When choosing injectable penicillin for the treatment of group A beta-hemolytic streptococcal pharyngitis, there is a less painful choice

Objective To determine whether injection of patients with Bicillin CR is less painful than injection with Bicillin LA. To discover if Bicillin CR with the addition of procaine, which doubles the volume, causes the injection to be less painful. Design: An experimental, double-blinded crossover design was used for this study. Setting: University children's and women's tertiary care emergency Department (ED) with an annual pediatric census of 22,000, Participants: A convenience sample was enrolled from the student body of a large university and house staff, and employees of a 152 bed children's and women's hospital in southern Alabama. The sample size was limited to 50 participants, all of whom completed the study. Methods: Each participant received two penicillin injections, one Bicillin CR and one Bicillin LA, and rated the pain of the injection immediately after the injection, 1 hour after the injection and 12 hours after the injection. A visual analogue scale was the tool used for measuring the pain. The penicillin injections were randomized using a random number generator. Results: For each of the three periods, comparisons of pain were made:between the Bicillin CR versus Bicillin LA injections. Bicillin LA pain score values were consistently higher for all but the 12-hour comparison. These differences were statistically;significant (P < 0.008-0.002), Conclusions: Injection of Bicillin CR with the addition of procaine to the benzathine penicillin G is statistically significantly less painful than the injection of Bicillin LA without the addition of procaine to the benzathine penicillin G, even though the Bicillin LA is one-half the volume of the Bicillin CR due to the addition of procaine to the Bicillin CR.