therefore recommended. If gallstones do occur, they are usually asymptomatic; symptomatic stones should be treated either by dissolution therapy with bile acids or by surgery.
As GH secreting pituitary tumours may sometimes expand, thereby causing serious complications (e.g. visual field defects), it is essential that all patients be carefully monitored. If evidence of tumour expansion appears, alternative procedures may be advisable.
In the treatment of gastro-entero-pancreatic endocrine tumours sudden escape from symptomatic control by Sandostatin may occur infrequently, with rapid recurrence of severe symptoms.
In patients with concomitant hypersecretion of insulin, Sandostatin, because of its greater relative potency in inhibiting secretion of growth hormone and glucagon than of insulin, and its shorter duration of action on inhibition of the latter, may increase the depth of, and prolong the duration of hypoglycaemia. Such patients should be closely observed on introduction of Sandostatin therapy and at each change of dosage. Marked fluctuations of blood glucose concentration may possibly be reduced by more frequent administration of Sandostatin. Patients with type I diabetes mellitus requiring insulin therapy may have their insulin requirements reduced by administration of Sandostatin. In non-diabetic patients and patients with type II diabetes mellitus who have partially intact insulin reserves, Sandostatin administration can result in prandial increases in glycaemia (see "ADVERSE REACTIONS"). It is therefore recommended to monitor glucose tolerance and antidiabetic treatment.
Sandostatin administration to patients who have concomitant bleeding gastro-oesophageal varices due to underlying hepatic cirrhosis increases the risk of development of insulin- dependent diabetes or of changes in insulin requirements in the presence of pre-existing diabetes. Therefore, appropriate monitoring of blood glucose levels is mandatory.
Octreotide may alter absorption of dietary fats in some patients. Depressed vitamin B12 levels and abnormal Schilling's tests have been observed in some patients receiving ocreotide therapy. Monitoring of vitamin B12 levels is recommended during therapy with Sandostatin in patients who have a history of vitamin B12 deprivation.
Thyroid function should be monitored in patients receiving prolonged treatment with octreotide.
Impaired renal function did not affect the total exposure (AUC) to octreotide when administered subcutaneously. Therefore, no dose adjustment of Sandostatin is necessary.
In patients with liver cirrhosis, the half-life of the drug may be increased. If this occurs, adjustment of the maintenance dose may be considered.
In elderly patients treated with Sandostatin, there was no evidence for reduced tolerability or altered dosage requirements.
Experience with Sandostatin in children is very limited.
In repeat dose toxicity studies in rats of 52 weeks duration and longer, predominantly in males, sarcomas were noted at the subcutaneous injection site of octreotide in an acidic vehicle and at a lower incidence with the acidic vehicle alone. These did not occur in a mouse carcinogenicity study, nor did hyperplastic or neoplastic lesions occur at the subcutaneous injection site in a 52-week dog toxicity study. The 116-week rat carcinogenicity study also revealed uterine endometrial adenocarcinomas, their incidence reaching statistical significance at the highest dose of 1.25 mg/kg per day. There have been no reports of tumour formation at the injection sites in patients treated for up to 15 years with Sandostatin. All information available at present indicates that the finding of injection site sarcomas in rats is species-specific and has no significance for the use of the drug in humans. The presence of endometritis coupled with the absence of corpora lutea, the reduction in mammary fibroadenomas, and the presence of uterine dilatation suggest that the uterine tumours were associated with oestrogen dominance in the aged female rats which does not occur in humans.
Reproduction studies have been performed in rats and rabbits at doses up to 1 mg/kg and have revealed no evidence of any adverse effect of Sandostatin on fertility or morphogenesis. Foetal and post-natal growth retardation was seen in rats, probably due to suppression of growth hormone. There are no adequate and well-controlled studies in pregnant women. In the post-marketing experience, data on a limited number of exposed pregnancies have been reported in patients with acromegaly, however, in half of the cases the pregnancy outcomes are unknown. Most women were exposed to octreotide during the first trimester of pregnancy at doses ranging from 100 to 300 micrograms/day of Sandostatin s.c. or 20 to 30 mg/month of Sandostatin LAR. In approximately two-thirds of the cases with known outcome, the women elected to continue octreotide therapy during their pregnancies. In most of the cases with known outcome, normal newborns were reported but also several spontaneous abortions during the first trimester, and a few induced abortions. There were no cases of congenital anomalies or malformations due to octreotide usage in the cases that reported pregnancy outcomes. Sandostatin should only be prescribed to pregnant women under compelling circumstances. The therapeutic benefits of a reduction in growth hormone (GH) levels and normalization of insulin-like growth factor 1 (IGF-1) concentration in female acromegalic patients could potentially restore fertility. Female patients of childbearing potential should be advised to use adequate contraception if necessary during treatment with octreotide.
