Allergic conditions

Question 1

role in the treatment + prevention of nausea + vomiting

Answer 1

Cyclizine, Cinnarizine and Promethazine

Question 2

Oral antihistamines are useful for

Answer 2

hayfever, rashes, itching, bites, stings + drug allergies.

Question 3

Hydroxyzine: MHRA

Answer 3

There is a risk of QT interval prolongation and torsade de pointes (abnormal heart rhythm that can lead to sudden cardiac death).

Question 4

Anaphylaxis

Answer 4

• The airway must be secure, and blood pressure must be restored by placing the patient in the recovery position if unconscious or nauseous or laying the patient flat + raising the legs
• Administration of Adrenaline (I.M. dose of 500mcg in >12y, 150mcg <5y), the dose may be repeated if necessary, after 5-minute intervals according to blood pressure, pulse and respiratory function.
• Administer high-flow oxygen and I.V. fluids.
• Administer an antihistamine such as chlorphenamine by slow I.V. or I.M. injection after Adrenaline.
• Administer an I.V. Corticosteroid (e.g. HC) to prevent further deterioration in severe patients.

 Continuing respiratory deterioration requires further treatment with bronchodilators including inhaled or I.V. Salbutamol, Ipratropium, aminophylline or magnesium sulphate in addition to oxygen

Question 5

for short-term and long-term prophylaxis of hereditary angioedema.

Answer 5

Tranexamic acid and danazol [unlicensed indication] are used

Question 6

Allergen-type Vaccines

Answer 6

 Desensitising vaccines should only be used for seasonal allergic hayfever (caused by pollen) that has not responded to anti-allergic drugs + hypersensitivity to wasp and bee venoms.
 Desensitising vaccines should generally be avoided in patients with asthma, pregnancy, <5y, with B-blockers/Ace inhibitors.

Question 7

Old antihistamine

Answer 7

SEDATING

• Promethazine (BD/TDS)
• Chlorphenamine (QDS)
• Hydroxyzine

Question 8

New antihistamines

Answer 8

NON- SEDATING

• Acrivastine (TDS)
• Cetirizine (OD)
• Loratidine (OD)
• Fexofenadine (OD)

Question 9

Important cautions of antihistamines

Answer 9

• Benign prostatic hyperplasia (urinary retention)
• Glaucoma (raised intraocular pressure)
• Severe liver impairment (sedation precipitates hepatic coma)

Question 10

Hydroxyzine CI

Answer 10

• Concomitant drugs that prolong QT interval
• CVD
• Family history of sudden death
• Hypokalaemia
• Hypomagnesaemia
• Bradycardia

Question 11

Adrenaline dose

Answer 11

<6: 150mcg
6-12: 300mcg
>12: 500mcg

Question 12

Angioedema anaphylaxis

Answer 12

• Adrenaline and oxygen
• antihistamine
• corticosteroid