Pharmacology Flashcards
Which of the following properties may increase the efficacy of a topical ophthalmic medication?
A. Prescribing the medication in suspension form
B. Decreased viscosity
C. Increased concentration of preservatives
D. Possessing a pH that is close to the physiological pH of the eye
D.
Explanation - An ophthalmic medication that possesses a pH that is as close to the natural pH of the tear film will generally cause less stinging and ocular irritation with instillation. A drop that results in stinging produces reflex tearing, which dilutes the topical medication, thereby decreasing its efficacy. A drug that results in ocular discomfort, for some patients, may also result in poor compliance with the dosing schedule.
Generally, medications that are in suspension form are not as beneficial as those in emulsion form due to poor patient compliance with shaking of the bottle prior to use to properly distribute the medication; this lack of compliance causes inadvertent non-uniform dosing. Increased viscosity of the medication, although possibly leading to varying degrees of vision blurring, offers better ocular retention and better performance. Although there is some debate regarding toxic effects on the cornea by preservatives, the majority of clinicians agree that if a drop is used with increased frequency, a preservative-free formulation is beneficial to the patient.
Scurvy results from a deficiency of what vitamin? A. Vitamin D B. Vitamin A C. Vitamin B D. Vitamin C
D.
Explanation - Vitamin C, also known as ascorbic acid, is a powerful antioxidant. It facilitates the absorption of dietary iron. It is also a cofactor in many enzymatic reactions, including the synthesis of collagen. Avitaminosis C results in scurvy caused by the creation of unstable collagen. Scurvy presents with general weakness, anemia, brown spots on the skin, spongy gums, petechial hemorrhages of the skin and mucous membranes, proptosis and feelings of paralysis, amongst other symptoms. Advanced cases are remarkable for open suppurative wounds, loss of teeth, and death. Interesting fact: Broccoli contains more vitamin C than oranges, 90mg/100mg vs. 50mg/100mg. The kakadu plum contains a whopping 3100mg/100mg of vitamin C!! Severe alcoholics can become victims of scurvy due to malnutrition.
A 54-year old female presents at your office with a very photobic, red right eye. Slit lamp exam reveals 3+ cells and flare in the anterior chamber. There is no evidence of inflammation in the left eye. You correctly diagnose her with iritis and initiate treatment. However, you also notice that her intraocular pressure is 31 mmHg. Which of the following glaucoma medications should NOT be prescribed?
A. Trusopt® (dorzolamide)
B. Timoptic® (timolol maleate)
C. Xalatan® (latanoprost)
D. Alphagan-P® (brimonidine tartrate)
C.
Explanation - Xalatan® should not be prescribed because prostaglandins are contraindicated when there is active ocular inflammation. Trusopt®, Timolol® and Alphagan-P® could all be used to decrease her intraocular pressure (IOP) but Alphagan-P® would be the best drop to prescribe. Alphagan-P® is frequently utilized to reduce IOP following anterior segment laser surgery, such as in argon laser trabeculoplasty, which frequently causes transient, mild inflammation.
It should be stated that clinically, if the left eye has normal IOP and you see flare due to iritis, this would indicate inflammatory glaucoma which is best treated with a steroid.
Which 3 of the following glaucoma medications are classified as beta blockers? (Select 3)
A. Brimonidine (Alphagan-P®) B. Unoprostone isopropyl (Rescula®) C. Carteolol HCL (Ocupress®) D. Timoptic Hemihydrate (Betimol®) E. Levobunolol HCL (Betagan®) F. Bimatoprost (Lumigan®)
C, D, E
Explanation - Alphagan-P® is an adrenergic alpha-2 agonist. Rescula® and Lumigan® are prostaglandins analogs. Betagan®, Ocupress® and Betimol® are all categorized as beta blockers. Beta-blockers serve to decrease intraocular pressure (IOP) by blocking respective beta receptors located in the ciliary body, thereby decreasing production of aqueous. Beta blockers also decrease the damaging effects of glaucoma by increasing outflow facility, resulting in a lowering of IOP. Note: beta blockers generally end in “olol”.
A deficiency of which of the following vitamins results in rickets in children and osteomalacia in adults?
A. Vitamin C
B. Vitamin A
C. Vitamin B
D. Vitamin D
D.
Explanation - Vitamin D plays a large role in regulating calcium and phosphate levels within the body. A major source of Vitamin D is sunlight; however, UV exposure can increase the risk of skin cancer. UV light converts Vitamin D to its active form, allowing for greater absorption of calcium in the gut. The calcium is then deposited into the bones, teeth etc. Dietary forms of Vitamin D include butter, eggs, margarine, fish liver oil, and fortified milk and juice.
Cyclosporine is commonly used topically to treat certain eye conditions including keratoconjunctivitis sicca (KCS). Which of the following is a known mechanism of action for cyclosporine?
