2© paradigm publishing, inc. chapter 6 the skeletal system and drug therapy

© Paradigm Publishing, Inc. 2

Chapter 6

The Skeletal System and Drug Therapy


Chapter 6

Topics

• Anatomy and Physiology of Bones and Joints • Osteoporosis • Arthritis• Herbal and Alternative Therapy


Anatomy and Physiology of Bones and Joints

Bones• Provide structure and support for the body• Provide movement along with muscle and protect organs• Long bones, such as the femur, contain marrow, the

birthplace for blood cells• All bones store calcium and maintain its balance

Osteoclasts break down bone tissue, releasing calcium Osteoblasts take calcium from blood and build bone

• Grow and increase in density at the greatest rate during childhood and continue to build into the 30s Bone density gradually decreases over time



Anatomy of the Skeletal System



MicroscopicView of BoneOsteoclasts and osteoblasts provide bone homeostasis, a continual process that grows and repairs bone



Anatomy of a Joint (Articulation) The ends of bones are coated with cartilage and cushioned from friction by the synovial membrane and synovial fluid


Osteoporosis

Facts about Osteoporosis • Is a reduction in bone density, resulting in weakened bones

and fractures• Occurs when bone density decline accelerates abnormally• Causes fractures in the hips, spine, and wrists

Hip fractures can be life threatening for older patients• 90% of patients with osteoporosis are women• Risk Factors: female, Caucasian, family history, small body

frame, smoking, heavy caffeine intake, low calcium intake• Estrogen promotes bone density and estrogen levels

decreases after menopause


Osteoporosis

Screening Tests for Osteoporosis• Many pharmacies provide screening tests• BMD machines use x-ray and ultrasound• Usually measure the heel; good estimate of hip and spine• Pharmacists and technicians can be trained to perform test• Result of BMD provides a T-score which is estimate of risk• If at risk, patients can make lifestyle changes

Add weight-bearing exercise, eat foods high in calcium, quit smoking, and decrease caffeine intake

• Diagnosis of osteoporosis may require drug therapy


Osteoporosis

Drugs for Osteoporosis: Calcium• Healthy adults should get 1,000 mg of calcium a day• Patients with osteoporosis, people over 65, and women

after menopause should get 1,500 mg of calcium a day• Daily calcium total obtained through diet and dietary

supplements• Calcium dietary supplements

Various products Routes: oral; several dosage forms Dose: divided doses; only 500–600 mg of calcium

is absorbed at a time


Osteoporosis

Drugs for Osteoporosis: Calcium (continued) Side Effects (common): nausea, vomiting, and

constipation Side Effect (severe): excess calcium can cause kidney

stones Caution: do not take if kidney stone history Caution: do not take with quinolone antibiotics,

tetracyclines, or iron supplements


Osteoporosis

Drugs for Osteoporosis: Vitamin D• Improves calcium absorption in the GI tract and helps

other osteoporosis agents work more effectively• In fish, milk, breakfast cereals, and exposure to sunlight• Often is a combination product with calcium• Recommended daily requirements are 400 IU but many

physicians prescribe up to 1,100 IU a day• Indications: osteoporosis and osteopenia (high risk for

developing osteoporosis)• Side Effects: nausea, vomiting, and edema (swelling)• Cautions: hypercalcemia and kidney problems


Osteoporosis

Drugs for Osteoporosis: Bisphosphonates• Mechanism of Action: inhibit osteoclasts from removing

calcium from bone tissue; prevent bone breakdown• Indications: mainly osteoporosis, Paget’s disease, and

some bone and spinal injury cases• Dosage Forms: variety of oral and infusion choices• Side Effects: headache, nausea, vomiting, diarrhea,

constipation, abdominal pain, and indigestion• Side Effects (severe, rare): insomnia, anemia, osteonecrosis• Cautions: If oral, take on an empty stomach with water• Storage for IV: refrigerate and then use within 24 hours


