Respiratory Stimulants

Doxapram hydrochloride (Dopram™).

Doxapram is an analeptic agent i.e. a central nervous stimulant. It is given intravenously and results in an increase in respiratory rate and tidal volume with a fall in pCO₂ and a rise in pO₂. This effect is thought to be mediated by stimulation of receptors in the carotid body leading to stimulation of the central respiratory drive.

The use of respiratory stimulants has largely been replaced by ventilatory support (especially as the widespread use of non-invasive forms of ventilation increases). However, it is used as an adjunct to non-invasive ventilation and in those who are unsuitable candidates for intubation and invasive ventilation.

Doxapram has a short half-life and is given intravenously as a continuous infusion - it requires an intact respiratory system to work. It can not be given through the same line as aminophylline as the two are incompatible.

• Role in treatment of ventilatory failure in COPD - although limited e.g. if ventilatory support contraindicated. ¹
• For short-term to rouse patients to aid in administering non-invasive ventilation or clearing secretions.
• Has been trialled in postoperative hypoxaemia.²

• Contraindicated in respiratory failure resulting from acute severe asthma, pulmonary embolism, pulmonary oedema and pneumothorax.
• Severe hypertension.
• Ischaemic heart disease.
• Epilepsy.
• Hyperthyroidism.
• Absolute contraindication in newborn and young children due to toxicity of preservative agent (benzyl alcohol - toxic in high doses).

• Ephedrine containing medications e.g. decongestants
• Sympathomimetics e.g. dopamine
• MAO I inhibitors

• Pain and redness at site of injection
• General stimulation of the nervous system occurs leading to tremor, muscle fasciculations and possibility of generalised seizures
• Sweating
• Anxiety and agitation - a common reason for patients to become distressed
• High blood pressure
• Tachycardia
• Headache
• Enlarged pupils
• Diarrhoea
• Nausea and vomiting
• Confusion
• Stimulation of the cardiac system - risk of arrhythmias

• Short-lived response.
• Provides short term improvement in arterial blood gases.⁵
• Given in hospital under specialist supervision (stimulates non-respiratory muscles also).
• Use of doxapram requires continuous respiratory and cardiovascular measurements (causes hypertension and tachycardia) and frequent arterial blood gas monitoring.
• Can induce panic attacks (used in research).