Pioglitazone and Glimepiride

Uses

Glimepiride is used for an adjunct to diet to lower the blood glucose in patients with non-insulin-dependent diabetes mellitus (type 2 diabetes) whose hyperglycemia cannot be controlled by diet, physical exercise and weight reduction.

Glimepiride is also used for use in combination with Insulin to lower blood glucose in patients whose hyperglycaemia can not be controlled by diet and exercise or in conjunction with an oral hypoglycaemic agent.

Pioglitazone and Glimepiride is also used to associated treatment for these conditions: Type 2 Diabetes Mellitus

How Pioglitazone and Glimepiride works

ATP-sensitive potassium channels on pancreatic beta cells that are gated by intracellular ATP and ADP. The hetero-octomeric complex of the channel is composed of four pore-forming Kir6.2 subunits and four regulatory sulfonylurea receptor (SUR) subunits. Alternative splicing allows the formation of channels composed of varying subunit isoforms expressed at different concentrations in different tissues. In pancreatic beta cells, ATP-sensitive potassium channels play a role as essential metabolic sensors and regulators that couple membrane excitability with glucose-stimulated insulin secretion (GSIS). When there is a decrease in the ATP:ADP ratio, the channels are activated and open, leading to K+ efflux from the cell, membrane hyperpolarization, and suppression of insulin secretion. In contrast, increased uptake of glucose into the cell leads to elevated intracellular ATP:ADP ratio, leading to the closure of channels and membrane depolarization. Depolarization leads to activation and opening of the voltage-dependent Ca2+ channels and consequently an influx of calcium ions into the cell. Elevated intracellular calcium levels causes the contraction of the filaments of actomyosin responsible for the exocytosis of insulin granules stored in vesicles. Glimepiride blocks the ATP-sensitive potassium channel by binding non-specifically to the B sites of both sulfonylurea receptor-1 (SUR1) and sulfonylurea receptor-2A (SUR2A) subunits as well as the A site of SUR1 subunit of the channel to promote insulin secretion from the beta cell.

Dosage

Pioglitazone and Glimepiride dosage

In principle, the dosage of Glimepiride is governed by the desired blood sugar level. The dosage of Glimepiride must be the lowest which is sufficient to achieve the desired metabolic control.

The initial and the maintenance doses are set based on the results of regular checking of glucose in blood and urine. Monitoring of glucose levels in blood and urine also serves to detect either primary or secondary failure of therapy.

Initial dose and dose titration: Usual initial dose is 1 mg once daily. If necessary, the daily dose can be increased. Any increase can be based on regular blood sugar monitoring, and should be gradual, i.e., at intervals of one to two weeks and carried out step wise at follows: 1 mg-2 mg-3 mg-4 mg-6 mg.

Dose range in patients with well controlled diabetes: Usual dose range in patients with well controlled diabetes is 1 to 4 mg daily.

Distribution of doses: Timing and distribution of doses are decided by the physician, in consideration of the patient's current life style. Normally, a single daily dose is sufficient. This should be taken immediately before a substantial breakfast or - if none is taken - immediately before the first main meals. It is very important not to skip meals after taking the drug.

Secondary dosage adjustment: As the control of diabetes improves, sensitivity to insulin increases; therefore, Glimepiride requirement may fall as treatment proceeds. To avoid hypoglycaemia, timely dose reduction or cessation of Glimepiride therapy must be considered.A dose adjustment must also be considered whenever the patient's weight or life style changes, or other factors arise which cause an increased susceptibility to hypo- or hyperglycaemia.

Changeover from other oral antidiabetics to Glimepiride: There is no exact dosage relationship between Glimepiride and other oral blood sugar lowering agents. When substituting Glimepride for other such agents, the initial daily dose is 1 mg; this applies even in changeover from the maximum dose of other oral blood sugar lowering agents. Any dose increase should be in accordance with guideline given above in initial dose and dose titration.

Consideration must be given to the potency and duration of action of the previous blood sugar lowering agent. It may be necessary to interrupt treatment to avoid additive effects which would increase the risk of hypoglycaemia.

Diaryl tablet must be swallowed without chewing and with sufficient amount of liquid (approximately ½ glass).

Side Effects

Hypoglycaemia, temporary visual impairment, nausea, vomiting, diarrhoea, abdominal pain, urticaria & fall in blood pressure.

Toxicity

The oral LD50 value in rats is > 10000 mg/kg. The intraperitoneal LD50 value in rats is reported to be 3950 mg/kg . Although glimepiride is reported to have fewer risks of hypoglycemia compared to other sulfonylureas such as glyburide, overdosage of glimepiride may result in severe hypoglycemia with coma, seizure, or other neurological impairment may occur. This can be treated with glucagon or intravenous glucose. Continued observation and additional carbohydrate intake may be necessary since hypoglycemia may recur after apparent clinical recovery.

In a study of rats given doses of up to 5000 parts per million (ppm) in complete feed for 30 months, there were no signs of carcinogenesis. Meanwhile, the administration of glimepiride at a dose much higher than the maximum human recommended dose for 24 months in mice resulted in an increase in benign pancreatic adenoma formation in a dose-related manner, which was thought to be the result of chronic pancreatic stimulation. Glimepiride was non-mutagenic in in vitro and in vivo mutagenicity studies. In male and female rat studies, glimepiride was shown to have no effects on fertility.