Osteoporosis

Drugs for Osteoporosis: SERMs• Available SERMs: Raloxifene (Evista), tamoxifen (Nolvadex),

and toremifene (Fareston)• Mechanism of Action: work as estrogen receptors that

mimic the effects of estrogen on bone mineral density Do not increase risk of breast or uterine cancer

• Side Effects of Raloxifene: hot flashes, headache, diarrhea, joint pain, leg cramps, and flulike symptoms Side Effects (severe): deep vein thrombosis or blood

clots Cautions: Do not take if prolonged immobility


Osteoporosis

Drugs for Osteoporosis: Human Parathyroid Hormone• Teriparatide (Forteo) is a human parathyroid hormone• Mechanism of Action: supplements the body’s production

of parathyroid hormone Regulates the calcium–phosphate balance and

stimulates new bone growth• Indication: very severe osteoporosis; used short-term• Cautions: associated with osteosarcoma; do not take if

have Paget’s or risk for bone cancer• Patients taught how to use injector; drug kept refrigerated


Your Turn

Question 1: What is a restriction of raloxifene, a SERM used for osteoporosis?

Answer: Raloxifene should not be taken if prolonged immobility is anticipated.

Question 2: What is the purpose of taking vitamin D with calcium?

Answer: Vitamin D improves calcium absorption from the GI tract. It also helps other osteoporosis agents work more effectively.


Arthritis

Arthritis and Osteoarthritis (OA)• Arthritis

Is the most common joint disorder and it affects millions• OA

Is the most common type of arthritis Caused by wear and tear on joints that comes with age;

onset is usually after age 40 or 50Joint cartilage erodes and causes painful rubbing

Large joints such as knees, shoulder, and hips affected first

Symmetry often not present Morning stiffness is prominent but is relieved by activity


Arthritis

Rheumatoid Arthritis (RA)• Is an abnormal process in the immune system that

destroys the synovial membrane and produces inflammation in the joint

• Small joints (fingers, wrists, and elbows) affected first• Symmetry often present• Deformation of the joints can be disabling• Morning stiffness and pain are not relieved

after an hour or by activity• Two lab tests to help diagnose are ESR and RF• Disease is not curable but can be slowed with drug therapy


Arthritis

Gouty Arthritis (Gout)• Is a condition in which excessive uric acid accumulates in

the blood and urate crystals then form in the synovial fluid and irritate joints

• Joint pain and swelling often first occur in the big toe Can cause kidney damage without drug therapy

• Drugs that predispose someone to gout are diuretics, salicylates, nicotinic acid (niacin), ethanol, cytotoxic agents

• Certain foods rich in purine (amino acid), like red meat, also implicated in gout

• Chronic preventive therapy may be prescribed


Arthritis

Drugs for OA• Reduce pain and inflammation but do not cure

Severe OA may require surgery or joint replacement• Other remedies include physical therapy, cold/hot packs

massage, and rest

Drugs for OA: Acetaminophen • First-line choice that controls pain, not inflammation

Route: oral, taken multiple times a day

Drugs for OA: NSAIDs• Mechanism of Action: inhibit enzymes COX-1 and COX-2 from

producing prostaglandins


Arthritis

Drugs for OA: NSAIDs (continued)• Are good when inflammation is the main cause of pain or

acetaminophen no longer works• Indications: mild to moderate pain, including arthritis• Side Effects: headache, diarrhea, nausea,

constipation, and occasional dizziness and drowsiness• Side Effects of GI Tract: indigestion, heartburn, abdominal

pain, bleeding, ulcer, or anemia (from blood loss)• Routes: all oral; some not chewed or crushed• Cautions: renal (kidney) problems, fluid accumulation,

drug interactions; do not take with aspirin


Arthritis

Pain Pathway• Prostaglandins

promote inflammation and connect to pain receptors to trigger the pain response

Protect the GI lining against erosion from gastric acid


Arthritis

Drugs for OA: COX-2 Inhibitors• Celecoxib (Celebrex) is the only COX-2 inhibitor available• Mechanism of Action: inhibits COX-2 from production of

prostaglandins that cause pain and inflammation Does not inhibit COX-1 from protecting GI lining

• Indications: arthritis pain; pain with ulcers or GI bleeding• Side Effects: headache, abdominal pain, heartburn,

nausea, and occasional GI irritation and bleeding• Routes: oral; can be taken short- or long-term• Cautions: monitor heart function


Your Turn

Question 1: A patient is diagnosed with mild OA. What is the physician likely to order?

