This is a two-site, three-arm, open-label, pilot randomized controlled trial of bone anti-resorptive therapy during ART initiation in HIV-infected adults. Thirty (30) treatment-naïve HIV-infected adults initiating eligible first-line ART regimens will be randomized in a 1:1:1 fashion to one of the following three arms:

1. no bone anti-resorptive therapy (standard of care)
2. concomitant initiation of a 24 week course of co-formulated alendronate/vitamin D;
3. a 24 week delay in initiation of a 24 week course of alendronate/vitamin D

Assessments (including clinical evaluation, questionnaires, adherence, basic laboratory evaluation, and BMD measurement) will be performed at baseline, 24 and 48 weeks. The primary objective will involve calculation of σ and ρ using all data; δ will be estimated by comparing the two alendronate arms pooled to the no-treatment arm.

Inclusion Criteria:

• Documented HIV-1 infection
• Adult (aged >18 years or as per local guidelines)
• Premenopausal, if female
• Antiretroviral-naïve
• Starting first-line ART including tenofovir/emtricitabine with either efavirenz (co-formulated as Atripla®) or elvitegravir, cobicistat (co-formulated as Stribild®)
• Low (<10%) ten-year fracture risk as assessed by the FRAX score validated for Canadian populations

Exclusion Criteria:

• Presence of established osteoporosis at baseline as determined by BMD measurement
• Prior or current use of any bone anti-resorptive therapy (eg. bisphosphonate, estrogens with the exception of oral contraceptive pills, etc.)
• Inability to communicate in English
• Creatinine clearance <35 mL/min (using Cockcroft-Gault formula)
• Hypersensitivity to alendronate, other bisphosphonates, or any component of the formulation
• Hypocalcemia
• Abnormalities of the esophagus which delay esophageal emptying such as stricture or achalasia
• Inability to stand or sit upright for at least 30 minutes
• Pregnancy, active plans to become pregnant, or lactation