Table 1.
Main characteristics of prevalence surveys and equivalence studies of antidiabetic medicines included in the reviewBecause of the limited number of samples tested for quality in the studies included in this review, the numbers should not be interpreted as representative of the prevalence of specific SF antidiabetics (please refer to the discussion section of the current paper for more details)
| Study | Country | Active pharmaceutical ingredient | Total no of samples collected | Failed samples n (%) |
| Prevalence surveys | ||||
| Blume et al85 | Argentina, Australia, Austria, Belgium, Canada, Chile, Commonwealth of Independent States, Denmark, Egypt, Finland, France, Germany, Greece, Hungary, Indonesia, Italy, Japan, Luxembourg, Netherlands, Pakistan, Portugal, Spain, Sweden, Switzerland, Thailand, Turkey, UK, USA | Glibenclamide | 187 | 8 (4.3) |
| Westenberger et al 40 | Unstated | Metformin | 4 | 0 (0.0) |
| Central Drugs Standard Control Organisation86 | India | Metformin, gliclazide, glimepiride | 45 | 0 (0.0) |
| Ebenezer87 | Nigeria | Metformin | 179 | 7 (3.9) |
| Islam39 | Cambodia | Metformin, glibenclamide | 112 | 21 (18.8)* |
| Equivalence studies | ||||
| Attorrese and Massi-Benedetti70 | Unstated | Glimepiride | 23 | 12 (52.2) |
| Hamdan and Jaber88 | Jordan | Metformin | 5 | 1 (20.0) |
| Chandrasekaran et al 89 | Malaysia | Metformin | 5 | 0 (0.0) |
| Afifi and Ahmadeen90 | Saudi Arabia | Metformin | 6 | 0 (0.0) |
| Chatur et al91 | Unstated | Voglibose | 5 | 1 (20.0) |
| Olusola et al 92 | Nigeria | Metformin | 8 | 1 (12.5) |
| Oyetunde et al 93 | Nigeria | Metformin | 5 | 2 (40.0) |
| El-Sabawi et al 94 | Jordan | Glibenclamide | 6 | 3 (50.0) |
| Labu et al 95 | Bangladesh | Metformin | 7 | 0 (0.0) |
| Ajala et al 96 | Nigeria | Metformin | 8 | 3 (37.5) |
| Betari and Haidar97 | Unstated | Sitagliptin | 5 | 2 (40.0) |
| Elango and Shanmuganathan98 | India | Metformin | 15 | 3 (20.0) |
| Elhamili et al 99 | Libya | Glibenclamide | 3 | 0 (0.0) |
| Abdulhameed et al 100 | Iraq | Metformin | 5 | 0 (0.0) |
| Gupta et al 101 | Trinidad and Tobago | Metformin | 4 | 0 (0.0) |
| Sachan et al 102 | India | Metformin | 4 | 0 (0.0) |
| Sakr et al 103 | Saudi Arabia | Glibenclamide | 8 | 0 (0.0) |
| Alam et al 104 | Saudi Arabia | Glibenclamide | 5 | 0 (0.0) |
| Eraga et al 105 | Nigeria | Metformin | 10 | 8 (80.0)† |
| Aivalli et al 106 | India | Metformin, glibenclamide | 10 | 0 (0.0) |
*In Islam 2017,39 only the number of medicine failing each quality test was mentioned. Since one medicine may fail more than one test, the failure rate was recorded as the highest possible number of samples failing one of the tests.
†In Eraga 2017,105 uniformity of content was assessed using two methods that is, UV spectrophotometry and reverse-phase high-performance liquid chromatography. There are several discrepancies in the results of these two tests. Therefore, if samples failed either, they will be categorised as failed samples.
SF, substandard and falsified; UV, ultraviolet.