A. Inhibition of T-cell activation
B. Antagonism of vitamin K
C. Stabilization of mast cells
D. Inhibition of cyclooxygenase (COX)
A.
Explanation - While the exact mechanism of action of cyclosporine remains controversial, it is generally accepted that cyclosporine inhibits calcineurin in CD4+ T helper cells which, under normal circumstances, are responsible for production of interleukin-2 (IL-2). IL-2 normally stimulates activation and proliferation of cytotoxic T cells and other helper T cells. Cyclosporine prevents this activation and acts as an anti-inflammatory. One of the major causes of KCS is autoimmune destruction of lacrimal cells by T cells. Therefore, topical cyclosporine can be protective. In all likelihood, there are likely additional mechanisms of action for cyclosporine in the treatment of KCS, but this is one of the most accepted mechanisms and is the best option from the choices given here.
The first-generation cephalosporins have a potential for cross-reactivity with which of the following drug classes?
A. Macrolides
B. Fluoroquinolones
C. Penicillins
D. Aminoglycosides
C.
Explanation - From a biochemistry perspective, first-generation cephalosporins and penicillin-based medications appear similar in that their physical pharmacological make-ups both possess a beta-lactam ring. Most studies purport that roughly 10% (although recent studies suggest 1% or less) of patients who are allergic to penicillin may also potentially exhibit an allergic response to the first-generation cephalosporins. The cross-reactivity between penicillins and cephalosporins is almost non-existent with the third-generation cephalosporins. Although the chances of a patient possessing a cross-reactivity between penicillin and cephalosporin drugs is very rare, it is best to prescribe an alternate antibiotic when a known allergy to penicillins exists.
Which of the following agents can be used for INTRAOCULAR surgical procedures?
A. Saline
B. Thimerosal
C. Balanced salt solution (BSS)
D. Benzalkonium chloride (BAK)
C.
Explanation - Thimerosal and BAK are microbial agents and can be used in small doses as preservatives on extraocular surfaces; however, if used intraocularly they will result in iritis, cataract formation, and death of corneal endothelial cells. Saline is not an acceptable intraocular irrigating solution because it does not contain the electrolytes needed to maintain proper isotonicity of the corneal endothelium (such as calcium, magnesium, glucose, sodium, potassium, etc.); this will result in swelling and lysis of the endothelial cells. BSS is frequently used for short-term intraocular surgeries as it is isotonic to ocular tissue and contains electrolytes that are needed for normal cell functions.
Which of the following vitamins is also known as thiamine?
A. Vitamin B3
B. Vitamin B1
C. Vitamin B6
D. Vitamin B2
B.
Explanation - Vitamin B1 is also known as thiamine. Thiamine is important for carbohydrate metabolism and the maintenance of neuronal tissue. Although rarely seen in the United States due to the fact that most foods are enriched with vitamins, a B1 deficiency can result in beriberi. Symptoms of beriberi include difficulty walking, loss of sensation in hands and feet, paralysis (due to deterioration of myelin sheath), nystagmus, speech difficulty/mental confusion, ophthalmoplegia, and congestive heart failure. Alcoholism can lead to beriberi due to malnutrition. Vitamin B2, also known as riboflavin, aids in the metabolism of nutrients. Avitaminosis B2 can result in decreased visual acuity due to corneal neovascularization, keratoconjunctivitis sicca, or cataract formation. Vitamin B3 (a.k.a. niacin) is responsible for fat and carbohydrate metabolism. A deficiency of Vitamin B3 can cause pellagra, which results in diarrhea, dementia, and dermatitis. Niacin can be used to treat hyperlipoproteinemia. Vitamin B6, also called pyridoxine, serves an important role as a coenzyme for the formation of hemoglobin as well as amino acid and protein metabolism.
A dilated fundus exam reveals white crystalline deposits within the macular region of your patient. Which of the following medications is MOST likely responsible for causing these deposits?
A. Amiodarone
B. Tamoxifen
C. Plaquenil®
D. Ciprofloxacin
B.
Explanation - Tamoxifen; is frequently used in the treatment of breast cancer. Patients taking this medication may experience decreased visual acuity due to white crystalline retinal deposits; these are most densely concentrated around the paramacular region. Tamoxifen; may also cause corneal deposits, cystoid macular edema, grey lesions within the RPE, retinal hemorrhages, and optic disc edema.
Plaquenil® is an anti-malarial drug that is frequently prescribed to treat systemic lupus and rheumatoid arthritis. The medication binds to melanin and accumulates in the retina, leading to macular mottling and retinal pigment epithelial disruptions and often resulting in what is known as “bull’s eye maculopathy”.
Amiodarone is an anti-arrhythmic medication. Use of this drug commonly causes yellow/brown or white powdery corneal epithelial deposits located infero-centrally that appear to swirl outward while sparing the limbus (vortex keratopathy).
