Block 4 Drugs

Question 1

Acetazolamide

Answer 1

Systemic Carbonic Anhydrase Inhibitor

Use:

• Taken orally for prophylaxis and treatment of altitude sickness, no longer a primary treatment for glaucoma.
• Reduces intraocular pressure (IOP) by 50-60%.

Mechanism:

• Direct inhibition of carbonic anhydrase (orally and parenterally)
• Reduction in aqueous humor production due to decreased bicarb concentration in ocular fluid.

Adverse Effects:

• Incidence and severity are dose related

Question 2

Brimonidine (same class as apraclonidine, clonidine)

Answer 2

Topical Selective Alpha 2 Adrenegic Agonist

Use:

• Treating open-angle glaucoma and ocular HTN

Mechanism:

• potent, 1000-fold more selective for alpha 2 receptor than alpha 1
• decreases intraocular pressure (IOP) w/o causing mydriasis, by reducing aqueous humor production and increasing uveoscleral aqueous humor outflow

Adverse effects:

• Xerostomia (drymouth), hyperemia, ocular irritation, headache, blurred vision

Question 3

Dorzolamide

Answer 3

Topical Carbonic Anhydrase Inhibitor

Use:

• Treating glaucoma and ocular HTN
• Administered topically to the eye

Mechanism:

• Highly specific inhibitor of an isoenzyme of carbonic anhydrase (CA-II), which exerts selective control of aqueous production and intraocular pressure (IOP)
• Decreases bicarb concentration in ocular fluid which results in decreased aqueous humor secretion and intraocular pressure is subsequently lowered.

Adverse effects:

• Appears to have no clinically significant biochemical or hematologic effects when administered topically to the eye

Question 4

Latanoprost

Answer 4

Topical F 2-alpha Prostaglandin Agonist

Use:

• Treating elevated intraocular pressure

Mechanism:

• It is a prodrug administered topically to the eye. It is absorbed through the cornea where it is hydrolyzed to the acid form to become biologically active
• Increased uveoscleral outflow of aqueous humor results in reduced intraocular pressure.

Side effects:

• Can gradually change eye color by increasing amount of brown pigment in iris by increasing the number of melanosomes in melanocytes

Question 5

Mannitol

Answer 5

Parenteral Osmotic Diuretic

Use:

• To reduce intraocular pressure (same mechanism as reducing cerebral edema, intracranial pressure, cerebrospinal fluid pressure)
• Administered IV

Mechanism:

• Systemically, it elevates blood osmolality which increases the osmotic gradient between blood and tissues, facilitating the flow of fluid out of tissues (including the brain and eye) and into the interstitial fluid and blood.

Side effects:

• Pulmonary congestion, fluid and electrolyte imbalance, acidosis, electrolyte loss, dryness of mouth, thirst, marked diuresis, urinary retention, edema, headache, blurred vision

Question 6

Timolol

Answer 6

Topical Nonselective Beta-Adrenergic Receptor Antagonist

Use:

• Treating glaucoma
• Reduction of elevated or normal intraocular pressure occurs irrespective of the presence of glaucoma

Mechanism:

• Blocks both beta 1 and beta 2 receptors.
• Reduces intraocular pressure by reducing aqueous humor production or possibly outflow (beta receptors in the ciliary epithelium are linked to the Na-K ATPase)
• When beta receptor stimulation increases movement of Na+ into the aqueous humor, water is drawn in osmotically, so this transfer rate is decreased as beta receptors are blocked.

Adverse effects:

• visual acuity, pupil size, and accommodation do not appear to be affected

Question 7

Buprenorphine

Answer 7

Mu receptor opioid partial agonist (aka mixed opiate agonist/antagonist)

Question 8

Codeine

Answer 8

Moderate Mu-receptor Opioid Agonist

Question 9

Hydromorphone

Answer 9

Moderate to Strong Mu-receptor opioid agonist (more potent than morphine)

Question 10

Dextromethorphan

Answer 10

Oral, Nonprescriptive Drug Used as an Anti-tussive (cough suppressant)

This d-isomer opioid lacks significant opioid activity except for cough suppression

Question 11

Diphenoxylate

Answer 11

Opioid Agonist Used to Treat Diarrhea

Inhibits GI motility, slows excess GI propulsion,

HAS NO ANALGESIC or OPIATE-LIKE effects

Question 12

Fentanyl

Answer 12

Analgesic - Strong agonist at Mu and Kappa Opioid Receptors

Nearly 100x more potent than morphine, has longer half-life and duration of action than morphine

Parenterally administered via transmucosal or transdermal routes

Question 13

Hydrocodone

Answer 13

Analgesic - moderate mu-receptor opioid agonist

Combined with acetaminophen (Vicodin) for moderate to moderately-severe pain.

Also used as an antitussive

Question 14

Loperamide

Answer 14

Opioid agonist used for the treatment of diarrhea

NO ANALGESIC or OPIATE-LIKE effects, even at high doses. No tolerance to antidiarrheal effect, NO PHYSICAL DEPENDENCE

For the control and relief of acute, nonspecific diarrhea as well as chronic diarrhea associated with inflammatory bowel disease.

Interferes with peristalsis by direct action on circular and longitudinal muscles of the intestinal wall to slow motility