Levothyroxine (T4) & Liothyronine (T3) for hypothyroidism -- Dosing; DIs; Monitoring; AEs
- Dosing: on empty stomach, 30 min before breakfast
- DIs: 1. bile acid resins, sucralfate, antacids, mg salts, Fe supps, CATIONS decr T3/4 absorp. 2. Raloxifene - decr T3/4 absorp => incr dose; SPACE 12H. 3. Fx of warfarin enhanced. 4. Orlistat => hypoT - admin 4H apart. 5. T hormones incr cardiac response to catecholeamines => incr risk dysrhythmias.
- Monitor: TSH 6-8 wks into treatment
- AEs: **Acute OD = thyrotoxicosis**; chronic OD => incr bone loss & risk of afib
Compare/Contrast Propylthiouracil (PTU) and Methimazole, both used for hyperthyroidism.
- BOTH: inhibit thyr horm synth; can => agranulocytosis - do CBC w/ diff
- PTU: Acts in periphery to suppress conversion of T4 => T3; if must, use THIS AGENT in preg
- Methimazole: DOES NOT act in periph; DON'T use in preg or lact!
How do bisphosphonates affect osteoporosis?
Inhibit osteoclast activity => decr bone resorption and turnover
What are the concerns with ALL bisphosphonates used to treat osteoporosis?
- Esophagitis: take w/ full glass water; don't lie down 30-60min; completely empty stomach; watch out for other GI irritants
- Osteonecrosis of the jaw
Describe the differences in admin forms of the bisphosphonates: Alendronate, Risendronate, Ibandronate, Zoledronic Acid
- Alendronate: multiple PO forms
- Risendronate: multiple PO forms
- Ibandronate: Daily and monthly PO; and IV!
- Zoledronic Acid: ONLY IV!!
Ibandronate and Zoledronic Acid (bisphosphonates) have unique characteristics. What are they?
- Ibandronate: contraindicated in severe renal impairment (CrCl < 30); ONLY for treating postmenop osteoporosis
- Zoledronic Acid: PT must be well-hydrated to prevent renal impair; contraindicated in hypocalcemia; give APAP or ibuprofen post-admin to minimize infus-induced HA, fever, muscle aches
- Both: both have IV forms! (ZA is only IV)
What agent for osteoporosis causes bone building?
SERMs/Raloxifene: How do they work and what are their AEs and DIs?
- Estrogen-like effect on bone: inhibits bone resorption and turnover
- AEs: DVT, VTE, thrombosis, stroke => DO NOT USE w/ ESTROGEN; preg cat X
- DIs: thyr horms - separate by 12H; bile acid resins - don't combo, may decr ralox
- Also: in contrast to estrogen, raloxifene protects against endomet & breast cancer
Calcitonin-Salmon [Miacalcin]: MoA? Admin? AEs? DIs?
- MoA: 1. inhibits resorption; 2. inhib tub resorp Ca => incr excretion
- Admin: intranasal, SQ, IM
- AEs: hypersensitivity, flushed face/hands, nasal irrit/dryness
- DIs: No signif ones!
Teriparatide [Forteo]: MoA? Admin? AEs? DIs?
- = ONLY drug that incr bone formation!
- MoA: incr bone depos AND resorp
- Admin: daily SQ
- AEs: risk for osteosarcoma (Pagets) if @ risk; hyperuricemia; transient hypercalcemia; ortho hypo
- DIs: digoxin => additive cardiotoxic fx
Compare/Contrast the MoAs of agents for osteoporosis - bisphosphonates, SERMs (Raloxifene), Calcitonin-Salmon (Miacalcin), Teriparatide.
- Bisphosphonates: decr bone resorption
- SERMs (Ralox): estrogenic fx => inhib bone resorp
- Calcitonin-Salmon (Miacalcin): inhib resorp, inhib tub resporp => incr excretion
- Teriparatide [Forteo]: incr bone depos and resorp