Fluoroquinolones are a powerful class of antibiotics that inhibit bacterial DNA gyrase but, when taken orally, pose a risk of tendon rupture and tendinitis. The risk of the aforementioned side effects increases in individuals over the age of 60 or those with renal failure or taking oral steroids or in people who have undergone an organ transplant. Fluoroquinolone use also may be associated with diplopia.
Which of the following glaucoma medications causes lengthening and thickening of eyelashes as a side effect?
A. Dorzolamide (Trusopt®)
B. Brimonidine (Alphagan-P®)
C. Bimatoprost (Lumigan®)
D. Pilocarpine
C.
Explanation - Lumigan® is classified as a prostaglandin. This category of glaucoma medications can cause growth of eyelashes as a side effect along with pseudodendrites, photophobia, irritation, superficial punctate keratitis, cystoid macular edema, hyperemia and changes to iris color. By taking advantage of this desired cosmetic side effect, Latisse®, patented by Allergan, was created specifically for the purpose of promoting eyelash length and thickness.
Which 2 of the following statements are TRUE in regards to the ocular absorption of ophthalmic drugs? (Select 2)
A. The primary absorption pathway for small, lipophilic drugs is the transcorneal route
B. The primary absorption pathway for small, lipophilic drugs is the transconjunctival route
C. The primary absorption pathway for large, hydrophilic drugs is the transcorneal route
D. The primary absorption pathway for large, hydrophilic drugs is the transconjunctival route
A, D
Explanation - Topical instillation of medications is the most common method utilized to administer treatment for ocular conditions. There are two major pathways that allow an ophthalmic drug to enter the eye: the transcorneal route and the transconjunctival (conjunctiva-sclera-ciliary body) route. Various properties of the topical drugs will determine which pathway is used to permeate the ocular tissue barriers. The primary absorption route for small, lipophilic drugs is the transcorneal route, while the primary pathway for larger, hydrophilic drugs is the transconjunctival route.
Which of the following pain relievers is MOST LIKELY to cause liver damage and therefore should not be given to a person who suffers from liver disease?
A. Ibuprofen (Motrin®)
B. Acetylsalicylic acid (Aspirin)
C. Acetaminophen (Tylenol®)
D. Naproxen (Naprosyn®)
C.
Explanation - Tylenol® is an oral analgesic that works well for mild to moderate and acute or chronic pain without inhibiting platelet aggregation. Tylenol® is metabolized by the liver and excreted by the kidneys and therefore should not be recommended to people who suffer from liver impairment or chronic alcoholism. Aspirin is also a mild oral analgesic; however, unlike Tylenol®, it can prolong bleeding time as it interferes with platelet aggregation. Aspirin is contraindicated in people who suffer from upper gastrointestinal (GI) disease, asthma, nasal polyps, bleeding disorders or have chronic renal or hepatic disease. Motrin® and Naprosyn® are classified as nonsteroidal anti-inflammatory drugs (NSAIDS) and also work very well for mild to moderate pain relief. NSAIDS may cause GI irritation, mild inhibition of platelet aggregation, and kidney damage. Any of the above drugs can cause liver problems if used inappropriately; however, because it is primarily metabolized by the liver, Tylenol® does have a greater propensity to cause liver damage.
Which of the following is a common side effect of oral administration of erythromycin?
A. Weight gain
B. Gastrointestinal upset
C. Tinnitus
D. Otitis media
B.
Explanation - Many patients who take erythromycin experience GI upset; it is advised that this medicine be taken either 1 hour before or two hours after a meal. Erythromycin has not been known to cause weight gain or tinnitus, nor has erythromycin been linked to otitis media. It is noteworthy that aspirin use has been associated with tinnitus.
Which of the following cycloplegic/mydriatic ophthalmic drops is CONTRAINDICATED in children with Down’s syndrome (Trisomy 21)?
A. 1% Atropine
B. 1% Tropicamide
C. 1% Cyclopentolate
D. 2.5% Phenylephrine
A.
Explanation - Atropine is a useful ophthalmic drop that is available in 0.5%, 1% and 2% concentrations. Its cycloplegic effect can last for as long as 12 days. It is commonly utilized for cycloplegic refractions in children, treatment of uveitis, amblyopia, and to test for glaucoma by inducing acute angle-closure glaucoma (verifies if angles are open). Its ocular side effects include irritation, contact dermatitis, elevation of intraocular pressure (IOP), and angle-closure glaucoma. Atropine is contraindicated in people who have narrow angle glaucoma and open angle glaucoma because it can cause an increase in IOP. Atropine should also not be used in children with Down’s syndrome because it leads to a hyper-sensitive reaction where the extent of the mydriasis is greater than that of normals. Although some articles currently exist that refute the argument that atropine is not safe to use in people with Down’s syndrome, it is ALWAYS best to exercise caution in the best interests of the patient. There are many other cycloplegic agents that can be used as alternatives without posing a risk to patients with Trisomy 21. Bear in mind that homatropine and scopolamine carry the same contraindications as atropine.
