Lotensin Review Article
Lotensin or benazepril hydrochloride is a prescription only antihypertensive drug belonging to the ACE inhibitors. It is also used for the treatment of congestive heart failure (Sweetman, 2009).
Lotensin is a nonsulfhydryl prodrug (Balfour and Goa, 1991), which means that upon administration, it is converted to its active metabolite. Specifically, the ester moiety of the drug is cleaved by the esterases found in the body, benazeprilat. This active metabolite is responsible for its antihypertensive action. The drug can be seen in the blood in as fast as one hour, reaching maximum activity within 2-4 hours. Though the maximal effect is felt in the said time, the full physiological effect may not develop for about two weeks (Sweetman, 2009). Mechanism of Action The renin-angiotensin-aldosterone system (RAAS) and ACE ACE Inhibitors such as Lotensin are drugs that act on ACE involved in the renin-angiotensin-aldosterone system (RAAS). Renin, the first enzyme involved, is released from the kidneys when there is a decrease in blood pressure in the body, as signaled by low perfusion or as signaled by the sympathetic nervous system (SNS).
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Renin activates angiotensinogen (which is released from the liver), converting it to the active enzyme angiotensin I. Angiotensin I is converted to the active agent, angiotensin II, resulting to various physiological effect (increased water retention and reabsorption via antidiuretic hormone or ADH, salt retention via aldosterone, vasoconstriction) which ultimately leads to blood pressure increase. The enzyme responsible for the conversion of angiotensinogen I to angiotensinogen II is ACE. Thus, the inhibition of ACE will result to the inhibition of angiotensin I to angiotensin II, leading to a decrease in blood pressure.
Several studies have indicated the efficacy of Lotensin in the treatment of hypertension and congestive heart failure. In a study made by Balfour and Goa (1991), they have found that a daily dose of 5 to 80 mg effectively control blood pressure to mild to moderately severe hypertensive patients. Furthermore, in this study, it was found that Lotensin have beneficial effects on cardiac function and improve exercise capacity and clinical symptoms for congestive heart failure patients.
Lotensin was observed by some studies to be acting by other mechanisms to reduce blood pressure. In a study by Pan and colleagues (1998), they found that Lotensin also acts on plasma fibrinogen and platelet aggregation (decreasing both parameters), providing better control for blood pressure. Plasma fibrinogen and platelet aggregation are factors affecting blood pressure. When there are high amounts of plasma fibrinogen accompanied by fast platelet aggragation formation, blood pressure can increase due to a decreased in the space in blood vessels. In a study by Giannattasio and colleagues, they found that Lotensin also acts by sympathomodulation, by deactivating cardiopulmunoary and arterial baroreceptors.
Comparing to other drugs belonging to the same class, Lotensin is atleast equivalent to captopril (the first in the class) and enalapril (Balfour and Goa, 1991). In a study made by Zadionchenko and colleagues, it was found that Lotensin has some advantages over Capoten: more potent in reducing ST expression (on ECG); and further improvement upon long term use.
Comparing to other drugs belonging to another class, Lotensin is again equivalent to hydrochlorothiazide, nifedipine, nitrendipine or propranolol (Balfour and Goa, 1991).
Hypertension (high blood pressure) is defined as a persistently elevated systolic blood pressure. It is the most common cardiovascular disease with around 600 million people around the world are hypertensive (according to the World Health Organization). In the United States, for example, it was found as the leading primary diagnoses made in the that country.
Hypertension is considered a serious medical condition. Though per se it is not deadly, the complications associated with it are. A sustained high blood pressure damages the blood vessels of the body from the kidneys, the heart, the brain which causes serious malfunction. According to The Joint National Committee 7th report on Prevention, Detection Evaluation and Treatment of High Blood Pressure, the risk of cardiovascular morbity and mortality is directly correlated with blood pressure as blood pressure increases, the risk for heart failure, heart attack, stroke, kidney diseases also increases. Several epidemiologic studies have been done to support this. Even mild hypertension in young adults has been found to increase the risk of end organ damage.
Aside from that, hypertension is sometimes referred to as the silent killer. This is because most people with hypertension do not know that they have the condition. Hypertension is usually asymptomatic in its early stages, and can only be detected upon regular check up. For example, according to one study, of all the hypertensive patients in the US, only about 70% are aware of that they have condition the other 30% are unaware. Most symptoms of hypertension appear when end organ damage has already occurred which is why it is deadly.
