I am glad to read you are having good results with the Retin A/Clindamycin combo, probably either Ziana or Veltin.
Clindamycin is an antibiotic in the Lincosamide family. It works by interfering with the production of proteins by the ribosomes of the bacteria. Since our ribosomes are structured differently, we are able to tolerate Clindamycin.
A drug called Lincomycin was the predecessor of Clindamycin, but Clindo, as it is affectionately called by us physicians, was found to be superior in killing bacteria, and thus has super-ceded Lincomycin.
As far as acne treatment, Clindamycin has really become the topical antibiotic of choice and is by far, the most frequently used. The first topical antibiotic was Topicycline. This, curiously, was made by Proctor & Gamble, a company far better known for producing Crest toothpaste, Tide detergent, Bounty and now Gillette razor blades. Not only was it a decent product to treat acne, it was a hit in discos all across the country since it turned the faces of its users a colorful green-yellow color once the ever popular strobe lights of that era were turned on. However, it faded in popularity once topical erythromycin was introduced. The bacteria figured out how to resist topical ( and oral) erythromycin, so the pharmaceutical makers developed topical forms of Clindamycin.
Upjohn was the first company to introduce Cleocin T and put it into various delivery systems including solution, pads, creams and gels. Later, it was found that adding Benzoyl Peroxide prevented bacterial resistance and BenzaClin was born. This was followed by two "me-too" drugs Duac and later Acanya, the former two using 5% BP, and the later 2%.( Incidentally, bacteria do not seem to develop resistance to Benzoyl Peroxide since they are basically smothered by it. You have heard of anti-oxidants right? Well, BP is the supreme oxidant. It aggressively grabs electrons and puts the air into an oxidative state. It produces so much oxygen that the bacteria, which like oxygen in small amounts, are overwhelmed and essentially smothered. )
Later, Clindamycin was placed into Ziana and Veltin. This combines Retin A and Clindamycin. Its makers boast that Retin A opens up the skin and allows Clindamycin better penetration. An additional advantage is that Clindamycin is a pretty strong anti-inflammatory agent. This helps control some of the inflammation concomitant with the use of Retin A. Clindamycin does make the skin more tolerant of Retin A.
There are some other interesting facts about Clindamycin. A recent study showed that it may be the drug of choice for MRSA ( methacillin resistant staph aureus). Although physicians still mostly prescribe Doxycycline and Bactrim for this, this study showed that Clindamycin is actually the most effective. One problem, though, is that as monotherapy ( only using Clindamycin and not a combination therapy) resistance can develop. Another reason for physician reluctance to use oral Clindamycin is the possible development of Clostridium Difficile. This is due to the effectiveness of Clindamycin at killing off bacteria, even the "good bacteria" of the gut, allowing C Diff ( as we NOT affectionately refer to it!) to proliferate. C. Diff is actually a cousin of Clostridium Botolinum, which has enjoyed a degree of fame by warping from a biologic agent of death to a killer of wrinkles.
Physicians have to watch out for excessive use of topical Clindamycin. I have a patient with a rare disease called Hailey-Hailey who I was treating with TOPICAL Clindamycin into her armpits and groin. When she developed diarrhea, a culture was done and grew out the infamous, C. Difficile. She was treated with the old Gynecology stand-by Flagyl ( used for decades to treat Trichomonas, not so affectionately referred to as Trick) and did fine. Still, that is a cautionary tale.
Clindamycin is also especially effective for toxic shock syndrome and malaria.