Symptoms in the Pharmacy :Respiratory Problems (2)

cold and flu

When to refer

• Earache not settling with analgesic 
• Facial pain/frontal headache
• In the very young
• In the very old
• In those with heart or lung disease, e.g. chronic bronchitis
• With persisting fever and productive cough
• With delirium
• With pleuritic chest pain 
• Asthma

Treatment timescale

Once the pharmacist has recommended treatment, patients should be

advised to see their doctor in 10–14 days if the cold has not improved.

Management

The use of OTC medicines in the treatment of colds and flu is widespread

and such products are heavily advertised to the public. There is

little doubt that appropriate symptomatic treatment can make the

patient feel better; the placebo effect also plays an important part

here. For some medicines used in the treatment of colds, particularly

older medicines, there is little evidence available from which to judge

effectiveness. The pharmacist’s role is to select appropriate treatment

based on the patient’s symptoms and available evidence, and taking

into account the patient’s preferences. Polypharmacy abounds in

the area of cold treatments and patients should not be overtreated.

The discussion of medicines that follows is based on individual

constituents; the pharmacist can decide whether a combination of

two or more drugs is needed.

Decongestants

Sympathomimetics

Sympathomimetics (e.g. pseudoephedrine) can be effective in reducing

nasal congestion. Nasal decongestants work by constricting the

dilated blood vessels in the nasal mucosa. The nasal membranes are

effectively shrunk, so that drainage of mucus and circulation of air

are improved and the feeling of nasal stuffiness is relieved. These

medicines can be given orally or applied topically. Tablets and syrups

are available, as are nasal sprays and drops. If nasal sprays/drops are

to be recommended, the pharmacist should advise the patient not to

use the product for longer than 7 days. Rebound congestion (rhinitis

medicamentosa) can occur with topically applied but not oral sympathomimetics.

The decongestant effects of topical products containing

oxymetazoline or xylometazoline are longer lasting (up to 6 h)

than those of some other preparations such as ephedrine. The pharmacist

can give useful advice about the correct way to administer nasal

drops and sprays.

Problems

The pharmacist should be aware that some of these drugs

(e.g. ephedrine, pseudoephedrine), when taken orally, have the potential

to keep patients awake because of their stimulating effects on the

central nervous system (CNS). In general, ephedrine is more likely to

produce this effect than the other sympathomimetics. It is reasonable

to suggest that the patient avoids taking a dose of the medicine near

bedtime.

Sympathomimetics can cause stimulation of the heart, an increase

in blood pressure, and may affect diabetic control because they

can increase blood glucose levels. They should be used with caution

(current BNF warnings) in people with diabetes, those with

heart disease or hypertension, and those with hyperthyroidism. Hyperthyroid

patients’ hearts are more vulnerable to irregularity, so

that stimulation of the heart is particularly undesirable for such

patients.

Sympathomimetics are most likely to cause these unwanted effects

when taken by mouth and are unlikely to do so when used topically.

Nasal drops and sprays containing sympathomimetics can therefore

be recommended for those patients in whom the oral drugs are less

suitable. Saline nasal drops or the use of inhalations would be other

possible choices for patients in this group.

The interaction between sympathomimetics and monoamine

oxidase inhibitors (MAOIs) is potentially extremely serious; a hypertensive

crisis can be induced and several deaths have occurred in such

cases. This interaction can occur up to 2 weeks after a patient has

stopped taking the MAOI, so the pharmacist must establish any

recently discontinued medication. There is a possibility that topically

applied sympathomimetics could induce such a reaction in a patient

taking an MAOI. It is therefore advisable to avoid both oral and

topical sympathomimetics in patients taking MAOIs.

Cautions:

• diabetes
• heart disease
• hypertension
• hyperthyroidism

Interactions. 

Avoid in those taking

• MAOIs (e.g. phenelzine)
• reversible inhibitors of monoamine oxidase A (RIMAs) (e.g.moclobemide)
• beta-blockers
• tricyclic antidepressants (e.g. amitriptyline) – a theoretical interaction that appears not to be a problem in practice.

