Properties
Tenomet® inhibits basal and nocturnal gastric acid secretion by competitive inhibition of the action of histamine at the histamine H2-receptors of the parietal cells. Tenomet® also inhibits gastric acid secretion stimulated by food, betazole, pentagastrin, caffeine, insulin and physiological vagal reflex. It also reduces peptsin output.
Tenomet® us readily absorbed from the gastro-intestinal tract and peak plasma concentrations are obtained about an hour after administration on an empty stomach and about 2 hours after administration with food. The elimination half-life from plasma of Tenomet® is about 2,5 hours. Tenomet® is weakly bound to plasma proteins and is partially metabolized in the liver, but most is excreted unchanged in the urine. Tenomet® crosses the placental barrier and his excreted into breast milk where concentrations are reported to be higher than those in plasma. It does not readily cross the blood-brain barrier.
Indications
Tenomet® is indicated in the treatment of duodenal and benign gastric ulceration, including that associated with non-steroidal anti-inflammatory agents, recurrent and stomal ulceration, oesophageal reflux and other conditions where reduction of gastric acid by Tenomet® has been shown to be beneficial. Persistent dyspeptic symptoms with or without ulceration, particularly meal-related upper abdominal pain, including such symptoms associated with non-steroidal anti-inflammatory agents; the prophylaxis of gastro-intestinal haemorrhage as a consequence of stress ulceration; before general anaesthesia in patients at risk of acid aspiration (Mendelson’s Syndrome), particularly obstetric patients during labour; to reduce malabsorption and fluid loss in patients with the short bowel syndrome and to reduce the degradation of enzyme supplements given to patients with pancreatic insufficiency. Tenomet® is also recommended in the management of the Zollinger-Ellison syndrom.
Dosage
The total daily dose of Tenomet® should not normally exceed 2,4g. The dosage of Tenomet® should be reduced in patients with impaired renal function. Day time Tenomet® doses should generally be taken with meals. The usual dose by mouth is 400mg twice daily (in the morning and at bedtime); other regiments are 200mg, or if necessary 400mg, three times daily with 400mg at bedtime.
In the management of duodenal and benign gastric ulceration a single daily dose of 800mg by mouth at bedtime is recommended which should be given initially for at least 4 weeks in the case of duodenal and for at least 6 weeks in the case of benign gastric ulcers. Where appropriate a maintenance dose of 400mg may then be given at once at bedtime, or both in the morning and at bedtime.
In the management of duodenal and benign gastric ulceration a single daily dose of 800mg by mouth at bedtime is recommended which should be given initially for at least 4 weeks in the case of duodenal and for at least 6 weeks in the case of benign gastric ulcers. Where appropriate a maintenance dose of 400mg may then be given once at bedtime, or both in the morning and at bedtime.
In reflux oesophagitis the recommended dose is 400mg four times daily (with meals and at bedtime) for 4-8 weeks, and in pathological hypersecretory conditions such as the Zollinger-Ellison syndrome, a dose of 400mg four times daily may also be required, occasionally increased to atatal of 2,4 daily
In the prophylaxis of haemorrhage from stress ulceration in seriously ill patients, doses of 200-400mg ca be given every four to six hours.
In patients thought to be at risk of acid aspiration syndrome an oral dose of 400mg can be given 90-120 minutes before induction of general anaesthesia or, in obstetric practice, at the start of labour.
In the short bowel syndrome, e.g. following substantial resection for Crohn’s disease, the usual dose range can be used according to individual response.
To reduce the degradation of pancreatic enzyme supplements, patients with pancreatic insufficiency may be given Tenomet® 0,8 to 1,6g daily by mouth in four divided doses before meals.
A suggested dose of Tenomet® in children over one year of age is 25 to 30mg per kg body weight daily.
Side Effects
Side-effects to Tenomet® are generally infrequenct and are usually reversible following a reduction of dosage or withdrawal of therapy. The most common side-effects reported have been diarrhoea, dizinnes tiredness and rashes.
Reversible confusional states, especially in the elderly or in seriously ill patients such as whose with renal failure, have occasionally occurred. Tenomet® has a weak anti-androgenic effect and gynaecomastia and impotence have also occasionally occurred in men receiving relatively high doses.
Other side-effects which have been reported rarely are allergic reactions, arthralgia and myalgia, blood disordes, including agranulocytosis or granulocytopenia and thrombocytopenia, interstitial nephritis, headache, hepatotoxicity and pancreatitis.