الحلقة 12 من كورس كلنيكال فارما في جزء (ANS)

Dobutamine (Dobutrex®)

- Dobutamine is a synthetie catecholamine.

- It is a predominantly β1 receptor agonist→ ↑ HR & CO with few vascular effects.

- Major advantage of dobutamine over other sympathomimetic drugs → it increases

cardiac output and does not significantly elevate oxygen demands of the

myocardium.

- Uses: Acute heart failure such as which occurs during cardiac surgery or in cases of

septic or cardiogenic shock (+ve inotropic effect).

- Adverse effects: hypertension, tachycardia, phlebitis (reactions at sites of IV

infusion), nausea, headache and anginal pain

- N.B: used with caution in atrial fibrillation, because it increases AV conduction

Xamoterol Prenalterol Denopamine

- All of these drugs cardiac stimulant.

Mechanism of

Action

In general activation of B2-adrenergic receptors :-

- Smooth muscles; Bronchodilatation and uterine muscle relaxation.

-Skeletal Muscles: Vasodilatation effect.

- Mast cells; decrease release of mediators (such as histamine) of

immediate hypersensitivity from mast cells (histamine).

- Liver; glycogenolysis (particularly if used in high doses).

Therapeutic

Uses

They are primarily used to treat bronchial asthma and other Disease

(COPD). pulmonary disorders such as Chronic Obstructive Pulmonary

Other specified uses:

- Ritodrine used in control of premature labor.

- Salbutamol may be used in treatment emergency hyperkalemia.

Routes of

Administration

- The choice of route of administration and drug to use depends on the

desired clinical effect.

- Inhaled route produces at least as much bronchodilation as oral or

parenteral therapy and does so with substantially fewer side effects.

Side

effects

- Tachycardia (palpitations); especially in parenteral administration.

- Tremor, especially in oral and parenteral administration.

-Insomnia, anxiety, dizziness, headache and nervousness.

Selective Adrenoceptor Agonist

Selective β1-adrenoceptor Agonist

Selective β2-adrenoceptor Agonists (BAA)

Short-acting Beta2-adrenoceptor Agonists (SABA)

- SABA used mainly 3-4 times daily.

Metaproterenol or Orciprenaline (Alupent®)

- Metaproterenol is a short acting B2 agonist.

- It is structurally and pharmacologically similar to isoproterenol.

- It is not metabolized by catechol-O-methyltransferase (COMT).

-Adult dose :-

Oral: 20 mg 3 to 4 times a day.

Inhalation aerosol: 2 to 3 inhalations every 3 to 4 hours, up to 12 inhalations/day.

Salbutamol or Albuterol (Ventolin®)

Adult dose:

- Oral: 2 to 4 mg orally 3 to 4 times a day.

- Metered-dose inhaler: 2 puffs every 4 to 6 hours.

- Inhalation capsules: 200 mcg inhaled every 4 to 6 hours.

Therapeutic Uses:

- Bronchospasm.

- Chronic obstructive pulmonary disease (COPD).

- Other Uses:

- Acute hyperkalemia (1 K+ to flow in cells thus level in the blood).

- Off-Label Uses: (Not approved by the FDA),But: Clenbuterol more preferred for this purposes

1.Bodybuilding and animal feeding:

2.Fat burning (lipolysis) and muscle gain (protein synthesis).

3.Doping: ↑ performance in healthy athletes.

Terbutaline (Bricanyl®(

Dose:

- Oral: 2.5 to 5 mg 3 times daily.

- SC: 0.25 mg as a single dose, May repeat in 15 to 30 min. (max. 0.5 as a total dose in 4 h).

Therapeutic Uses: Bronchospasm

- Off-Label Uses: (Not approved by the FDA)

- Preterm Labor: Brethine (Terbutaline) is one of the most frequently used drugs in the treatment of

preterm labor.

Subcutaneous dose is 0.25 mg every 20 to 60 minutes until a woman's contractions have subsided.

- Priapism (persistent penile erection):

Oral Terbutaline used in patients with prolonged erections of less than 4-hours duration, by relaxation

of the stretched corporeal smooth muscles

FDA warning Terbutaline should not be used to treat prolonged (more than 48 to 72 hours)

premature labor FDA pregnancy category C.

