5.5 Antitussives
Cough suppressants are only beneficial where coughing is
persistent and unproductive, interferes with the animal’s
sleep and rest, or causes muscular fatigue and exhaustion.
They should not be used where there are excess secretions
in the tracheobronchial tree, as in chronic bronchitis or
bronchopneumonia. In general, the use of antitussives is
restricted to dogs.
Antitussive drugs are selected to exploit the cough suppressant
effects of opioid drugs, while minimising the sedative
and drug dependency characteristics.
Butorphanol is the most effective antitussive and is also a
potent opioid analgesic. Codeine phosphate is an opioid
antitussive, has little analgesic activity, and can induce constipation.
All opioid drugs should be used with caution in
cats. Dextromethorphan is used for relief of non-productive
cough; it has a central action on the cough centre in the
medulla. It is structually similar to opioids but has no analgesic
and limited sedative properties. Guaifenesin is
reported to increase the volume and reduce the viscosity of
tenacious sputum.
BUTORPHANOL
UK
Indications. Non-productive cough; analgesia (see section
6.3)
Contra-indications. Chronic bronchitis, bronchiectasis,
bronchopneumonia, or any other condition in which there is
excess airway secretion; conditions causing CNS depression;
hepatic impairment; cats
Side-effects. Mild sedation; rarely transient ataxia, anorexia
and diarrhoea; respiratory depression
Dose. Dogs: by mouth, 500 micrograms/kg 2–4 times daily
for up to 14 days
POM Torbutrol (Fort Dodge) UK
Tablets, butorphanol (as tartrate) 5 mg, 10 mg, for dogs
CODEINE PHOSPHATE
UK
Indications. Non-productive cough; analgesia (see section
6.3); non-specific diarrhoea (see section 3.1.2)
Contra-indications. See under Butorphanol
Side-effects. Sedation, ataxia; respiratory depression;
constipation
Dose. Dogs: by mouth, 0.5–2.0 mg/kg twice daily
POM Codeine Phosphate (Non-proprietary) UK
Tablets, codeine phosphate 15 mg, 30 mg, 60 mg
Syrup, codeine phosphate 5 mg/mL
POM Codeine Linctus (Non-proprietary) UK
Linctus, codeine phosphate 3 mg/mL
Note. Codeine linctus is categorised as P when a single dose is 5 mL or less
POM Codeine Linctus Paediatric (Non-proprietary) UK
Linctus, codeine phosphate 3 mg/5 mL
DEXTROMETHORPHAN HYDROBROMIDE
UK
Indications. Non-productive cough
Contra-indications. See under Butorphanol
Side-effects. See under Codeine phosphate
Dose. Dogs: by mouth, up to 5 mg 3–4 times daily
P Robitussin Dry Cough (Wyeth Consumer ) UK
Oral solution, dextromethorphan hydrobromide 1.5 mg/mL
P Robitussin Junior Persistant Cough (Wyeth Consumer) UK
Oral solution, dextromethorphan hydrobromide 750 micrograms/ mL
5.6 Respiratory stimulants
Respiratory stimulants are administered, at doses below the
convulsive threshold, to stimulate respiration. Their main
uses are to promote respiration in apnoeic newborn and preterm
animals and to reverse respiratory depression associated
with general anaesthetic, sedative, or hypnotic drugs.
These drugs should not be used as an alternative to patient
management because CNS stimulation my be followed by a
subsequent exacerbation of the depression. In drug-induced
respiratory depression maintenance of an adequate airway
and airflow by intubation and positive-pressure ventilation
are the recognised methods of treatment. While analeptic
drugs will temporarily increase tidal and minute volume,
the oxygen gain may be partly offset by increased brain
oxygen consumption.
All analeptics are CNS stimulants and may induce convulsions.
Doxapram is selective as a respiratory stimulant.
The principal mechanism of action of doxapram involves
stimulation of the peripheral aortic and carotid body chemoreceptors
rather than a central action.
The methylxanthines such as diprophylline and etamiphylline,
in addition to their bronchodilatory action,
increase respiratory drive by altering the sensitivity of the
respiratory centre to carbon dioxide. They are also non-specific
CNS stimulants.
DOXAPRAM HYDROCHLORIDE
UK
Indications. Respiratory stimulation of neonates; reversal
of respiratory depression associated with overdose of general
anaesthetic, hypnotic, and sedative drugs
Contra-indications. Convulsions, renal or hepatic disease,
hypocalcaemia
Side-effects. Convulsions
Warnings. Airway should be patent; overdosage may produce
hyperventilation, which may be followed by reduced
carbon dioxide tension in blood, cerebral vasoconstriction,
hypoxia, and possible brain damage; use with extreme caution
in dogs that have been sedated with morphine; see also
Drug Interactions – Appendix 1; excessive doses after
cyclopropane or halothane anaesthesia may precipitate cardiac
arrhythmias
Dose. Neonatal use.
Foals¨, calves: by subcutaneous, intramuscular or intravenous
injection, or by sublingual application, 40–100 mg
Lambs: by subcutaneous or intravenous injection, or by
sublingual application, 5–10 mg
Puppies: by subcutaneous or intravenous injection, or by
sublingual application, 1–5 mg
Kittens: by subcutaneous or intravenous injection, or by
sublingual application, 1–2 mg
Post-anaesthetic use.
Horses: by intravenous injection, 0.5–1.0 mg/kg
Dogs, cats: by intravenous injection, 1–2 mg/kg following
inhalational anaesthetic; 2–5 mg/kg following intravenous
anaesthetic
Dopram-V (Fort Dodge) UK
PML Oral drops, doxapram hydrochloride 20 mg/mL, for calves, lambs,
puppies, kittens
Withdrawal Periods. Should not be used in animals intended for human consumption
except neonates. Calves, lambs: slaughter 28 days
POM Injection, doxapram hydrochloride 20 mg/mL, for horses, dogs, cats
Withdrawal Periods. Should not be used in animals intended for human consumption
except neonates
ETAMIPHYLLINE CAMSILATE
(Etamiphylline camsylate)
UK
Indications. Respiratory stimulation of neonates; respiratory
disease where bronchodilation may be beneficial (see
section 5.1); myocardial stimulation (see section 4.1.3)
Dose. By mouth.
Calves: 700 mg repeated after 3–4 hours if required
Lambs: (2.5 kg bodyweight)
up to 280 mg. Dose may be repeated after 3–4
hours if required
PML Dalophylline (Arnolds) UK
Oral gel, etamiphylline camsilate 140 mg/unit dose, for calves, lambs;
metered-dose applicator (1 unit dose = 3.2 mL)
Withdrawal Periods. Calves, lambs: slaughter 7 days
Dose. Calves: 5 unit doses. May be repeated after 3–4 hours
Lambs: 1–2 unit doses. May be repeated after 3–4 hours
5.7 Nasal decongestants
Nasal decongestants contain alpha-adrenoceptor stimulants
to provide symptomatic relief in upper respiratory tract
problems associated with profuse secretion; they should be
used with caution. Pseudoephedrine may be of use in cats
with allergic rhinitis.
UK
Indications. Upper respiratory tract conditions with profuse
secretion
Dose. Cats: by mouth, 2–4 mg/kg twice daily
P Sudafed (Warner Lambert) UK
Elixir, pseudoephedrine hydrochloride 6 mg/mL
P Galpseud (Thornton & Ross) UK
Elixir, pseudoephedrine hydrochloride 6 mg/mL