The right common carotid artery arises from the brachiocephalic trunk (posterior to the right sternoclavicular joint), whereas the left common carotid is a branch of the arch of the aorta and hence has a thoracic portion before it reaches the neck (posterior to the left sternoclavicular joint).
Metformin Dosing. The recommended starting dosage of metformin is  500 mg twice daily. The maximum dosage for children age 10 to 16 is 2000 mg, and for adults age 17 and older is 2550 mg. Your dose should be increased only when necessary and should be increased slowly in order to avoid side effects.
Metformin Dosing and Protocol. Metformin is taken in a dose that the woman can tolerate. Most people can tolerate 500 mg three times daily, if they build up to that dose gradually. 1  We start metformin at 500 mg once daily, increase to 500 mg twice a day after one week, then to 500 mg 3 times daily after another week. We start metformin at 500 mg once daily, increase to 500 mg twice a day after one week, then to 500 mg 3 times daily after another week.