Long-acting Beta2-adrenoceptor Agonists (LABA)

- LABA used mainly 2 times daily (should not be used to treat acute symptoms).

Formoterol (Foradil®) Salmeterol (Serevent®)

- Formoterol , Salmeterol are long acting B2 agonist.

- Duration of action: extended up to 12 hours.

Treatment of Asthma:

- LABA must be used in asthma in combination with another long- term asthma-control medicine

(e.g. inhaled corticosteroids such as fluticasone and budesonide).

- Symbicort® → (Budesonide + Formoterol)

- Advair® → (Fluticasone + Salmeterol)

- Chronic obstructive pulmonary disease (COPD), may be used as mono-therapy or in combination

with corticosteroids.

- Before exercise: - LABA may be used before exercise to prevent exercise-induced bronchospasm

(EIB).

FDA Warning

- LABA have been shown to increase the risk of asthma-related death in pediatric and teenager

patients.

- LABA should not be used as a mono-therapy in the treatment of asthma to minimize serious

reactions such as asthma related deaths.

Contraindication

- Treatment of asthma without use of a long-term asthma control medication such as an inhaled

corticosteroid.

Clenbuterol (Spiropent®)

-Clenbuterol is a long acting B2 agonist.

- Effect of B-adrenoceptor agonists in body metabolism (Clenbuterol more potent) → Increase Fat

burning (lipolysis) and increase muscle gain (protein synthesis).

-Human Use:

Therapeutic Use (rare): Asthma and COPD. performance in athletes.

Off-Labd Uses: Bodybuilding, weight-loss and enhance

- Veterinary Use:

Therapeutic Use as bronchodilator in horses.

Animal Production: Clenbuterol (Ventipulmin®), Zilpaterol (Zilmax®) and Ractopamine (Optaflexx®)

are B2-adrenergic agonists widely used for increase the size of animals and the efficiency of feeding

them.

Levosalbutamol or Levalbuterol (Xopenex)

- Levosalbutamol is the R-enantiomer of salbutamol.

- Comparison to salbutamol;

- It has similar therapeutic effects.

- No benefit of levosalbutamol compared to salbutamol (systematic review in 2013).

Pirbuterol (Maxair®)

- Pirbuterol is a short acting B2 agonist used in asthma and COPD.

Ritodrine (Yutopar®)

- Ritodrine [RIT-oh-dreen] is a tocolytic drug, used to stop premature

Ultra-long-acting Beta2-adrenoceptor Agonists (Ultra-LABA)

- Ultra-LABA used mainly 1 times daily.

Indacaterol (Onbrez®)

- Indacaterol is an ultra-long acting B2 agonist.

- Indicated for long-term control of chronic obstructive pulmonary disease (COPD) symptoms.

- Used once daily at the same time of day.

- FDA warning Asthma-related death (Contraindicated in patients with acute asthma without use

inhaled corticosteroids).

Mirabegron (Myrbetriq®)

- Mirabegron is a B3 agonist.

- It is activate the B3 adrenergic receptor in the detrusor muscle in the bladder, which leads to muscle

relaxation and an increase in bladder capacity.

- It is used for patients with overactive bladder (OAB).

- Adverse effect :- increase blood pressure and should not be used in patients with uncontrolled

hypertension.

Fenoldopam (Corlopam®)

- Fenoldopam is an agonist of peripheral dopamine D1 receptors.

- It is a racemic mixture and the R-isomer is the active component.

Routes of administration: For continuous IV infusion only due to extensive first-pass metabolism and

short half-life elimination (10 minutes).

- Period of administration: up to 48 hours in adults

up to 4 hours in pediatric.

- Mechanism of action: Rapid-acting vasodilator→ agonist of peripheral dopamine D1 receptors→

VD of renal blood vessels → diuresis.

- Uses: Treat severe hypertension in hospitalized patients.

- Adverse effects: Headache, flushing, dizziness, nausea and tachycardia (due to vasodilation).

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