What is the distinction between doxycycline and doxycycline hydrochloride?

Doxycycline is available in several different salts: Doxycycline hydrochloride (hyclate), Doxycycline monohydrate, doxycycline carrageenate, doxycycline calcium and doxycycline phosphate (fosfatex).

Doxycycline Hydrochloride:

Doxycycline hcl appearance - yellow powder shelf life of antibiotic anti-infective drug substance of doxycycline, also known as doxycycline, This product is light yellow or yellow crystalline powder, bitter, [Uses] antibiotic anti-infective pharmaceutical raw materials, this product tetracycline antibacterial spectrum and the same long-lasting, efficient, and antibacterial effects of tetracycline stronger than 10-fold resistant to tetracycline is still valid, mainly for respiratory tract infections, chronic bronchitis, sexually transmitted disease and urinary tract infection and so on.

Doxycycline to reduce the development of drug-resistant bacteria and maintain effectiveness of doxycycline and other antibacterial drugs, doxycycline should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.

Doxycycline is indicated for the treatment of the following infections:

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) caused by Chlamydia psittaci. Trachoma caused by Chlamydia trachomatis, although the infectious agent is not always eliminated as judged by immunofluorescence.Inclusion conjunctivitis caused by Chlamydia trachomatis. Uncomplicated urethral, endocervical or rectal infections in adults caused by Chlamydia trachomatis. Nongonococcal urethritis caused by Ureaplasma urealyticum. Relapsing fever due to Borrelia recurrentis.

Doxycycline is also indicated for the treatment of infections caused by the following gram-negative microorganisms:

Chancroid caused by Haemophilus ducreyi. Plague due to Yersinia pestis (formerly Pasteurella pestis). Tularemia due to Francisella tularensis (formerly Pasteurella tularensis). Cholera caused by Vibrio cholerae (formerly Vibrio comma). Campylobacter fetus infections caused by Campylobacter fetus (formerly Vibrio fetus). Brucellosis due to Brucella species (in conjunction with streptomycin). Bartonellosis due to Bartonella bacilliformis. Granuloma inguinale caused by Calymmatobacterium granulomatis.

Because many strains of the following groups of microorganisms have been shown to be resistant to doxycycline, culture and susceptibility testing are recommended.

Doxycycline is indicated for treatment of infections caused by the following gram-negative microorganisms, when bacteriologic testing indicates appropriate susceptibility to the drug:

Escherichia coli; Enterobacter aerogenes (formerly Aerobacter aerogenes)
Shigella species; Acinetobacter species (formerly Mima species and Herellea species); Respiratory tract infections caused by Haemophilus influenzae. Respiratory tract and urinary tract infections caused by Klebsiella species.

Doxycycline is indicated for treatment of infections caused by the following gram-positive microorganisms when bacteriologic testing indicates appropriate susceptibility to the drug:

Upper respiratory infections caused by Streptococcus pneumoniae (formerly Diplococcus pneumoniae).

Skin and skin structure infections caused by Staphylococcus aureus.

Anthrax due to Bacillus anthracis, including inhalational anthrax (post-exposure): to reduce the incidence or progression of disease following exposure to aerosolized Bacillus anthracis.

Doxycycline is not the drug of choice in the treatment of any type of staphylococcal infections.

When penicillin is contraindicated, doxycycline is an alternative drug in the treatment of the following infections:

Uncomplicated gonorrhea caused by Neisseria gonorrhoeae.
Syphilis caused by Treponema pallidum.
Yaws caused by Treponema pertenue.
Listeriosis due to Listeria monocytogenes.
Vincent's infection caused by Fusobacterium fusiforme.
Actinomycosis caused by Actinomyces israelii.
Infections caused by Clostridium species.

In acute intestinal amebiasis, doxycycline may be a useful adjunct to amebicides.

In severe acne, doxycycline may be useful adjunctive therapy.

The side effects are more or less the same, however it would be best to seek the advice of a doc/pharmacist for more details.

Take care, best wishes!