Article Date: 8/1/2004

therapeutic topics
Keeping Up with Side Effects from Hypertension Therapies
BY JULIE A. SCHORNACK, OD, MED, FAAO

Recent times have demonstrated a more aggressive approach from the medical community toward treating hypertension. Physicians in the past initiated treatment at later and more advanced stages of blood pressure elevation. In addition, the past front line of defense rested on the shoulders of diuretics and beta blockers. Although the armamentarium of treatment still includes these medications, several other categories of drugs are available to treat hypertension.

ACE in the Hole

Many doctors are moving toward using ACE Inhibitors, which are competitive inhibitors of angiotensin 1 converting enzyme (ACE). This enzyme converts angiotensin 1 into angiotensin 2, a powerful vasoconstrictor in the system. Examples of ACE Inhibitors are captopril (Capoten), enalapril maleate (Vasotec) and ramipril (Altace).

Patients typically experience few side effects from ACE Inhibitors. The most common systemic side effect is a dry cough that dissipates shortly after cessation of the drug. The only ocular side effect that may be associated with ACE Inhibitors is a generalized complaint of blurred vision.

A More Recent Option

A newer entry into the anti-hypertensive market is the angiotensin 2 receptor blockers (ARBs), which don't cause the dry cough side effect that so often accompanies ACE Inhibitors. ARBs include valsartan (Diovan) and losartan potassium (Cozaar), and they cause no appreciable ocular side effects.

Oldies -- But Not "Goodies"

Beta blockers and diuretics are the more classic anti-hypertension drug categories. Both may cause significant ocular side effects that could compromise comfort and success in lens wearers.

Beta blockers can cause decreased lacrimation, eyelid edema, loss of accommodation, ocular irritation and conjunctival dryness. Common beta blockers used for anti-hypertensive therapy include atenolol (Tenormin), betaxolol (Kerlone) and oxyprenolol (Trasicor).

Diuretic anti-hypertensive medications include hydrochlor-othiazide, furosemide (Lasix) and chlorothiazide (Diuril). Ocular side effects that diuretics may cause include decreased tear secretion that results in dry eye complaints and some transient myopia associated with specific diuretics.

Calcium Channel Blockers

The last anti-hypertensive drug category that I'll discuss includes the calcium channel blockers. Simplistically, they work by a resultant vasodilation and relaxing effect on contractility of the heart. Examples are nifedipine (Adalat), diltiazem (Cartiz XT), verapamil (Calan) and amlodipine (Norvasc). The most common ocular side effect of calcium channel blockers is eye pain.

Other Points to Consider

It's also important to remember that although physicians try to manage their hypertensive patients with the fewest possible number of effective drugs, it's not unusual to see multiple drug combinations to attain the desired target blood pressure. Consider the effects of such multi-drug therapies when determining the etiology of drug-induced ocular side effects.

You should investigate each drug if you suspect ocular side effects associated with prescribed medications. Specific drugs may produce more or fewer side effects when viewed in isolation. The ocular side effects that this article discusses can clearly affect contact lens wear. However, you should always educate your contact lens patient who takes medication for hypertension.

Dr. Schornack is the assistant dean of Clinical Education and serves in the Cornea and Contact Lens Service at the Southern California College of Optometry.

 


Contact Lens Spectrum, Issue: August 2004