Phenylpropanolamine and stroke

A study conducted in the USA showed an association between the

use of phenylpropanolamine (PPA) and haemorrhagic stroke. The

most significant increased risk in the US study was among women

who took PPA in appetite-suppressant products, which are not available

in the UK. It is important to note that there are differences

between the USA and the UK in the way PPA is used as a

non-prescription medicine. The maximum daily dose is 100 mg in

the UK compared with 150 mg in the USA. A review conducted by

the UK Committee on Safety of Medicines in 2000 concluded that

any risk associated with PPA use in preparations and doses used in the

UK appears to be very small. Nevertheless, most UK products

containing an oral decongestant have since been reformulated to

exclude PPA.

Antihistamines 

Antihistamines can reduce some of the symptoms of a cold: runny nose

(rhinorrhoea) and sneezing. These effects are due to the anticholinergic

action of antihistamines. The older drugs (e.g. chlorphenamine

(chlorpheniramine), promethazine) have more pronounced anticholinergic

actions than do the non-sedating antihistamines (e.g. loratadine,

cetirizine, acrivastine). Antihistamines are not so effective

at reducing nasal congestion. Some (e.g. diphenhydramine) may also

be included in cold remedies for their supposed antitussive action

 or to help the patient to sleep (included in combination

products intended to be taken at night)

Interactions

The problem of using antihistamines, particularly

the older types (e.g. chlorphenamine), is that they can cause

drowsiness. Alcohol will increase this effect, as will drugs such as

benzodiazepines, phenothiazines or barbiturates that have the ability

to cause drowsiness or CNS depression. Antihistamines with known

sedative effects should never be recommended for anyone who

is driving, or in whom an impaired level of consciousness may be

dangerous (e.g. operators of machinery at work).

Because of their anticholinergic activity, the older antihistamines

may produce the same adverse effects as anticholinergic drugs (i.e. dry

mouth, blurred vision, constipation and urinary retention). These

effects are more likely if antihistamines are given concurrently

with anticholinergics such as hyoscine, or with drugs that have

anticholinergic actions such as tricyclic antidepressants.

Antihistamines should be avoided in patients with prostatic hypertrophy

and closed-angle glaucoma because of possible anticholinergic

side-effects. In patients with closed-angle glaucoma they may cause

increased intraocular pressure. Anticholinergic drugs can occasionally

precipitate acute urinary retention in predisposed patients, e.g. men

with prostatic hypertrophy.

While the probability of such serious adverse effects is low, the

pharmacist should be aware of the origin of possible adverse effects

from OTC medicines.

At high doses, antihistamines can produce stimulation rather than

depression of the CNS. There have been occasional reports of fits

being induced at very high doses of antihistamines and it is for this

reason that it has been argued that they should be avoided in epileptic

patients. However, this appears to be a theoretical rather than a

practical problem. Antihistamines can theoretically antagonise the

effects of betahistine.

Interactions:

• alcohol
• hypnotics
• sedatives
• betahistine
• anticholinergics, e.g. trihexyphenidyl (benzhexol), tricyclics

Side-effects:

• drowsiness (driving, occupational hazard)
• constipation
• blurred vision

Cautions:

• closed-angle glaucoma
• prostatic obstruction
• epilepsy
• liver disease

Zinc

Two systematic reviews have found limited evidence that zinc gluconate

or acetate lozenges may reduce continuing symptoms at 7 days

compared with placebo. Thus there is indication of some benefit.

Echinacea

A systematic review of trials indicated that some echinacea preparations

may be better than placebo or no treatment for the prevention

and treatment of colds. However, due to variations in preparations

containing echinacea, there is insufficient evidence to recommend

a specific product.

Vitamin C

A systematic review found that high-dose vitamin C (over 1 g per day)

reduced the duration of colds by about half a day (a reduction of

approximately 15% in duration).