+ Intravenous infusion of 0.4 - 1.2g mixed in 250 - 500ml of 5% glucose solution, at a dose of 5 - 10mcg/minute
+ Cardiac arrest: inject 0.4mg directly into the heart. 1ml tube = 0.2mg; 0.5mg or 5ml = 1mg. Lozenge: 10mg
Tablets: 30mg
2.1.1.2. Dobutamine
Effect (selective on 1 )
+ Increases myocardial contractility and cardiac output, but the drug only increases heart rate very slightly, thereby increasing the myocardial oxygen demand slightly.
+ Reduces peripheral resistance and pulmonary capillary pressure
Assign
+ Cardiogenic shock, especially after heart surgery with extracorporeal circulation
+ Severe, uncompensated heart failure that does not respond to other treatments
How to use and dosage
Intravenous infusion at a rate of 2 - 15mcg/kg/min, adjusting the dose according to the patient's condition until the effect is achieved (maximum 40mcg/kg/min)., t/2 is 2 - 3 minutes. Dissolve the drug in 5% glucose solution or 0.9% sodium chloride, do not mix in alkaline solution.
Vial of lyophilized powder 250mg dobutamine base, 20ml vial = 250mg
2.1.2. Phosphodiesterase inhibitors
2.1.2.1. Biperidine derivatives
Includes amrinone (inocor) and milrinone (primacor)
Effect : increases heart contraction, increases cardiac output. Dilates blood vessels, thereby reducing preload and afterload.
Unwanted effects : fever, headache, digestive disorders, loss of taste, thrombocytopenia... will disappear when stopping the drug
Indication : acute heart failure (only for inpatients with continuous hemodynamic monitoring)
How to use and dosage
+ Amrinon : 20ml tube = 100mg amrinone lactate, mixed in 0.9% sodium chloride solution for daily use (do not mix in 5% glucose because of incompatibility). Slow intravenous injection of initial dose 0.5mcg/kg, then infuse at a rate of 2 - 20 mcg/kg/minute (maximum 10mg/kg/day), t/ 2 is 2 - 3 hours
+ Milrinone : 10 times stronger than amrinone. 10ml tube = 10mg, 20ml = 20mg. Injection
Intravenous undiluted or diluted drug solution. Loading dose 50mcg/kg (in 10 minutes), then infuse at a rate of 0.25 – 1mcg/kg/minute, t/2 is 30 – 60 minutes.
2.1.2.2. Benzimidazole derivatives : these drugs are currently being researched.
2.2. Other drugs
2.2.1. Spacstein
An alkaloid extracted from the laburnum plant, commonly used as spatein sulfate salt. Makes the heart beat stronger, more regular and slower.
Assign
+ Threat of cardiovascular collapse due to trauma, poisoning
+ Palpitations, stabbing pain in the heart area (not coronary syndrome)
+ Cardiac support between glycosides
+ Combined with morphine and scopolamine in pre-anesthesia
+ Induce labor: makes the uterus contract strongly and regularly
How to use and dosage
Oral or subcutaneous injection 0.05g/time, 1 - 3 times/day 1ml tube = 50mg, 100mg
Tablets: 50mg, 100mg
Now rarely used because of poor effect.
2.2.2. Camphor
Makes the heart beat strongly and evenly, stimulates breathing, causes sweating and lowers temperature
Indications: cardiovascular collapse, infection, poisoning
10% oil solution injected subcutaneously 2 – 5ml
10% water-soluble solution for subcutaneous injection 1-10ml. Rarely used now because of its weak effect.
2.2.3. Amino - 2 methyl- 6 heptaminol
Increases coronary artery output, cardiac output, diuretic and increases blood pressure. Less toxic, often used with digitalis to treat heart failure
Indications: cardiovascular collapse, cardiac complications during surgery, acute myocarditis, infection, myocardial infarction
Adults take 1 - 2 pills/time, 3 times a day, intravenous or intramuscular injection 5 - 10ml/time, 2 - 3 times a day. Children depending on age
Tablets: 0.1878g 150mg
2ml tube = 0.125g, 5ml = 0.313g
VALUATION
1. Describe the effects, mechanism of action, indications, contraindications and dosage of Digitoxin, Digoxin and Uabain?
2. Describe the effects, indications, contraindications and dosage of Biperidin and Spactein derivatives?
HYPERTENSION MEDICATION
Target:
1. Describe the groups of drugs used to treat high blood pressure and the blood pressure lowering mechanism of each group of drugs.
