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Musculoskeletal System > 2 - Pharmacology > Flashcards

2 - Pharmacology Flashcards

1
Q

What are the two groups of skeletal muscle relaxants? Describe their characteristics overall.

A

NMS Blockers - used to produce muscle paralysis in order to facilitate surgery for artificial ventilation (CNS)

Spasmolytic - reduce abnormally elevated muscle tone/spasticity without paralysis (e.g. baclofen, dantrolene, etc…). Mostly used for muscle strains or back pain/spasms

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2
Q

Spasmolytics are traditionally known as “centrally acting”, but which member is peripherally acting?

A

Dantrolene

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3
Q

Give some (3) examples of the traditional central acting spasmolytics.

A

Baclofen, diazepam, tizanidine, botox

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4
Q

Describe the action of Baclofen

A

Central acting spasmolytic
GABA analog***
Acts within spinal chord to suppress hyperactive reflexes involved in regulation of muscle movement

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5
Q

Describe the action of diazepam

A

Central acting spasmolytic
Facilitates GABA mediated inhibition on motor neurons in the spinal cord
Can be used in patients with muscle spasm OF ANY ORIGIN, including local trauma.

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6
Q

Describe the action of dantrolene

A

Peripherally acting spasmolytic
Suppresses calcium release from SR, thus decreasing ability to contract muscle
Acts directly on the skeletal muscles

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7
Q

Doc wants to prescribe a muscle relaxant with minimal effects on smooth/cardiac muscle, which spasmolytic drug would be prescribe?

What are possible adverse effects of this drug?

A

Dantrolene

May cause significant decrease in contractile strength of skeletal muscles

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8
Q

Name an spasmolytic drug that is indicated for the treatment of malignant hyperthermia.

A

Dantrolene

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9
Q

Name a drug that can be used to relieve spasticity associated with MS, Cerebral Palsy, and Spinal Cord injuries

A

Dantrolene

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10
Q

Describe the action of Tizanidine

A

Alpha 2 agonist, which acts pre-synaptically in the spinal cord
Indicated in patients with spasms resulting brain or spinal injuries

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11
Q

What are the differences between spasm and spacticity?

A

Spasms - sudden, violent, involuntary contractions of a muscle or muscle group. (LOWER MOTOR NEURONS)

Spasticity - an increase in the passive stretch resistance of a muscle or muscle group (i.e. increased muscle stiffness/tone) causes stiff/awkward movements. (UPPER MOTOR NEURONS)

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12
Q

When is baclofen preferred to dantrolene?

A

When the patient has spasticity associated with weakness.

Note: It does not relieve parkinson’s disease

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13
Q

What is a spastic disorder that baclofen is not effective in treating?

A

Parkinson’s disease

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14
Q

How do you minimize the sedation side effects of diazapam?

A

initiate therapy at low doses

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15
Q

What are some contraindications of baclofen?

A

Pt. should avoid taking CNS depressants and alcohol because baclofen will potentiate action of these drugs

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16
Q

What is malignant hyperthermia and what causes it?

A

Life threatening syndrome that can be triggered by any general anesthetic and by succinyl choline (NMS blocker)

Massive release of calcium from the SR causes uncontrolled muscle contractions that generate massive amounts of body heat

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17
Q

What type of drug can be used to treat malignant hyperthermia?

A

Dantrolene (skeletal muscle relaxant) - acts on SR to block calium release

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18
Q

What is the major drawback of dantrolene?

A

Liver Toxicity

Tests for liver function should be performed prior to treatment and throughout the period of treatment

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19
Q

When is diazepam preferred over dantrolene?

A

In patients whose strength is questionable

In patients with poor liver function?

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20
Q

When may tizanidine be chosen over clonidine?

A

It may be chosen due to the fact that its much less anti-hypertensive than clonidine

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21
Q

What is the mechanism of action of Botox?

A

disrupts neurotransmission by inhibiting the release of acetylcholine at the presynaptic cholinergic nerve terminals.

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22
Q

What are the 5 tetracyclins still in use today?

A
  1. Tetracycline
  2. Demeclocycline
  3. Doxycycline
  4. Minocycline
  5. Tigecycline
23
Q

What is the mechanism of action of the tetracyclines?

A

Enters through passive diffusion and energy dependent active transport
Binds the 30s and blocks addition of amino acids to the growing peptide.

24
Q

What are the 3 bacterial resistance mechanisms against tetracyclines. Explain Each.

A
  1. Increased efflux by active transport (expression of Tet (AE) and Tet (K)
    • Most important resistance mechanism
  2. Production of ribosome protection protein that interferes with binding of tetracycline to ribosome (expression of Tet(M)
  3. Enzymatic inactivation
25
Q

What is the significance of tigecycline? (given IV btw)

A

It is unaffected by most resistance mechanisms so it is saved as a last resort, not used immediately (to prevent increased chance of resistance acquisition)

26
Q

What is the Tet (AE) form of resistance? Drugs resisted?

