Doxycycline hyclate (Vibramycin, Periostat, Vibra-Tabs) is salt of tetracycline antibiotic Doxycycline, that used to treat many kinds of infections, like dental, skin, respiratory, and urinary tract infections. It also treats acne, Lyme disease, malaria, and certain sexually transmitted diseases. Doxycycline hyclate is a light-yellow crystalline powder which is soluble in water, while doxycycline monohydrate is very slightly soluble in water. Doxycycline is bacteriostatic, inhibiting bacterial protein synthesis due to disruption of transfer RNA and messenger RNA at ribosomal sites. Doxycycline hyclate is indicated for use in the treatment of chronic adult periodontitis for a gain in clinical attachment, reduction in probing depth, and reduction in bleeding on probing.

Minocycline is a tetracycline analog, having a 7-dimethylamino and lacking the 5 methyl and hydroxyl groups, which is effective against tetracycline-resistant staphylococcus infections. Minocycline has many brand names one of them is minocin, Minocin is indicated in the treatment of the following infections due to susceptible isolates of the designated bacteria: Rocky Mountain spotted fever, typhus fever and the typhus group, Q fever, rickettsialpox and tick fevers caused by rickettsiae. Respiratory tract infections caused by Mycoplasma pneumoniae. Lymphogranuloma venereum caused by Chlamydia trachomatis. Psittacosis (Ornithosis) due to Chlamydophila psittaci etc. Minocycline is indicated for the treatment of infections caused by the following Gram-negative bacteria when bacteriologic testing indicates appropriate susceptibility to the drug: Escherichia coli. Enterobacter aerogenes. Shigella species etc. MINOCIN also is indicated for the treatment of infections caused by the following Gram-positive bacteria when bacteriologic testing indicates appropriate susceptibility to the drug: Upper respiratory tract infections caused by Streptococcus pneumoniae. Skin and skin structure infections caused by Staphylococcus aureus (Note: Minocycline is not the drug of choice in the treatment of any type of staphylococcal infection, etc. When penicillin is contraindicated, minocycline is an alternative drug in the treatment of the following infections: Meningitis due to Neisseria meningitidis. Syphilis caused by Treponema pallidum subspecies pallidum. Yaws caused by Treponema pallidum subspecies pertenue, etc. Minocycline passes directly through the lipid bilayer or passively diffuses through porin channels in the bacterial membrane. Minocycline inhibits protein synthesis by binding to 30S and possibly 50S ribosomal subunits of susceptible bacteria.