2. Describe the effects, side effects and therapeutic applications of some commonly used drugs in each group.
3. Present the principles of treatment of essential hypertension
1. General
1.1. Definition
According to the World Health Organization, a person is diagnosed with high blood pressure when systolic blood pressure ≥ 140mmHg and/or diastolic blood pressure ≥ 90 mmHg
1.2. Grading of hypertension
Table 1: Classification of normal blood pressure in adults
BP measured after 5 minutes of rest
rest
Systolic BP (mmHg) | Diastolic blood pressure (mmHg) |
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< 120 and | <80 | |
Optimal normal HA | 120 - 129 and | 80 - 84 |
Normal high BP | 130 - 139 and | 85 - 89 |
Minimum normal HA
Table 2: Classification of high blood pressure (BP) in adults
BP measured after 5 minutes of rest
rest
Systolic BP | diastolic blood pressure | |
Mild HAT - grade 1 | 140 - 159 | and/or 90- 99 |
Moderate HAT - level 2 | 160 - 179 | and/or 100 - 109 |
Severe HAT - grade 3 | ≥ 180 | and/or 110 |
Isolated systolic HAT | ≥ 140 and | and < 90 |
1.3. Classification of hypertension
– Classification by degree: As above table
– Classification by cause
+ Primary hypertension: no cause of high blood pressure can be found, then it is called hypertension.
+ Secondary hypertension: high blood pressure is only a symptom of diseases in other organs (acute or chronic nephritis, Cushing's syndrome, hypercalcemia, aortic stenosis), this type accounts for 11 - 15% of all cases of hypertension.
1.4. Pathogenesis of primary hypertension
The two basic factors that determine blood pressure are cardiac output and peripheral resistance. These two factors depend on many other factors, namely: the activity of the nervous system, adrenal cortex and medulla, ADH hormone, muscle condition, vascular wall, salt balance, specifically:
+ Cardiac output is affected by stroke volume and heart rate (heart rate), while stroke volume depends on myocardial contractility and heart rate.
Myocardial contractility: the heart contracts strongly, stroke volume increases and cardiac output increases, blood pressure increases.
Heart rate: heart beats slowly, stroke volume does not increase and cardiac output decreases, blood pressure decreases. Heart beats fast, stroke volume does not increase, but cardiac output still increases, blood pressure increases. However, when the heart beats > 140 times/minute short diastole, blood does not return to the heart in time, stroke volume decreases and cardiac output decreases, so blood pressure decreases.
+ Mechanism of increasing cardiac output and increasing peripheral vascular resistance
When the amount of Na + entering the body is higher than the amount of Na + excreted increases circulating fluid volume, increases cardiac output.
Renin-angiotensin system: this system plays a major role in regulating blood pressure and sodium balance. In essential hypertension, there is always an increased activity of this system leading to:
• Causes rapid and strong constriction of arterioles and veins, increasing peripheral resistance. Venoconstriction also causes more blood to return to the heart (increasing cardiac output).
• Reduces salt and water excretion (retains Na + ), increases circulating volume,
increased cardiac output, increased blood pressure.
The role of stress: stress (psychological) directly stimulates the sympathetic nerves secretes catecholamine, increases the heart's contractility, increases heart rate (ie increases cardiac output). Catecholamine also causes constriction of efferent arterioles and hypertrophy of blood vessel walls increases peripheral resistance.
An important factor in high blood pressure is narrowing of the small arteries and capillaries, in most cases the cause is not found. Therefore, drugs must be used to act on the stages of the blood pressure regulation mechanism to dilate blood vessels, reduce cardiac output, leading to lower blood pressure (see figure).
* All drugs used to treat high blood pressure are symptomatic drugs (some drugs are presented in the related article section)
Self-regulating
Blood pressure p =
Cardiac output
Peripheral vascular resistance
systolic
Contraction
Hypertrophy
Deposit
Sympathetic
V cheek increased
Stress
The story
Frequency
D plating heart
Hypertension
Increase in income
Na +
Kidney retention
Na +
Renin
angiotensin
Factors of blood pressure and mechanisms of hypertension
2. Drugs for treating high blood pressure
2.1. Classification
Based on the location or mechanism of action, drugs are divided into the following 5 types:
Diuretics (reduce circulating volume): see diuretics
Sympatholytic drugs.
+ Central - destroying drugs
+ Ganglione blockers Reduce heart rate and reduce peripheral vascular resistance
+ β- blockers (See autonomic nervous system article)
+ - destroying drugs
Direct vasodilators
+ Arterial dilators
+ Arterial and venous dilators
Calcium channel blockers
Angiotensin converting enzyme inhibitors
This article only introduces drugs that have not been mentioned in previous articles.
