I. 2 Background
The quality of pharmaceutical products has been a major
concern in many WHO forums. The existence of counterfeit and substandard drug
preparations, which are of unacceptable quality, incited many studies about the
quality of pharmaceuticals available in different countries. The quality of the
pharmaceuticals in the market depends much on the manufacturer and purchaser's
integrity. Through several studies done, it has been shown that the regular
surveillance on the quality and bioavailability of the formulations marketed in
a country is very important.
Even in developed countries where the pharmaceutical market is
highly controlled and strictly regulated, it was possible to find substandard
drugs in the market:
- The National Medicine Control Laboratory of
Finland reported on the quality and bioequivalency of different brands of
erythromycin tablets: the bioavailability of one brand being very low (Venho et
al., 1987). In the same laboratory Eranko et al. (1990) noticed differences in
bioavailability between different brands of nifedipine tablets. In all
occasions the low availability brand had to be withdrawn from the market.
- In studies done in Canada involving 229
generic brands, 9% were identified to be of an unacceptable standard (Maddock,
1986).
In developing countries, Rwanda included, the control and
regulation of pharmaceuticals is not very strict and there have been many
reports of substandard as well as fake drugs on the market:
- Studies done in Nigeria to evaluate the quality of quinine
tablets reported the presence of fake formulations (Sowumni et al., 1994).
- A report on the quality of pharmaceuticals in developing
countries was made by Shakoor et al. (1997) on 81 drugs sampled from Nigeria
and 15 from Thailand, antimalarials and antibiotics commonly used in these
countries. They analyzed by HPLC the content of the active ingredient as well
as the presence of impurities and degradation products. The results showed that
36% (25) of the samples from Nigeria and 40% (6) from Thailand did not comply
with pharmacopoeia standards and 3 of the substandard samples from Nigeria (2
chloroquine and 1 amoxicillin) and 3 from Thailand (chloroquine) were fake.
Through these observations the authors concluded that the major reason for
substandard drugs in the developing countries was poor manufacturing
practice.
- Sulfamethoxazole, an active pharmaceutical ingredient
manufactured in India, was found to be of poor quality and rejected, but was
deliberately being placed at the bottom of every fourth drum ready to be
exported abroad (WHO, 1997).
- Recently, in the Laboratory of Pharmaceutical Technology of
Ghent University, a study on the quality of essential drugs available on the
Tanzanian market was done by Risha et al. (2002). They evaluated the in vitro
availability and its stability under simulated tropical conditions of 22
formulations containing paracetamol, acetylsalicylic acid, chloroquine and
sulfadoxine/pyrimethamine. They used methods specified in the USP 24 monographs
of the respective drugs. All drugs analyzed passed the pharmacopoeia
requirements for the drug content. However seven formulations failed to meet
the USP 24 tolerance limits for dissolution. In addition five formulations
failed to meet the USP 24 tolerance limits for dissolution after being
subjected for six months to an accelated stability test under simulated
tropical conditions (75 % RH, 40 °C). They concluded that the dissolution
behaviour of 12 of the samples was not satisfactory.
They recommended the validation of the manufacturing process
and the use of excipients with predetermined properties.
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