Pregnant or breastfeeding women, older patients and other patients with certain medical problems are advised to first consult their doctors before using the drugs. These medical problems are heart disease, heart rhythm problems, severe lung disease, kidney disease, liver disease, and thyroid disease (Flanigan).
Although side effects of digitalis drugs are rare, patients are urged to consult reactions such as skin rash, hives or other troublesome symptoms (May 2006). Signs of overdose should be observed and also reported promptly. Digitalis drugs may also interact with other medicines and side effects can develop. They may increase the risk of heart rhythm disorders when taken with other heart medicines, amphetamines or diet medicines. Taking calcium channel blockers may increase digitalis level and lead to overdose. Diuretics, which reduce the amount of potassium in the body, may increase the side effects of digitalis medicines. Anti-diarrhea or cholesterol medicines and high-fiber foods can prevent the absorption of digitalis drugs. Digitalis drugs should be taken and high-fiber foods eaten several hours before taking any drugs, which interact with them (May).
Digitalis can also be toxic or poisonous. Reports say that in the U.S., approximately.4% of all hospital admissions, 1.1% of outpatients using digoxin and 10-18% of home patients develop toxicity (Schreiber et al. 2006, Perez 2001). Globally, toxicity has been reported in 2.1% of inpatients on the drug and 0.3% of all hospital admissions. Usual morbidity at 4.6-10% rises to 50% if the digoxin is taken at doses higher than 6 mg/mL. Mortality is variable. Older persons are more affected than younger ones and adults, more than children. Advanced age of 80 or more is a risk factor to both morbidity and mortality. The overall incidence has, however, been lowered on account of certain factors. These include increased awareness of drug reactions by doctors, patients and the general public; reduced use of digoxin in treating heart failure and arrhythmias and the use or radio-immunoassays to monitor drug levels (Perez, Schreiber et al.).
Physicians first recognized and studied digoxin toxicity in 1785 (Schreiber et al. 2006). The effect of digoxin results from the inhibition of the sodium-potassion adenosine triphosphatase pmp. The role of calcium and sodium and the loss of intracellular potassium increases the force of muscular contraction of the heart. This bring about the net positive inotropic effect of digoxin. Digoxin also increases the automaticity of Purkinje fibers but slows down conduction. Dysrhythmias sometimes occur with an increase in automaticity, resulting in a decrease in conduction. Cardiac glycoside toxicity from plants, is rare but quite deadly (Schreiber et al.).
Digitalis toxicity is considered a complication of digitalis therapy or incorrect ingestion of digitalis (Perez 2001). It can result from high levels of the drug in the body or the body's decreased tolerance to the drug. Toxicity can result from a single exposure or long-standing overmedication. It may also occur even with normal levels of the drug but due to interaction with certain other drugs. Patients with heart failure are prescribed with diuretics along with digitalis to eliminate excess body fluid. But some diuretics can lead to loss of potassium, which increases the risk of digitalis toxicity. Digitalis toxicity may also develop from reduced levels of magnesium in the body. Kidney problems may likewise increase the risk of digitalis toxicity (Perez).
Digitalis toxicity is diagnosed through an ECG, taking of the heart rate, the serum level, and blood chemistry, which reveals the potassium and magnesium levels (Perez 2001). Recent cases of digitalis toxicity are treated with gastric lavage and charcoal intake. Introduction of digoxin-specific antibodies may be resorted to in severe or emergency cases. Hemodialysis reduces digitalis levels in the body. Complications of digitalis toxicity include arrhythmias, lethal arrhythmias, and heart failure. It can be prevented by regular monitoring of digitalis levels through blood chemistries. Doctors prescribe potassium supplements when digitalis and diuretics are simultaneously taken (Perez).
Angiotension-Converting Enzyme or ACE Inhibitors
ACE inhibitors help relax blood vessels by preventing an enzyme from producing angiotensin II (Mayo Clinic Staff 2006). Angiotensin Ii is a substance, which narrows blood vessels. Narrowing can result in high blood pressure and force the heart to work harder. There are many ACE inhibitorsavailable for different conditions. Examples are benazepril, enalapril, and lisinopril. ACE inhibitors prevent, treat or improve the symptoms of high blood pressure, coronary artery disease, heart failure, diabetes, some chronic kidney diseases, heart attacks, scleroderma and migraines. Known side effects of ACE inhibitors are dry cough, increased blood-potassium level, rash, dizziness, lightheadedness, changes in taste and decreased appetite. Pregnant women or those planning to become pregnant have been cautioned about ACE inhibitors. They have been linked to birth defects (Mayo Clinic Staff).
