Pharmacology 2060A/B Lecture 13: Module 13
15 May 2018
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Module 13 – Drugs for Hypertension
13.1 – Hypertension
- Hypertension is simply defined as elevated systemic arterial blood pressure
- Blood pressure is a measurement of the force against the walls of your arteries as the heart
pumps blood through the body
- Blood pressure is measured with a sphygmomanometer
- In order to accurately measure blood pressure:
o 1. The patient should be seated for at least 5 minutes
o 2. No caffeine or nicotine within 30 minutes of measurement
o 3. Feet should be touching the floor (not dangling)
o 4. Arm should be elevated to heart level
o 5. Two measurements in each arm should be taken 5 minutes apart
o 6. Before a diagnosis of hypertension, the patient should have this repeated 3 times at
least 2 weeks apart.
Blood pressure
- Blood pressure is classified by looking at the systolic and diastolic blood pressure
- Systole – When the heart contracts and pumps look out of the heart
- Diastole – Period of time when the heart fills after a contraction
- In clinical practice, blood pressure is read as the systolic pressure over the diastolic pressure
- For example, John’s BP is 120/80 would mean John has a systolic blood pressure of 120 mmHg
and a diastolic blood pressure of 80 mmHg
- Patients can be classified based on their blood pressure
- KNOW THE TABLE!!!
Types of hypertension
Primary hypertension
- Hypertension of no known cause
- Approximately 92% of all cases of hypertension → majority of patients
- 90% of people over the age of 55 have high blood pressure → common in elderly
Secondary hypertension
- Hypertension with an identifiable cause
- Causes include:
o 1. Kidney disease
o 2. Hyperthyroidism
o 3. Pregnancy
o 4. Erythropoietin
o 5. Pheochromocytoma – tumour on the adrenal gland that causes excess epinephrine
release (vasoconstriction = hypertension)
o 6. Sleep apnea
o 7. Contraceptive use
Causes of hypertension
- Many factors influence blood pressure including:
o 1. Amount of salt and water in body
o 2. Conditions of kidneys, nervous system and blood vessels
o 3. Level of certain hormones in body
- Risk factors for developing hypertension:
o Obesity, stress, smoking, high salt diet, diabetes, African descent (more severe
hypertension than Caucasians and Asians)
- Certain medications are known to cause hypertension including NSAIDS, oral contraceptives and
cold medications that contain pseudoephedrine
Consequences of hypertension
- Chronic hypertension is associated with increased morbidity and mortality
- If untreated, hypertension can cause myocardial infarction (heart attacks), kidney failure, stroke
or retinal damage
- Unfortunately, hypertension is a “silent killer” as many patients may have elevated blood
pressure for years before they show any symptoms
Why lower blood pressure?
- This one is easy! Lowering blood pressure saves lives
- Clinical trials have conclusively demonstrated that decreasing blood pressure decreases patient
morbidity and mortality
- Lowering blood pressure decreases the incidence of stroke, myocardial infarction (heart attack)
and heart failure
- It is estimated that decreasing blood pressure by just 5 mmHg can reduce the risk of stroke and
heart attack by 20 – 35%
o Minor decrease in BP can have a large beneficial effect
Determinants of blood pressure
- Drugs targeting blood pressure influence cardiac output for peripheral resistance
- Blood pressure is determined by CO and TPR
Cardiac output
- Is determined by heart rate, heart contractility, blood volume and venous return
Document Summary
Hypertension is simply defined as elevated systemic arterial blood pressure. Blood pressure is a measurement of the force against the walls of your arteries as the heart pumps blood through the body. Blood pressure is measured with a sphygmomanometer. In order to accurately measure blood pressure: 1. The patient should be seated for at least 5 minutes: 2. No caffeine or nicotine within 30 minutes of measurement: 3. Feet should be touching the floor (not dangling: 4. Arm should be elevated to heart level: 5. Two measurements in each arm should be taken 5 minutes apart: 6. Before a diagnosis of hypertension, the patient should have this repeated 3 times at least 2 weeks apart. Systole when the heart contracts and pumps look out of the heart. Blood pressure is classified by looking at the systolic and diastolic blood pressure. Diastole period of time when the heart fills after a contraction.