It is unknown whether octreotide is excreted in human breast milk. Animal studies have shown excretion of octreotide in breast milk. Patients should not breast-feed during Sandostatin treatment.
Interactions with Other Drugs
Many patients with carcinoid syndrome or VIPomas being treated with Sandostatin have also been, or are being, treated with many other drugs to control the symptomatology or progression of the disease, including chemotherapeutic agents, H2 antagonists, antimotility agents, drugs affecting glycaemic states, solutions for electrolyte and fluid support or hyperalimentation, antihypertensive diuretics and anti-diarrhoeal agents. Octreotide has been reported to produce a reduction in the intestinal absorption of cyclosporin, and a delay in that of cimetidine. Concomitant administration of octreotide and bromocriptine increases the bioavailability of bromocriptine. Limited published data indicate that somatostatin analogs might decrease the metabolic clearance of compounds known to be metabolised by cytochrome P450 enzymes, possibly due to the suppression of growth hormone. Since it cannot be excluded that octreotide may have this effect, other drugs which are mainly metabolised by CYP3A4 and which have a low therapeutic index ( e.g. quinidine) should be used with caution. Since octreotide has also been associated with alterations in nutrient absorption, its effect on absorption of any orally administered drugs should be carefully considered. Where symptoms are severe and Sandostatin therapy is added to other therapies used to control glycaemic states such as sulphonylureas, insulin, diazoxide, and to beta blockers or agents for the control of fluid and electrolyte balance, patients must be monitored closely and adjustment made in the other therapies as the symptoms of the disease are controlled. Evidence currently available suggests these imbalances in fluid and electrolytes or glycaemic states are secondary to correction of pre-existing abnormalities and not to a direct metabolic action of Sandostatin. Adjustment of the dosage of drugs, such as insulin, affecting glucose metabolism may be required following initiation of Sandostatin therapy in patients with diabetes (see "PRECAUTIONS-Effects on glucose regulation").
The most frequent adverse reactions reported during octreotide therapy include gastrointestinal disorders, nervous system disorders, hepatobiliary disorders, and metabolism and nutritional disorders. The most commonly reported adverse reactions in clinical trials with octreotide administration were diarrhoea, abdominal pain, nausea, flatulence, headache, cholelithiasis, hyperglycaemia and constipation. Other commonly reported adverse reactions were dizziness, localised pain, biliary sludge, thyroid dysfunction (e.g. decreased thyroid stimulating hormone [TSH], decreased Total T4, and decreased Free T4), loose stools, impaired glucose tolerance, vomiting, asthenia, and hypoglycaemia. Local reactions may occur and include pain, a sensation of stinging, tingling or burning at the site of injection, with redness, swelling, irritation and rash. They rarely last more than fifteen minutes. Local discomfort may be reduced by allowing the solution to reach room temperature before injection or by injecting a smaller volume using a more concentrated solution. Although measured faecal fat excretion may increase, there is no evidence to date that long- term treatment with octreotide has led to nutritional deficiency due to malabsorption. In rare instances, gastrointestinal side effects may resemble acute intestinal obstruction, with progressive abdominal distension, severe epigastric pain, abdominal tenderness and guarding. Occurrence of gastrointestinal side effects may be reduced by avoiding meals around the time of Sandostatin administration, that is, by injecting between meals or on retiring to bed. Acute pancreatitis has been reported in rare instances. Generally, the effect is seen within the first hours or days of Sandostatin treatment and resolves on withdrawal of the drug. In addition, pancreatitis may develop in patients on long-term Sandostatin treatment who develop gallstones. In both acromegalic and carcinoid syndrome patients arrhythmia and ECG changes such as QT prolongation, axis shifts, early repolarisation, low voltage, R/S transition, early R wave progression and non-specific ST-T wave changes were observed. The relationship of these events to octreotide acetate is however not established because many of these patients have underlying cardiac diseases (see PRECAUTIONS). Adverse drug reactions (see table below) are ranked under heading of frequency, the most frequent first, using the following convention: very common (>= 1/10); common (>= 1/100, < 1/10); uncommon (>= 1/1,000, < 1/100); rare (>= 1/10,000, < 1/1,000) very rare (< 1/10,000), including isolated reports. Within each frequency grouping, adverse reactions are ranked in order of decreasing seriousness.