By inhibiting angiotensin, ACE inhibitors widen blood vessels and thus increase the amount of blood pumped and reduce blood pressure (Weiss 2007). They are prescribed not only to regulate high blood pressure but also for heart attack prevention. A national survey reported that 2.7 million childbearing women received prescriptions for an ACE inhibitor. There were 150 million prescriptions in 2005 alone (Weiss).
Studies published in the New England Journal of Medicine found that ACE inhibitors could cause birth defects when taken in the first trimester of pregnancy (Weiss 2007, Hitti 2007). Earlier studies had already established the likelihood of birth defects during the second and third trimesters. The most common observed defects were those in the nervous system and in the heart. Associate professor of pediatrics William O. Cooper at the Vanderbilt University Schools of Medicine said that the action of ACE inhibitors on the angiotensin enzyme can interfere with the proper organ development of the fetus. The study gathered data on 29,507 infants born between 1995 and 2000. Of this number 856 were found to have birth defects with 203 showing more than one defect. Of the 18 exposed to the drug during the first trimester, roughly 7% were born with defects. These were defects in the heart, the muscles, the skeletal, gastrointestinal and central nervous systems (Weiss, Hitti).
The American College of Obstetrician and Gynecologists said that up to 5% of women already have high blood pressure before they become pregnant (Mayo Clinic Staff 2006, Hitti 2007). Diet and exercise are often sufficient to control the condition. In other cases, however, medication is needed and prescribed. They are advised to avoid ACE inhibitors and ARBs. Doctors will prescribe a safer medication with the lowest but effective dose. But these women who are already taking the medication are advised not to discontinue taking it or to adjust it (Mayo Clinic Staff, Hitti).
But on the whole, ACE inhibitors offer greater protection against coronary heart disease than angiotensin receptor blockers or ARBs (Science Daily 2007). This was the conclusion of a new research published in the Journal of Hypertension by the George Institute for International Health. ACE inhibitors and ARBs are among the drugs, which lower blood pressure. The research evaluated the benefits derived from these two drugs. It was found that ACE inhibitors reduced the risk of coronary heart disease 9% better than ARBs. The finding would be a valuable input for half a million people diagnosed with high blood pressure by their doctors each year. The results were obtained from data collected on more than 160,000 patients. These were important additional inputs to data already gathered by the Blood Pressure Lowering Treatment Tialists' Collaboration. The group is known to have undertaken extensive research on the benefits of blood-pressure lowering drugs. It also found that aggressive treatment, which can bring blood pressure lower than target levels can provide even greater protection against stroke, coronary heart disease and other complications. The George Institute for International Health organized the Collaboration in 1995 to provide clinicians and policymakers with the best available evidence on the effects of various blood pressure drugs and medications (Science Daily).
Meanwhile, a study conducted found that ACE inhibitors do not lower the risk of cardiovascular death, heart attack or the need for bypass surgery or angioplasty (NHLBI 2004). It elaborated that many heart patients presently on modern therapy do not necessarily benefit from ACE inhibitors. This new study was funded by the National Heart, Lung and Blood Institute of the National Institutes of Health. Currently, the American Heart Association recommends the use of ACE inhibitors by all patients who have had a heart attack and coronary and other vascular diseases. Established clinical studies maintained that ACE inhibitors improve survival and reduce the risk of heart attack among those who sustain heart failure. Ace inhibitors have also shown to help prevent heart failure in those with moderate to severe ventricular dysfunction or lower chamber abnormalities. Acting Director Barbara Alving said that this new finding would significantly change clinical care of millions of Americans with heart disease. Heart disease is the single leading cause of death in the U.S., with more than 13 million adults diagnosed with a coronary heart disease. This puts them at risk for heart attack, sudden death, angina, heart failure and stroke (NHLBI).