PRN: Take the Medicine as Needed
PRN or pro re nata is a latin terminology, meaning ‘take the medicine as needed’. Doctors usually write this direction for some particular drugs. But what does PRN really mean?
- Medicine directions
- Drug groups applicable to the signa PRN
- ‘As needed’, what does this really mean?
- A case of an unnecessary drug intake
Most patients are accustomed with the directions OD meaning once a day, TID meaning three times a day or BID meaning twice a day but PRN? Some tend to ask, how many times do I take it again?
Fortunately there are only a few drug groups in which this direction can be applicable.
Drug groups applicable to the signa PRN
The pain relievers
These include the analgesics – opioid and non-opioid like morphine and tramadol (Tramal), paracetamol (Biogesic), ibuprofen (Advil), mefenamic (Ponstan), diclofenac (Voltaren), celecoxib (Celebrex), naproxen (Naprosyn), piroxicam (Feldene) etc.
The nasal decongestants
Nasal decongestant relieves runny nose. This can be in single or in combination form. The active constituent is phenylpropanolamine or phenylephrine.
The anti- pyretic
The anti-pyretics includes aspirin (Cortal), ibuprofen (Dolan) and paracetamol (Tylenol). This group is for fever.
Antihistamines are also referred to as anti-allergy medications. This can also be in single or in combination form with other active constituents. Examples of antihistamines are loratadine (Claritin), cetirizine (Virlix), diphenhydramine (Benadryl), chlorpheniramine (Antamin) etc.
These types relive hyperacidity of the stomach. The combination Aluminum and Magnesium hydroxide (Maalox) is a popular over-the –counter antacid.
The anti-emetics refer to drugs that prevent vomiting. Examples of these are the dimenhyrinate, meclizine (Bonamine), metoclopramide (Plasil) etc.
‘As needed’, what does this really mean?
Antibiotics are required to have a full dosage regimen from three to seven days to stop or kill the infection. Maintenance medications as amlodipine, losartan, nifedipine etc. and the anti- diabetics are strictly to be taken daily to control blood pressure and sugar respectively. In addition, in order to calm down an acid reflux condition, a Prilosec or Nexium should be taken for fourteen days.
The citations mentioned have definite dosage instructions to ensure positive results.
The signa PRN or as needed, simply instructs the patient to take the medicine ONLY when he needs it. A NSAID for example like the mefenamic - an analgesic is usually taken 3 times a day. However, when a physician jots down PRN, he instructs the patient to take the drug once a symptom of pain is experienced. The maximum dosing of mefenamic maybe three times a day but once the relief is achieved with the single take, the consumption of the following dose is not necessary anymore.
‘As needed’ means, don’t take an antipyretic if you do not have a fever or do not take Plasil if you are not experiencing a vomiting tendency.
A case of an unnecessary drug intake
A girl about 14 was brought back by a mother to a family doctor after a week. She was shaking violently as if having a seizure. This girl was diagnosed to have a swollen tonsillitis with fever and flu seven days ago. She was given an antibiotic for the infection, a paracetamol for her fever and some cold medicine. She was also vomiting that the doctor gave her metoclopramide to be taken ‘as necessary.’
The metoclopramide has a strength of 10 mg. For some reason, the mother mistook the strength of the drug for the number of tablets. The doctor only prescribed 6 tablets but the mother bought 10 tablets. She gave the metoclopramide drug for her daughter 3 times a day for 3 days. It was on the third day that this girl suddenly experienced the shaking episodes. As it turned out, the girl suffered from Extrapyramidal reactions – a side effect of Metoclopramide characterized by abnormal involuntary movements of the body.
(c) Phoenix Montoya @ October 7, 2010
More articles by this author:
Is a Generic Drug Effective as a Branded Type?
Ibuprofen Capsule Facts and Safety
Maalox, Tums, Geltazine and Other Antacid Dangers
Claritin: Less Sedating Anti-allergy Drug
Advil image source by ValerieMorrisonPhotography.com
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