A

Associated with increased efflux resistance to tetracyclines

Resistant to Tetra, Doxy, and Mino
NOT Tige

27
Q

What is the Tet (K) form of resistance? Drugs resisted?

A

Associated with increased efflux resistance to tetracyclines

Resistant to Tetra
NOT - Doxy, Mino, or Tige

28
Q

What is the Tet (M) form of resistance? Drugs resisted?

A

Associated with the production of ribosome protection proteins that interfere with tetracycline binding to the 30s ribosomal unit

Resistant to tetra, doxy, and mino
NOT tige-

29
Q

Categorize the tetracyclines by bioavailability and t1/2

A 
Tetra- 60-70% and 6-8 h
Demeclo - 60-70% and 12 h
Doxy - 95-100% and 16-18 h 
Mino - 95-100% and 16-18 h 
Tige - POOR and 36 h
30
Q

What affects the absorption of tetracyclines?

A

Dairy Products, Antacids (cations e.g. Ca2+)
Also impaired by alkaline pH
Food doesnt really affect doxy and mino

31
Q

Which tetracycline has the best degree of tissue penetration?

A

Mino > Doxy > Tetra

32
Q

Why is minocycline indicated for prophylaxis of meningococcal infections (2nd line)

A

It has excellent tissue distribution, including into the tears and saliva

33
Q

How are tetra and demeclocycline metabolized and excreted from the body?

A

Excreted mainly in the bile and urine

34
Q

How is doxycycline eliminated from the body?

A

90% is eliminated by the intestinal tract in its inactive form

35
Q

How is minocycline metabolized/eliminated?

A

Mostly metabolized in the liver to inactive form

36
Q

How is tigecycline eliminated?

A

Primarily excreted in bile

Eliminated in feces in unchanged form

37
Q

Describe the indications of tetracyclines in general

A

Broad Spectrum + atypical pathogens:

  • Rickettsia
  • Mycoplasma Pneumoniae
  • Chlamydophila and Chalmydia species
38
Q

Describe a very important use for Tigecycline!

Why is it saved (2 reasons)

A

Not 1st line, but it is active against VRE (vanco resistant enterococci) and MRSA

  1. prevent resistance
  2. associated with increased mortality
39
Q

What types of infections is doxycycline the drug of choice for?

A

Rickettsia infections (even in young children)
Chlamydia infections
Early Lyme disease infections

40
Q

Adverse Effects of the tetracyclines?

A

Teeth and Bone discoloration
Allergic Skin Reactions and Photosensitivity (demeclocycline)
Contraindicated in pregnant women
Gastrointestinal Problems
Hepatotoxicity seen in tetra and mino (pregnant women more susceptible
Vertigo (minocycline)

41
Q

What is the mechanism of Clindamycin on pathogens?

A

Binds the 23s RNA of the 50s ribosomal subunit, interferes with peptide bond formation by interacting with both A and P sites

42
Q

What are the 3 mechanisms of bacterial resistance to clindamycin?

A
  1. Mutation of the ribosomal binding site
  2. Modification of the ribosomal binding site by a constitiutively expressed methylase
  3. Enzymatic inactivation
43
Q

How is Clindamycin metabolized and excreted?

A

Metabolized by the liver and excreted mainly by bile (active and inactive)

no dose adjustments needed in renal insufficient patients

44
Q

What does clindamycin do well?

A

Penetrates well into abcesses and concentrated by phagocytic cells

45
Q

What are the adverse effects of clindamycin?

A

*Pseudomembranous colitis - killing off normal flora allowing for C. Diff superinfection (release of cytotoxins that cause colitis)
GI symptoms

46
Q

What are the most common clinical uses of clindamycin?

A

Treatment of skin and soft tissue infections, caused by staph and strep, anerobic infections

47
Q

What antibiotic causes yellow pseudomembranous colitis? characterized by mucosal ulcerations,severe diarrhea and fever.

A

Clindamycin causeing a c diff superinfection

48
Q

What is the mechanism of Chloramphenicol action against pathogens?

A

Binds reversibly to the 50s ribosomal subunit, prevents binding of tRNA containing Amino acids which inhibits transpeptidation

49
Q

What is the major mechanism of bacterial resistance to chloramphenicol?

A

Inactivation of the drug directly via acetyltransferase

50
Q

Describe how chloramphenicol is metabolized

A

metabolized in the liver (requires dosage adjustments in pts. with liver problems.

51
Q

What are the adverse effects of chloramphenicols?

A

Aplastic Anemia
Gray Baby Syndrome (babies that lack glucuronic acid conjugation yet)
Dose-Dependent reduction of RBCs

52
Q

What are the most common clinical uses of chloramphenicol?

A

Reserved only for life-threatening situations due to its serious and sometimes fatal suppression of RBC production (Rickettsia, Bacterial Meningitis, Typhoid Fever)

53
Q

What would an autopsy of a person who died from adverse effects of chloramphenicol look like?

A

Widespread hemorrhage, pulmonary edema, bone marrow hypoplasia

Musculoskeletal System (21 decks)

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