Metformin structure

Chemical Name Biguanide, 1,1-dimethyl-, hydrochloride Common Name Dimethylguanilguanidini chloridum Metformin Structural Formula ... 

The structure of metformin is shown below. Phenformin (an older biguanide) was discontinued in the USA because of its association with lactic acidosis and because there was no documentation of any long-term benefit from its use. 

The lower frequency of lactic acidosis during treatment with metformin compared with other biguanides may be caused by its short non-polar hydrophobic side chains substituted with two CH3 groups. This has a lower affinity for hydrophobic structures, such as phospholipids in mitochondrial and cellular membranes, than the longer monosubstituted side-chains of the other biguanides (64). 

Metformin treatment of patients with NIDDM led to an improvement in both glycaemic control and lipoprotein metabolism (Wu etal., 1990). Triglycerides are reduced by 40% in patients with hyperlipoproteinaemia. Metformin helps combat hypertriglyceridaemia (Bailey, 1992) and has been ascribed some vasoprotective properties (Bailey, 1992). Metformin prevents experimental atherosclerosis and induces structural changes in lipoproteins in experimental animals. The reduction in total and LDL cholesterol levels was shown for diabetic patients with hypercholesterolaemia (Rains et al., 1989 Pentikainen... 

Figure 5.3 Structures of four antidiabetic drugs. Glucophage (metformin) and Avandia (rosiglitazone) are currently marketed in the US, while phenformin and troglitazone are not due to safety issues.

Fourier transform infrared (FT-IR) spectroscopy can be used to characterize drug substances, polymer blends, polymer complexes, dynamics, surfaces, and interfaces, as well as chromatographic effluents and degradation products. It provides information about the complexation and interactions between the various constituents in the PECs. It is capable of qualitative identification of the structure of unknown materials as well as the quantitative measurement of the components in a complex mixture. FT-IR spectra of physical mixture and PEC can be determined by FT-IR spectrophotometer using KBr disc method in the range of 4000 to 250 cm h Since the stability and drug substance is very important in several applications, determination of their physicochemical stability is crucial. The FTIR spectra of polyacrylic acid, PVP, metformin hydrochloride, and PEC microparticles of metformin were shown in Figure 56.8. The FTIR spectra of polyacrylic acid and PVP have shown... 

FIGURE 56.10 SEM photographs of metformin (a) PEC microparticles and (b) porous surface structure. 

Following is a structural formula for metformin, the hydrochloride salt of which is marketed as the antidiabetic Glucophage (See Example 10.7)... 

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