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What are the different types of tetracyclines?
assistant
1.  Tetracycline is a broad-spectrum antibiotic that can be used to treat many bacterial infections, such as acne, bronchitis, and pneumonia.
2.  Doxycycline is a semi-synthetic tetracycline antibiotic that has been approved for use in humans since 1967.
3.  Minocycline is a second-generation tetracycline antibiotic that is used to treat acne, rheumatoid arthritis, and other inflammatory conditions.