Because of the widespread occurrence and the serious threat of this disease, several international guidelines have been published to effectively manage and control blood pressure levels. Several studies have shown that reducing blood pressure levels within acceptable levels, as provided by the JNC 7th report, significantly reduces the risks of cardiovascular morbidities and mortalities. With that said, the goal of hypertensive therapy, therefore, is to reduce the occurrence of these complications. Aside from lifestyle modifications (recommended for all stages of hypertension) which include serious weight reduction, better diet control such as salt and alcohol restriction, and increased physical activity, antihypertensive drugs are recommended for use. Several drugs are available for the management of this condition, which may belong to either one of the four mechanisms for control the diuretics which decreases blood volume; sympathoplegic agents which reduces vascular resistance thus reducing the necessary force for blood flow; direct vasodilators which relaxes smooth muscles and dilates them, and lastly, the those that act on angiotensin, which acts via a cascade of mechanisms dealing with the said enzyme. Two drug class belong to the fourth category, the first being the angiotensin converting enzyme inhibitors or ACE inhibitors. Lotensin, or benazepril, belongs to this drug class.
Combination therapy: Amlodipine
Several studies have shown the efficacy of amlodipine and lotensin combination. Studies made by Pool and colleagues (2001), Kuschnir and colleagues, Messerli, Weir and Neutel (2002), Jamerson and colleagues (2008) have all shown that a combination of the two drugs as compared to monotherapy of either drug is superior and well tolerated by patients.
For the treatment of hypertension, Lotensin is initially administered at a dose of 10mg once daily. For patients with renal impairment, a half strength dose is used. The maintenance dose is about 20-40mg per day, reaching a maximum of 80mg per day.
When used for congestive heart failure, the initial dose is 2.5mg once daily, up to a maximum of 20mg per day.
Lotensin action lasts for 24 hours, allowing for once a day administration. It is available in 5, 10, 20 and 40mg tablets.
In a study made by Palatini and colleagues (1993), they have concluded that Lotensin is preferably taken in the morning because of better coverage of 24 hours, as measured in a continuous intraarterial monitoring.
Lotensins adverse effects are related to its pharmacologic action. This includes hypotension (most pronounced in the initial therapy), dizziness, fatigue, headache, nausea, decreased renal function, possible blood disorders (neutropenia, agranulocytosis, thrombocytopenia, anemia) and gastrointestinal problems (Sweetman, 2009). Because of renal adverse effects, it is recommended to monitor renal function before and throughout the use of the drug. It is recommended to reduce the dose when creatinine clearance is less than 30ml per minute (Kaiser, Ackermann and Sioufi, 2004).
Dry cough, upper respiratory tract symptoms, angioedema are symptoms associated with bradykinin. Bradykinin is an enzyme that is metabolized by ACE. When ACE is inhibited (as such with Lotensin), bradykinin remains active, causing the said adverse effects. All these side effects are reversible.
Lotensin is contraindicated in patients with aortic stenosis. ACE inhibitors belong to the Preganancy Category D, per US Food and Drug Administration. There is high evidence for fetal toxicity, as such, it is contraindicated for pregnant and breast feeding women.
Lotensin has been found to have an interaction with the following drugs:
Diuretics and other hypertensive agents
For full information, consult with the healthcare provider.
Balfour, J. A., and Goa, K. L., 1991, Benazepril. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy in hypertension and congestive heart failure
Health Grades Inc., Prevalence and incidence of hypertension
Giannattasio, C., Cattaneo, B. M., Omboni, S., et al., 1992, Sympathomoderating influence of benazepril in essential hypertension
Kaiser, G., Ackermann, R., Sioufi, A., 2004, Pharmacokinetics of a new angiotensin-converting enzyme inhibitor, benazepril hydrochloride, in special populations
Kuschnir, E., Acuna, E., Sevilla, D., et al., Treatment of patients with essential hypertension: amlodipine 5 mg/benazepril 20 mg compared with amlodipine 5 mg, benazepril 20 mg, and placebo
Merck Manual, Overview of hypertension
Messerli, F. H., Weir, M. R., Neutel, J. M., 2002, Combination therapy of amlodipine/benazepril versus monotherapy of amlodipine in a practice-based setting
National Heart, Lung and Blood Institute, 2004, The seventh report of the Joint National Committee on prevention, detection, evaluation and treatment of high blood pressure
Palatini, P., Mos, L., Motolese, M., et al., Effect of evening versus morning benazepril on 24-hour blood pressure: a comparative study with continuous intraarterial monitoring
Pan, R., Sun, M., Zhou, H., and Jia, Z., Effects of lotensin and nitrendipine on plasma fibrinogen and platelet aggregation in hypertensive patients
Pool, J., Kaihlanen, P., Lewis, G., et al., Once-daily treatment of patients with hypertension : a placebo-controlled study of amlodipine and benazepril vs amlodipine or benazepril alone
Sweetman, S. C. ed., 2009, Martindale, The complete drug reference 36th ed, London: Pharmaceutical Press, 1238
Zadionchenko, V. S., Timofeeva, Nlu, Li., V. V., and Suvorova, S. S., 2003, Comparative effectiveness of lotensin and capoten in patients with chronic cardiac failure
Lotensin Review Article