According to the American College of Cardiology/American Heart Association (ACC/AHA), both aspirin
and statin are used in the primary prevention of cardiovascular diseases. Aspirin (ASA) is contraindicated
if there is gastrointestinal bleeding because it will exaggerate the condition. In this study, the effect of
surfactant; sodium lauryl sulfate (SLS), in enhancing the in vitro dissolution of simvastatin (SIM) and
ASA, as well as gastric irritation and upset, was studied. Oral tablets containing both ASA and SIM with
and without the SLS were manufactured using the direct compression technique. The prepared tablets
were characterized with respect to hardness, friability, uniformity of dosage units, in vitro disintegration,
and dissolution. The effect of the addition of SLS in reducing the in vivo irritation and protection of gastric
mucosa were also investigated. The results showed that the compressed tablets possessed sufficient
hardness, acceptable friability, and are uniform with respect to disintegration, drugs contents, and tablet
weight. The results showed that SIM alone exhibited a gastroprotective effect on the induced irritation. In
addition, the incorporation of the SLS in the tablets containing SIM and ASA significantly enhanced the
dissolution rates of both drugs and significantly decreased the gastric irritation and the ulcer index.
The ulcer index of aspirin was decreased from 2.3 for tablets manufactured without SLS to 0.8 for tablets
containing SLS. In a conclusion, the addition of pH modifier surfactant; SLS could enhance the dissolution
rate of poorly soluble acidic drugs, reduce gastric upset and irritation without any effect on the main
characters of the tablets. Moreover, the addition of SLS is very useful in improving the therapeutic activities
and reducing the side effects of ASA and SIM for patients who require long-term administration of
these drugs.