The purpose of this study is to compare the single-dose bioequivalence of Par and Oclassen doxycycline monohydrate, 100 mg.

To compare the single-dose bioequivalence of Par and Oclassen (Monodox(R)), 100 mg doxycycline under fasting conditions.

Inclusion Criteria:

• Males, non-smokers, between 18-55 years of age
• Subjects' weight will be within 15% of their ideal weight based on the Table of "Desirable Weight of Adults", Metropolitan Life Insurance Company, 1983.
• Subjects should read, sign, and date an Informed Consent Form prior to any study procedures
• Subjects must complete all screening procedures within 28 days prior to the administration of the study medication.

Exclusion Criteria:

• Clinically significant abnormalities found during medical screening
• Any clinically significant history of ongoing gastrointestinal problems or problems known to interfere with the absorption, distribution, metabolism or excretion of drugs (e.g. chronic diarrhea, inflammatory bowel diseases).
• Clinically significant illnesses within 4 weeks of the administration of study medication.
• Abnormal laboratory test judged clinically significant.
• ECG or vital signs abnormalities (clinically significant).
• History of allergic reactions to doxycycline or other related drugs (e.g., chlortetracycline, demeclocycline, minocycline and tetracycline).
• History of allergic reactions to heparin.
• Any food allergies, intolerances, restrictions, or special diet which in the opinion of the medical sub-investigator, contraindicates the subject's participation in this study.
• Positive urine drug screen (see section VIII) at screening
• Positive testing for hepatitis B, hepatitis C or HIV screening.
• Use of an investigational drug or participation in an investigational study, within 30 days prior to administration of the study medication.
• Recent donation of plasma (500 mL) within 7 days or recent donation or significant loss of whole blood (450 mL) with 56 days prior to administration of the study medication.
• History of significant alcohol abuse within six months of the screening visit or any indication of the regular use of more than two units of alcohol per day (1 Unit = 150 mL of wine or 360 mL of beer or 45 mL of alcohol 40%)
• Recent history of drug abuse or use of illegal drugs: use of soft drugs (such as marijuana, pot) within 3 months of the screening visit or hard drugs (such as cocaine, phencyclidine (PCP), crack) within 1 year of the screening visit.
• Subjects who have taken prescription medication 14 days preceding administration of study medication or over the counter products 7 days preceding administration of study medication, except for topical products without systemic absorption.
• Subjects who have taken any drugs known to induce or inhibit hepatic drug metabolism within 30 days prior to administration of the study medication (examples of inducers: barbiturates, carbamazepine, phenytoin, glucocorticoids, rifampin/rifabutin; examples of inhibitors: antidepressants, cimetidine, diltiazem, erythromycin, ketoconazole, MAO inhibitors, neuroleptics, verapamil, quinidine).
• Subjects who have undergone clinically significant surgery 4 weeks prior to the administration of the study medication.
• Any reason which, in the opinion of the medical sub-investigator, would prevent the subject from participating in the study.