Precaution

In the initial weeks of treatment, the risk of hypoglycaemia may be increased and necessitates careful monitoring. If such risk is present it may be necessary to adjust the dosage of Glimepiride. Hypoglycaemia can almost always be promptly controlled by immediate intake of carbohydrates (glucose or sugar, e.g., sugar sweetened fruit juice or sugar sweetened tea)

Interaction

Potentiation of the blood-sugar-lowering effect may occur with Insulin and other oral anti-diabetics, ACE inhibitors, Allopurinol, anabolic steroids and male sex hormones, Chloramphenicol, coumarin derivatives, Fluoxetine, MAO inhibitors, Miconazole, Para-aminosalicyclic acid, Pentoxifylline (high dose parenteral), Phenylbutazone, Oxyphenbutazone, quinolones, salicylates, sulphonamides, tetracyclines, β blockers.

Weakening of the blood-sugar-lowering effect may occur with Acetazolamide, barbiturates, corticosteroids, Diazoxide, diuretics, Epinephrine and other sympathomimetic agents, laxative, oestrogens and progestogens, phenothiazines, Phenytoin, Rifampicin, and thyroid hormones.

H2 -receptor antagonists, Clonidine and Reserpine may lead to either potentiation or weakening of the blood-sugar-lowering effect.

Both acute and chronic alcohol intake may potentiate or weaken the blood-sugar-lowering action of Glimepiride unpredictably.

Volume of Distribution

Following intravenous dosing in healthy subjects, the volume of distribution was 8.8 L (113 mL/kg).

Elimination Route

Glimepiride is completely absorbed after oral administration within 1 hour of administration with a linear pharmacokinetics profile. Following administration of a single oral dose of glimepiride in healthy subjects and with multiple oral doses with type 2 diabetes, the peak plasma concentrations (Cmax) were reached after 2 to 3 hours post-dose. Accumulation does not occur after multiple doses. When glimepiride was given with meals, the time to reach Cmax was increased by 12% while the mean and AUC (area under the curve) were decreased by 8 to 9%, respectively. In a pharmacokinetic study of Japanese patients with T2DM, Cmax value in once-daily dose was higher than those in twice-daily doses. The absolute bioavailability of glimepiride is reported to be complete following oral administration.

Half Life

The elimination half-life of glimepiride is approximately 5 to 8 hours, which can increase up to 9 hours following multiple doses.

Clearance

A single-dose, crossover, dose-proportionality (1, 2, 4, and 8 mg) study in normal subjects and from a single- and multiple-dose, parallel, dose proportionality (4 and 8 mg) study in patients with type 2 diabetes (T2D) were performed. In these studies, the total body clearance was 52.1 +/- 16.0 mL/min, 48.5 +/- 29.3 mL/min in patients with T2D given a single oral dose, and 52.7 +/- 40.3 mL/min in patients with T2D given multiple oral doses. Following intravenous dosing in healthy subjects, the total body clearance was 47.8 mL/min.

Elimination Route

Following oral administration of glimepiride in healthy male subjects, approximately 60% of the total radioactivity was recovered in the urine in 7 days, with M1 and M2 accounting for 80-90% of the total radioactivity recovered in the urine. The ratio of M1 to M2 was approximately 3:2 in two subjects and 4:1 in one subject. Approximately 40% of the total radioactivity was recovered in feces where M1 and M2 accounted for about 70% of the radioactivity and a ratio of M1 to M2 being 1:3. No parent drug was recovered from urine or feces.

Pregnancy & Breastfeeding use

Pregnancy: Glimepiride must not be taken during pregnancy; a changeover to Insulin is necessary. Patients planning a pregnancy must inform their physician, and should be shifted to Insulin.

Lactation: Ingestion of Glimepiride with breast milk may harm the child. Therefore, Glimepiride must not be taken by lactating women. Either a changeover or a complete discontinuation of breast-feeding is necessary.

Contraindication

Glimepiride is not suitable for the treatment of insulin dependent (type-I) diabetes mellitus, or of diabetic pre-coma or coma. Glimepiride must not be used in patients hypersensitive to Glimepiride or other sulphonylureas.

Special Warning

Pediatric use: Safety and effectiveness in pediatric patients have not been established.

Geriatric use: No overall differences in safety or effectiveness were observed between elderly and adult subjects, but greater sensitivity of some older individuals cannot be ruled out. The drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function.

Use in renal insufficiency: A starting dose of 1 mg glimepiride may be given to NIDDM patients with kidney disease, and the dose may be titrated based on fasting blood glucose levels.

Use in hepatic insufficiency: No studies were performed in patients with hepatic insufficiency. Adverse reactions: Hypoglycemia. Adverse events, other than hypoglycemia, are dizzines, asthenia, headache, and nausea.

Acute Overdose

Accidental or intentional overdose may cause severe and prolonged hypoglycemia which may be life-threatening. In case of overdosage with Glimepiride, a doctor must be notified immediately. At the first signs of hypoglycemia, the patient must immediately take sugar, preferably glucose, unless a doctor has already started care.

Storage Condition

Store at 25° C.

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