Answer: The drug of choice for OA is acetaminophen.

Question 2: How is the function of a COX-2 inhibitor different than the function of a NSAID?

Answer: A COX-2 inhibitor blocks COX-2, an enzyme that promotes the production of the prostaglandins that cause pain and inflammation. NSAIDs block both COX-1 and COX-2, which cuts off prostaglandins that protect the lining of the GI tract.


Arthritis

Drugs for RA• Goal of drug therapy is to maintain mobility and delay

disability for as long as possible• Can improve pain and slow the disease progression

Drugs for RA: DMARDs• Indications: slow disease progression of RA and used as

immunosuppressants used after organ transplant• Mechanism of Action: inhibit immune system to slow

down destruction of joint tissue• Best started within first 3 months from diagnosis; taken on

chronic basis to maintain disease and symptom control


Arthritis

Drugs for RA: DMARDs (continued)• Disease remission can sometimes be achieved• Early therapy slows joint destruction• Side Effects: vary among agents; effects can mimic those

of chemotherapy and are unpleasant• Routes: oral (some not chewed or crushed), IM, IV, and SC• Cautions: increased incidence of infection; avoid people

who are ill and use other precautions to prevent infection• Cautions: many cause kidney damage• Preparation and Storage: some DMARDs have special

mixing and storage; refrigerate injectable forms


Arthritis

Drugs for Gouty Arthritis• Treatment during an acute gout attack differs from

prevention of gout attacks• Indications (chronic, low-dose therapy): a very severe

attack or repeated gout exacerbations within a year• Mechanism of Action: lower uric acid levels in blood and

reduce inflammation within joints caused by urate crystals• Colchicine is drug of choice to lower uric acid in acute and

chronic attacks; used in preventive therapy at a lower dose• Triamcinolone Injection is a corticosteroid administered

directly into the joint for gout attack


Arthritis

Drugs for Gouty Arthritis (continued)• Allopurinol is the most frequently prescribed drug for gout

prophylaxis• Side Effects (common): vary among agents; includes

diarrhea, nausea, rash, vomiting, and headache• Routes: all are oral except triamcinolone • Administration of Triamcinolone: intra-articular (injected

directly into the joint) to relieve pain and inflammation• Cautions for Probenecid: drink plenty of water

(can harm the kidneys); do not take with aspirin


Herbal and Alternative Therapies

• Glucosamine Taken to improve pain and stiffness from OA Studies do not support that it is effective Side Effects: nausea, heartburn, diarrhea, and

constipation Caution: do not take if allergic to shellfish

• Chondroitin Taken with glucosamine for hip and knee OA Studies do not support that it is effective Side Effects: nausea, heartburn, diarrhea, constipation Side Effects (rare): eyelid swelling, lower limb swelling,

hair loss, and allergic reaction


Summary• Bisphosphonates and SERMs used to treat osteoporosis• Calcium and vitamin D are taken for osteoporosis• Acetaminophen is the first-line choice of therapy for OA• Many patients with OA progress to long-term NSAIDs• DMARDs halt progression of RA, and NSAIDs are used to

treat pain• DMARDs have many side effects and are difficult to take• Drugs such as colchicine and allopurinol are used for gout

2© paradigm publishing, inc. chapter 6 the skeletal system and drug therapy

Documents

bones store calcium

joints paradigm publishing

physiology of bones

calcium osteoblasts

joints bones

osteoporosis drugs

excess calcium

repairs bone slide