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)

StudyCountryActive pharmaceutical ingredientTotal no of samples collectedFailed samples
n (%)
Prevalence surveys
Blume et al85Argentina, 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, USAGlibenclamide1878 (4.3)
Westenberger et al40UnstatedMetformin40 (0.0)
Central Drugs Standard Control Organisation86IndiaMetformin, gliclazide, glimepiride450 (0.0)
Ebenezer87NigeriaMetformin1797 (3.9)
Islam39CambodiaMetformin, glibenclamide11221 (18.8)*
Equivalence studies
Attorrese and Massi-Benedetti70UnstatedGlimepiride2312 (52.2)
Hamdan and Jaber88JordanMetformin51 (20.0)
Chandrasekaran et al89MalaysiaMetformin50 (0.0)
 Afifi and Ahmadeen90Saudi ArabiaMetformin60 (0.0)
Chatur et al91UnstatedVoglibose51 (20.0)
Olusola et al92NigeriaMetformin81 (12.5)
Oyetunde et al93NigeriaMetformin52 (40.0)
El-Sabawi et al94JordanGlibenclamide63 (50.0)
Labu et al95BangladeshMetformin70 (0.0)
Ajala et al96NigeriaMetformin83 (37.5)
Betari and Haidar97UnstatedSitagliptin52 (40.0)
Elango and Shanmuganathan98IndiaMetformin153 (20.0)
Elhamili et al99LibyaGlibenclamide30 (0.0)
Abdulhameed et al100IraqMetformin50 (0.0)
Gupta et al101Trinidad and TobagoMetformin40 (0.0)
Sachan et al102IndiaMetformin40 (0.0)
Sakr et al103Saudi ArabiaGlibenclamide80 (0.0)
Alam et al104Saudi ArabiaGlibenclamide50 (0.0)
Eraga et al105NigeriaMetformin108 (80.0)†
Aivalli et al106IndiaMetformin, glibenclamide100 (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.