Adverse drug reactions reported in clinical studies
| Gastrointestinal disorders | |
| Very common: | Diarrhoea, abdominal pain, nausea, constipation, flatulence. |
| Common: | Dyspepsia, vomiting, abdominal bloating, steatorrhoea, loose stools, discolouration of faeces. |
| Nervous system disorders | |
| Very common: | Headache. |
| Common: | Dizziness. |
| Endocrine disorders | |
| Common: | Hypothyroidism, thyroid dysfunction (e.g. decreased TSH, decreased Total T4, and decreased Free T4). |
| Hepatobiliary disorders | |
| Very common: | Cholelithiasis. |
| Common: | Cholecystitis, biliary sludge, hyperbilirubinaemia. |
| Metabolism and nutrition disorders * | |
| Very common: | Hyperglycaemia. |
| Common: | Hypoglycaemia, impaired glucose tolerance, anorexia. |
| Uncommon: | Dehydration. |
| General disorders and administration site | |
| Very common: | Localised pain at injection site. |
| Investigations | |
| Common: | Elevated transaminase levels. |
| Skin and subcutaneous tissue disorders | |
| Common: | Pruritus, rash, alopecia. |
| Respiratory disorders | |
| Common: | Dyspnoea. |
| Cardiac disorders | |
| Common: | Bradycardia. |
| Uncommon: | Tachycardia. |
* Because of its inhibitory action on growth hormone, glucagon and insulin release, Sandostatin LAR may affect glucose regulation. Post-prandial glucose tolerance may be impaired. As reported for patients treated with
s.c. Sandostatin, in some instances, a state of persistent hyperglycaemia may be induced as a result of chronic administration.
Flushing and oedema, events attributable to the underlying condition, have been observed.
Post-Marketing Experience
Spontaneously reported adverse reactions, presented in the table below, are reported voluntarily and it is not always possible to reliably establish frequency or a causal relationship to drug exposure.
Adverse drug reactions derived from spontaneous reports
| Immune disorders | Anaphylaxis, allergy/hypersensitivity reactions. |
| Skin and subcutaneous tissue disorders | Urticaria. |
| Hepatobiliary disorders | Acute pancreatitis, acute hepatitis without cholestasis *, cholestatic hepatitis, cholestasis, jaundice, cholestatic jaundice. |
| Cardiac disorders | Arrhythmias. |
| Investigations | Increased alkaline phosphatase levels, increased gamma glutamyl transferase levels. |
*
where there has been normalisation of transaminase values on withdrawal of subcutaneous octreotide
Initially 0.05-0.1 mg by subcutaneous injection every 8 or 12 hours. Dosage adjustment should be based on monthly assessment of GH and IGF-1 levels (target: GH <2.5 ng/mL; IGF-1 within normal range) and on clinical symptoms, and on tolerability. In most patients the optimal daily dose will be 0.2 to 0.3 mg. A maximum dose of 1.5 mg per day should not be exceeded. For patients on a stable dose of Sandostatin, assessment of biochemical markers should be made periodically. If no relevant reduction of GH levels and no improvement of clinical symptoms have been achieved within three months of starting treatment with Sandostatin, therapy should be discontinued.
Initially 0.05 mg once or twice daily by subcutaneous injection. Depending on clinical response, the effect on levels of circulating tumour products, and on tolerability, dosage can be gradually increased to 0.2 mg 3 times daily. Under exceptional circumstances higher doses may be required, however experience with doses above 750 mcg per day is limited. Maintenance doses can be variable, depending on differences in tumour activity and rate of progression.
0.1 mg three times daily by subcutaneous injection for seven consecutive days, starting on the day of operation at least one hour before laparotomy.
Patients who are to self-administer the drug by subcutaneous injection must receive precise directions from the physician or the nurse. To reduce local discomfort, it is recommended that the solution reaches room temperature before injection. Multiple injections at short intervals at the same site should be avoided. Ampoules should be opened just prior to administration and any unused portion discarded. Parenteral drug products should be inspected visually for particulate matter and discolouration prior to administration. Do not use if particulates and/or discolouration are observed.
In elderly patients treated with Sandostatin, there was no evidence for reduced tolerability or altered dosage requirements.
Experience with Sandostatin in children is very limited.
A limited number of accidental overdoses of Sandostatin LAR have been reported. The doses ranged from 100 mg to 163 mg/month of Sandostatin LAR. The only adverse event reported was hot flushes. Cancer patients receiving doses of Sandostatin LAR up to 60 mg/month and up to 90 mg/2 weeks have been reported. These doses were in general well tolerated; however, the following adverse events have been reported: frequent urination, fatigue, depression, anxiety, and lack of concentration.
The management of overdosage is symptomatic. Contact the Poisons Information Centre on 13 11 26 for advice on management.
0.05 mg in 1 mL - box of 5
0.1 mg in 1 mL - box of 5 0.5 mg in 1 mL - box of 5 Schedule: 4
Store at 2-8degC (Refrigerate. Do not freeze). Protect from light. For day- to-day use Sandostatin may be stored at room temperature (below 30degC) for up to 2 weeks.
Any ampoules unused after this period out of the refrigerator should be discarded.
NOVARTIS Pharmaceuticals Australia Pty Limited ABN 18 004 244 160 54 Waterloo Road NORTH RYDE, NSW 2113
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Approved by the Therapeutic Goods Administration: 7 August 2009