Consumer medicine information

1. Why am I using Metformin GH?

Metformin GH contains the active ingredient metformin hydrochloride. Metformin GH is used to control blood glucose (the amount of sugar in the blood) in people with diabetes mellitus.
For more information, see Section 1. Why am I using Metformin GH? in the full CMI.

2. What should I know before I use Metformin GH?

Do not use if you have ever had an allergic reaction to metformin hydrochloride or any of the ingredients listed at the end of the CMI.
Talk to your doctor or pharmacist if you have any other medical conditions, take any other medicines, or are pregnant or plan to become pregnant or are breastfeeding.
For more information, see Section 2. What should I know before I use Metformin GH? in the full CMI.

3. What if I am taking other medicines?

Some medicines may interfere with Metformin GH and affect how it works.
A list of these medicines is in Section 3. What if I am taking other medicines? in the full CMI.

4. How do I use Metformin GH?

• The dose varies from person to person.

• The usual starting dose for adults is 500 mg one to two times a day. Your doctor may increase or decrease the dose, depending on your blood glucose levels. More instructions can be found in Section 4. How do I use Metformin GH? in the full CMI.

5. What should I know while using Metformin GH?

6. Are there any side effects?

Tell your doctor or pharmacist if you notice any of the following and they worry you: nausea, vomiting, diarrhoea, stomach pain, taste disturbance, loss of appetite, skin reactions such as redness of the skin or itching. Tell your doctor immediately or go to Accident and Emergency at the nearest hospital if you notice any of the following symptoms: trouble breathing, feeling weak, tired or generally unwell, unusual muscle pain, sleepiness, dizziness, shivering, feeling extremely cold or slow heart beat. For more information, including what to do if you have any side effects, see Section 6. Are there any side effects? in the full CMI.

Boxed Warnings

Life threatening lactic acidosis can occur due to accumulation of metformin. Risk factors include renal impairment, old age and the use of high doses of metformin above 2 g per day.

1 Name of Medicine

Metformin hydrochloride.

2 Qualitative and Quantitative Composition

Each Metformin GH 500 mg tablet contains 500 mg of metformin hydrochloride. Each Metformin GH 850 mg tablet contains 850 mg of metformin hydrochloride. Each Metformin GH 1000 mg tablet contains 1000 mg of metformin hydrochloride.
For the full list of excipients, see Section 6.1 List of Excipients.

3 Pharmaceutical Form

Metformin GH 500 mg. White, film-coated, round, biconvex tablets debossed with "500" on one side and plain on the other side.
Metformin GH 850 mg. White, film-coated, round, biconvex tablets debossed with "850" on one side and plain on the other side.
Metformin GH 1000 mg. White to off-white, film-coated, oval shaped, biconvex tablets debossed with '10' and '00' on either side of deep notch on one side and breakline on other side.

4 Clinical Particulars

4.9 Overdose

Symptoms. Hypoglycaemia has not been seen with ingestion of up to 85 g of metformin alone, although lactic acidosis has occurred in such circumstances. This disorder is a medical emergency and must be treated in hospital. The onset of lactic acidosis is often subtle and accompanied only by non-specific symptoms such as malaise, myalgia, respiratory distress, increasing somnolence and non-specific abdominal distress. There may be associated hypothermia, hypotension and resistant bradyarrhythmias with more marked acidosis. Lactic acidosis should be suspected in any diabetic patient with metabolic acidosis lacking evidence of ketoacidosis (ketonuria and ketonaemia).
Treatment. Lactic acidosis may develop in diabetic metformin-treated patients with overdose. Lactic acidosis is diagnosed and monitored by measurement of serum electrolytes, arterial pH and pCO₂ and arterial lactate plasma level.
The aim of treatment is to manage any underlying disorder and in some cases, this will be sufficient to enable the body's homeostatic mechanism to correct the acid-base imbalance. The advantages of more active treatment of the acidosis must be balanced against the risks, including over-alkalinisation with sodium bicarbonate. Because metformin hydrochloride is dialysable (with a clearance of up to 170 mL/min under good haemodynamic conditions), prompt haemodialysis is recommended to correct the acidosis and remove the accumulated metformin.
For information on the management of overdose, contact the Poisons Information Centre on 13 11 26 (Australia).

5 Pharmacological Properties

5.3 Preclinical Safety Data

Genotoxicity. No evidence of a mutagenic potential of metformin was found in the Ames test (S. typhimurium), gene mutation test (mouse lymphoma cells), chromosomal aberrations test (human lymphocytes), or in vivo micronuclei formation test (mouse bone marrow).
Carcinogenicity. Long term carcinogenicity studies have been performed in rats (dosing duration of 104 weeks) and mice (dosing duration of 91 weeks) at doses up to and including 900 mg/kg/day and 1500 mg/kg/day, respectively. These doses are both approximately two to three times the recommended human daily dose on a body surface area basis. No evidence of carcinogenicity with metformin was found in either male or female mice. Similarly, there was no tumourigenic potential observed with metformin in male rats. However, an increased incidence of benign stromal uterine polyps was seen in female rats treated with 900 mg/kg/day.

6 Pharmaceutical Particulars

6.7 Physicochemical Properties

Metformin hydrochloride is a white, crystalline powder which is odourless or almost odourless and hygroscopic. It is freely soluble in water, slightly soluble in ethanol (96%), and practically insoluble in chloroform and in ether.
Chemical structure.
https://stagingapi.mims.com/au/public/v2/images/fullchemgif/CSMETFOH.gif Chemical Name: 1,1-dimethylbiguanide hydrochloride.
Molecular Formula: C₄H₁₁N₅,HCl.
Molecular Weight: 165.62.
CAS number. 1115-70-4.

7 Medicine Schedule (Poisons Standard)

S4 - Prescription Only Medicine.

Summary Table of Changes

https://stagingapi.mims.com/au/public/v2/images/fulltablegif/METFGHST.gif