Year 4 Medical Pharmacology Therapeutic

Case 1ABC, a 16-year old girl presented with difficulty in breathing and coughing progressively worsened over the past 2 days◦ Symptoms preceded by sore throat, rhinorrhoea

and cough for 3 days

◦ History of cough on and off, went to GP and was given cough medication.

On examination◦ Dyspnoeic, wheezing+, able to speak in short

sentences

◦ BP 110/83 mmHg, PR 130/min, T- 37.8oC

◦ hyperinflated chest, intercostal recession+ Rhonci++ with decreased breath sound on the left side

Diagnosis?

◦ Acute exacerbation of bronchial asthma

Further history to ask?

◦ Recurrent night cough

◦ Family history of asthma

How do you assess asthma severity?

In your opinion how is her condition?

What is the drug of choice and why?

◦ Β2- receptor agonist (short acting)

◦ For fast relief

Why not use other bronchodilators such as aminophylline or ipratropium?

◦ Aminophylline is not as efficacious as SABA and has more risk for serious adverse effects than SABA

◦ Ipratropium is not as efficacious as SABA

What is the preferred route of administration?

◦ Nebulizer

◦ Combination with ipratroprium improve pulmonary function and reduce rate of hospitalization

Any role of corticosteroids?

◦ Antiinflammatory.

◦ Block the reaction to allergen and reduce airway hyperresponsiveness.

◦ Inhibit cytokine production, adhesion protein activation and inflammatory cell migration and activation.

◦ Reverse β2 receptor downregulation.

◦ Inhibit microvascular leakage

What is the mode of administration for the patient?

◦ Oral vs parenteral

ABC responded well to treatment. She was discharged after 3 days in the ward

What advice you would give ABC before discharge?

What type of medication would you prescribe to ABC and why

SABA?

Corticosteroid inhaler?

Continue oral prednisolone for 5-7 days then off

Review?

Case 2

XYZ, a 45-year old man with a long history of persistent asthma went to A&E with complaint of severe SOB and wheezing.

Able to speak two or three words without taking a breath.

On inhaler beclomethasone 4 puff (80mcg/puff) bd, salbutamol prn.

Ran out of beclomethasone 1 week ago, been taking salbutamol only with increasing frequency upto every 3 hours on the day of admission

Case 2

On examination HR 130/min RR 30/min BP 130/90mmHG ABG under room air

◦ pH 7.4 (N 7.35-7.45)◦ PaO2 55mmHg (>80 mmHg)◦ PaCO2 40 mmHg (35-45 mmHg)

Comment the ABG results – normal or not normal??

Mild

pH

PaO2

PaCO2

HCO3-

Moderate

pH

PaO2

PaCO2

HCO3-

Severe*

pH

PaO2

PaCO2

HCO3-

* Beware the following:

• Speechless patient

• PEFR <50%

• Resp Rate >25

• Tachycardia >110 (pre 2 agonist)

ABG in Acute ASTHMA

Case 2ECG showed sinus tachycardia with

occasional premature ventricular contractions.

XYZ was given SC 0.5mg terbutaline with minimal improvement, O2 at 4L/min by nasal cannula.

Another SC 0.5mg terbutaline was then given. Subsequently his HR 145/min and he complained of palpitations and shakiness.

ABG pH 7.39, PaO2 60mmHg, PaCo2 42 mmHg

Summary of lab resuts Before terbutaline ABG

◦ pH 7.4◦ PaO2 55 mmHg◦ PaCO2 40 mmHg

BUSE◦ Na 140 mEq/L◦ K 4.1 mEq/L◦ Cl 105 mEq/L

After 2nd terbutaline ABG

◦ pH 7.39◦ PaO2 60◦ PaCO2 42

BUSE◦ Na 138◦ K 3.5

What adverse effects experienced by XYZ are consistent with systemic β2 agonist administration?

Case 2 ECG showed sinus tachycardia with

occasional premature ventricular contractions.

XYZ was given SC 0.5mg terbutaline with minimal improvement, O2 at 4L/min by nasal cannula.

Another SC 0.5mg terbutaline was then given. Subsequently his HR 145/min and he complained of palpitations and shakiness.

ABG pH 7.39, PaO2 60mmHg, PaCo2 42 mmHg

Β2 agonist are cardiac stimulants that may cause tachycardia and rarely arrhythmias

Summary of lab resuts Before terbutaline ABG

◦ pH 7.4◦ PaO2 55 mmHg◦ PaCO2 40 mmHg

BUSE◦ Na 140 mEq/L◦ K 4.1 mEq/L◦ Cl 105 mEq/L

After 2nd terbutaline ABG

◦ pH 7.39◦ PaO2 60◦ PaCO2 42

BUSE◦ Na 138◦ K 3.5

Decrease could be due to β2 adrenergic activation of Na+ K+ pump and subsequent transport of K intracellularly.

At usual doses, inhaler salbutamol or terbutaline cause relatively little effects on K, effect more noticeable with systemic administration.

That’s all,

Thank you

ASTHMA DRUGS

Bronchodilatation

↓ Inflammation

ß2 receptor Agonist

Salbutamol

MethylxanthinesTheophylline,aminophylline

AnticholinergicsIpratropium bromide

Mast cell stabilizersodium cromoglycate

CorticosteroidsBeclomethasone,

budesonide

Leukotriene pathway inhibitors

montelukast

Anti-IgE monoclonalAntibodiesomalizumab

Short acting ß2 agonists

Inhaled corticosteroidsCromoglycates

TheophyllineLeukotriene antagonists

Long acting ß2 agonists

Oral steroids

severity

reliever

preventer

controller