01Is the 500 mg tablet a different drug from the 850?
Both tablets are metformin hydrochloride. 500 mg is 389.93 mg of metformin base. 850 mg is 662.88 mg of base. 1000 mg is 779.86 mg of base. Those base numbers sit on the description section of the US tablet label. The molecular weight of metformin hydrochloride is 165.63.
The clinician picks a strength so the daily total can be built from whole tablets. A 500 mg tablet is the usual first piece because the labelled start is 500 mg twice daily or 500 mg once daily. Cutting a 1000 mg tablet to make 500 mg is a pharmacy-and-clinician question, not a home invent.
02Does generic metformin start the same way as Glucophage?
Adult immediate-release metformin starts at 500 mg twice daily or 850 mg once daily, given with meals. Some charts open at 500 mg once daily and add the second swallow after the gut settles. The weekly 500 mg step, or an 850 mg step every two weeks, is the labelled climb. Generic metformin uses that same table.
The ceiling on that immediate-release line is often 2550 mg a day in divided doses. Totals above 2000 mg may sit better as three meals rather than two. Generic and brand share that schedule. A child's labelled cap on Glucophage is 2000 mg a day, not 2550 mg.
03Why do most US fills now name metformin, not Glucophage?
Pharmacies have filled metformin as the generic for years. The brand Glucophage name still appears on the US prescribing information. The bottle that leaves the counter usually says metformin hydrochloride. Glucophage's initial US approval year is 1995. This page does not invent an ANDA date for the generic. The 500 mg, 850 mg, and 1000 mg tablet line is the same on brand and generic.
A clinician can still write Glucophage. Substitution then follows that state's pharmacy rules and whatever the slip allowed. The how-to-get page is who writes that slip. Brand and generic both need that written order.
04Can the pharmacy swap brand for generic on the same order?
If the slip names Glucophage and the state allows substitution, the fill is often generic metformin at the same milligram strength. If the slip says dispense as written, the brand line stays. The milligrams on that line are still 500, 850, or 1000. A generic 500 mg tablet still starts with meals.
The person at the window can ask which name left the computer. The swallow, the meals, and the kidney stops do not change with the name on the cap. A 500 mg generic tablet is still the 500 mg start this shelf talks about.
05Does a generic bottle still carry the lactic acidosis warning?
Yes. The boxed warning travels with metformin. Postmarketing lactic acidosis cases have included death, hypothermia, hypotension, and resistant bradyarrhythmias. Onset can look like malaise, muscle ache, trouble breathing, sleepiness, or belly pain. Risk rises with marked renal impairment, hypoxic states, and excessive alcohol. Age 65 or older and hepatic impairment sit on that same list.
A generic cap does not drop that warning. eGFR below 30 still contraindicates the tablet. Starting between 30 and 45 is still not recommended. If lactic acidosis is suspected, the tablet stops and care moves to a hospital. Hemodialysis is the labelled clearance step.
06What tablet strengths sit on a generic metformin bottle?
A US immediate-release metformin bottle can hold 500 mg, 850 mg, or 1000 mg tablets. Those are the same three Glucophage tablet strengths. The pharmacy labels the milligrams that arrived on the order, not a fourth invented size. A 750 mg or 1500 mg IR tablet is not on that US list.
This site talks about the 500 mg tablet. The 850 mg and 1000 mg lines still exist on the US label. They are later steps on the same climb, not a different drug. An extended-release bottle is a different once-daily schedule. See the metformin shelf for the 500 mg IR opening.