2.2. Calcium channel blockers
2.2.1. Physiological role of Ca ++ on the cardiovascular system
In the heart muscle, Ca ++ binds to troponin, eliminating the inhibitory effect of troponin on contractile function, so actin filaments can interact with myosin to cause heart muscle contraction.
On vascular smooth muscle, when intracellular Ca ++ increases, it will form a complex with calmodulin, this complex activates protein - kinase, promoting the interaction between actin and myosin causing contraction of vascular smooth muscle.
2.2.2. Pharmacokinetics : absorbed orally and metabolized first-pass through the liver. Currently, functional groups in the formula have been changed to slow down drug metabolism. Therefore, 1st, 2nd, and 3rd generation drugs have been created.
2.2.3. Mechanism of action : the drugs bind mainly to calcium channels (L channels are abundant in the heart muscle and vascular smooth muscle) to block calcium channels, inhibit Ca ++ from entering heart muscle cells and vascular smooth muscle cells dilates blood vessels and lowers blood pressure.
2.2.4. Effects on organs
On smooth muscle: relaxes smooth muscle of the airways - bronchi, digestive tract, uterus, especially smooth muscle of vascular walls (arterial capillaries are more sensitive than venous capillaries).
On the heart muscle: reduces impulse generation, reduces conduction and reduces myocardial contraction reduces myocardial oxygen demand, so it should be used to treat angina (especially due to coronary spasm).
Cerebral vessels: nimodipine has high affinity for cerebral vessels, used for patients with cerebrovascular accidents such as subarachnoid hemorrhage (but the result is due to cerebral vasodilation or reduced oxygen demand of neurons is unclear).
2.2.5. Undesirable effects
Mild: hot flashes, headache, dizziness (due to vasodilation reflex, increased heart rate), nausea, constipation.
More severe: slow heartbeat, atrioventricular block, congestive heart failure, cardiac arrest..., due to strong inhibition of Ca ++ channels (rare).
2.2.6. Indication
Treatment of hypertension (currently considered a safe and effective group of drugs for patients)
Treatment of localized angina (due to coronary spasm), this is the main mechanism of angina.
Due to the effect of reducing atrioventricular conduction, verapamil and diltiazem are also indicated in supraventricular tachyarrhythmias.
2.2.7. Preparation and dosage
Nifedipine
Tablets: 5mg, 10mg, 20mg,
Extended-release tablets 30mg, 60mg and 90mg
Treatment of hypertension and Raynaud's syndrome: take 10-20mg 3 times a day, every 6-8 hours.
Prevention of angina pectoris: use long-acting tablets 10 - 40 mg/day divided into 2 doses. Maximum 60 mg/day
Diltiazem
Tablets: 60mg
Capsules: 60mg 90mg, 120mg, 180mg, 240mg, 300 mg Extended-release tablets: 60mg, 90mg, 120 mg
Take 60mg/time, 3 times a day (before meals for better absorption)
Treatment of hypertension: take slow-release tablets 60 - 120 mg/day divided into 2 doses, increase dose every 14 days if needed. Maximum 360 mg/day.
Verapamil.
Coated tablets: 40mg, 80mg, 120 mg
Extended-release tablets: 120mg, 180mg, 240mg. Syringe: 2ml = 5mg; 4ml = 10mg.
Treatment of high blood pressure: take 80mg/time, 3 times/day
Treatment of angina pectoris: take 80 - 120mg/time, 3 times a day. Extended-release tablets: take 180mg/day, swallow without chewing.
Felodipine.
Take 5 - 10 mg/day divided into 2 times, maximum 20 mg/day. People with liver or kidney failure or the elderly take 5 mg/day. Tablets: 5 mg, 10 mg.
Nicardipine
Capsules: 20mg, 30mg
Extended-release capsules: 30mg, 40mg, 45mg, 60mg Tablets: 20mg
Injection: 2.5 mg/1ml
Treatment of hypertension and angina pectoris: 30 mg/time, 3 times/day (maximum 60 mg)
- 120 mg/day). Slow intravenous infusion of 0.1 mg/ml solution for short-term treatment of hypertension, initial rate 5 mg/hour, if necessary can reach a dose of 15 mg/hour and then reduce to 3 mg/hour.
Nimodipine
Soft capsule: 30mg; Tablet: 30mg Injection vial 10mg/50ml.
Treatment after subarachnoid hemorrhage. Intravenous infusion through a catheter into the central vein, initial dose 0.5 - 1 mg/hour, then increase the dose according to the patient's response, use for 5 days and not more than 14 days. Switch to oral dose when the patient