Miglitol dosing

Acarbose (Precose) and miglitol (Glyset) are dosed similarly. Therapy is initiated with a very low dose (25 mg with one meal a day) and increased very gradually (over several months) to a maximum of 50 mg three times daily for patients weighing 60 kg or more, or 100 mg three times daily for patients above 60 kg. The drugs should be taken with the first bite of the meal so that the drug is present to inhibit enzyme activity. 

In contrast to sulfonylureas and thiazolidinediones, miglitol does not enhance insulin secretion. Miglitol has minor inhibitory activity against lactase and, at recommended doses, would not be expected to induce lactose intolerance. 

Absorption - Absorption of miglitol is saturable at high doses a dose of 25 mg is completely absorbed, whereas a dose of 100 mg is only 50% to 70% absorbed. Peak concentrations are reached in 2 to 3 hours. 

Excretion - Miglitol is eliminated by renal excretion as unchanged drug. Following a 25 mg dose, more than 95% of the dose is recovered in the urine within 24 hours. The elimination half-life from plasma is approximately 2 hours. 

In 33 patients with type 2 diabetes treated with sulfo-nylureas and insulin who took miglitol 50 mg bd for 1 week and then over the next month increased the dose to 50 mg tds, 15% developed adverse effects (6% diarrhea, 6% abdominal distension), which disappeared within 3 weeks of continuing therapy (42). 

Acarhose or Miglitol and Food. Some medications should be administered with food for optimum benefit. Acarbose (Precose) and miglitol (Glyset) are effective in the treatment of diabetes mellitus because they delay the digestion of ingested carbohydrates and reduce the elevation of blood glucose concentrations following meals. Maximum effectiveness is attained when doses are administered at the start (with the first bite) of each main meal. 

Low doses (25 mg) of miglitol are completely absorbed, but absorption is saturable and is incomplete at higher doses. Peak plasma concentrations occur in 2-3 h. The volume of distribution, 0.18 L/kg, is consistent with distribution primarily into extracellular water and binding to plasma proteins is negligible. Miglitol is renally excreted as unchanged drug, with a plasma elimination half-life of 2 h. 

In a double-blind, randomised, placebo-controlled study, 24 healthy subjects were given miglitol 100 mg three times daily for 7 days, with a single 25-mg oral dose of warfarin on day 4. Neither the pharmacokinetics nor the pharmacodynamics ofR- or 5-warfarin was affected by the miglitol No special precautions would therefore appear to be needed if these two drugs are used concurrently. 

Another study in 19 diabetic patients given acarbose 50 or 100 mg three times daily and metformin 500 mg twice daily, also found that acarbose lowered metformin levels (AUC reduced by 12 to 13%, maximum plasma levels reduced by 17 to 20%). Nevertheless, the drug combination reduced the postprandial glucose concentration at 3 hours by 15% mote than metformin alone. Similarly, the manufacturer notes that, in a study in healthy subjects, miglitol 100 mg three times daily for 7 days reduced the AUC and maximum level of a single 1-g dose of metformin by 12% and 13%, respectively, although this difference was not statistically significant. ... 

Pharmacokinetic studies. Acarbose 300 mg daily for one week had no effect on the pharmacokinetics or pharmacodynamics of a single 80-mg dose of propranolol in healthy subjects. Conversely, the manufacturer of miglitol notes that it reduced the bioavailability of propranolol by a... 

Large and toxic doses of phenytoin have been observed to cause hyperglycaemia, but normal therapeutic doses do not usually affect the control of diabetes. Two isolated cases of phenytoin toxicity have been attributed to the use of tolazamide or tolbutamide. Miglitol does not affect the bioavailability of phenytoin. 

Tolbutamide 500 mg two or three times daily was given to 17 patients taking phenytoin 100 to 400 mg daily. The patients had a transient 45% rise in the amount of non-protein-bound phenytoin by day 2, which had disappeared by day 4. The introduction to this report briefly mentions a man given phenytoin and tolazamide who developed phenytoin toxicity, which disappeared when the tolazamide was replaced by insulin. A woman previously uneventfully treated with phenytoin and tolbutamide developed toxicity on a later occasion when she took tolbutamide with twice the previous dose of phenytoin. One study in healthy subjects found that miglitol 100 mg three times daily for 5 days did not affect the bioavailability of a single 400-mg dose of phenytoin. ... 

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