prescriptive and non prescriptive (otc) drugs

Prescriptive and non-prescriptive (OTC) drugs

Dr. Binaya SapkotaBPharm, PharmD

Category of medicines

• 2 broad legal classifications of medications:1. Prescription-only medicines (POM)/Legend

medicines: Dispensed legally only on prescription

• Legend: That must appear on label of product by the manufacturer [i.e., “Caution: Dispensing Prohibited Without Prescription.”]

2. Non-prescription/Over-the-counter (OTC) medicines: Obtained without prescription

Medicines that are both OTC and POM

• Ibuprofen 200 mg [NSAID]: OTC for mild to moderate pain

• Ibuprofen (Higher dose): POM for rheumatoid arthritis (RA).

• Hence, “PMH” should include all POM, OTC & herbal medicines taken by pt., and any recent changes in dosing regimen (including generic & therapeutic substitutions).

Categorization of Medicines (Nepal)

• By Drug Act 1978 AD (2035 BS) Section 17.• Groups Ka, Kha & Ga• GROUP KA MEDICINES:

Amphetamine Azathioprine

Codeine Cyclophosphamide

Epinephrine Heparin

Fentanyl 6-Mercaptopurine

Methotrexate Methadone

Morphine Vincristine

Vinblastin Warfarin

Pethidine

Group Kha Medicines: Antibiotics, Hormones & General Therapeutic Agents (Nepal)

Acetazolamide Allopurinol

Amitriptyline Amphotericin B (AMB)

Beta-blockers (Propanolol, Isoproterenol)

Chloramphenicol

Clofazimine Cloxacillin

Dapsone Diazepam

Erythromycin Ethambutol

Frusemide Gentamicin

Glyceryl trinitrate Griseofulvin

Haloperidol Hormones (Insulin, Oxytocin, Dexamethasone, Betamethasone, Hydrocortisone, Prednisolone, Triamcinolone)

Group Kha Medicines: Antibiotics, Hormones & General Therapeutic Agents (Nepal)

Kanamycin LidocaineMetformin NeomycinNeostigmine NitrofurantoinPara-amino salicylic acid (PAS) Penicillins (Benzyl penicillin, Phenoxy-methyl

penicillin, Ampicillin, Amoxycillin)

Pentazocine PhytomenadionePilocarpine Polymyxin BPralidoxime PrimaquineProbenecid Promethazine hydrochlorideProtamine sulfate PyrazinamideProchlorperazine RifampicinSalbutamol StreptomycinTetracyclines SulfasalazineVerapamil inj.

Group Ga Medicines

Chlorpheniramine Cyanocobalamine

Diethylcarbamazine (DEC)

Diphenhydramine

Ibuprofen Mebendazole

Metronidazole Niclosamide

Paracetamol Promethazine theoclate

Pyrimethamine Thiamine hydrochloride

Prescription

• An order (paper or electronic document) for medication issued by a physician, dentist, or other licensed medical practitioner.

• Nurses, optometrists, pharmacists: Issue prescriptions under protocol in certain states of the USA

• Designates a specific medication and dosage to a particular pt. at a specified time.

Prescription

• Single prescription may contain single (or multiple) medication or surgical/suture items (e.g., wound dressings, blood glucose monitoring equipment, needles & syringes)

• A prescription is in effect 3 types of documents:

1. Clinical document2. Legal document3. Invoice

Prescription order

• Part of professional relationship among prescriber, pharmacist & pt. [Tri-partite members of “HC” delivery system]

• Prescribers: Generate prescriptions.• Pharmacists: Provide pharmaceutical care.• Pt.: Comply with prescription & instructions.

Pharmacists’ Responsibilities

• Fill prescription order & counsel pt. to improve pt.'s compliance.

• Advise prescriber of pt.’s medicine sensitivities, previous ADRs, interactions of prescribed medications

• Suggest alternative medicines for individual pt. as dictated by formularies.

Electronic prescription

• Imp. to minimize medication errors & enforce use of formulary.

• Physicians issue computerized prescription orders in developed countries.

• Orders then screened for potential errors & interactions, & sent directly to pharmacy for processing.

Eg., In the UK, National Health Service (NHS) generates electronic prescriptions.

Advantages of Electronic prescribing

• Reduces/eliminates medication errors a/w illegible handwriting.

• Prescribers can receive on-screen prompts for medicine-specific dosing information.

• Information from pt.’s medical record can be linked with prescription records.

• Prescribers notified if medicine is covered by pt.’s insurance plan.

• Refill requests expedited.

Components of Prescription [Both Paper & Electronic prescriptions

1. Name & address of prescriber2. Date of prescription3. Name, address & age of pt.4. Name of medicine (with strength & dosage

form): Dosage regimen5. Total amount to be dispensed or length of Rx

time6. Directions for use7. Prescriber’s signature: Legal requirement of

prescriptions

PRESCRIPTION:Name & address of prescriber

• Identifies who the prescriber is.

• Informs the pharmacist where to contact the prescriber if there is any issue related to prescription.

PRESCRIPTION: Date of prescription

• Identifies when prescription was written.• Law defines length of time until period of

validity.• In the UK, NHS prescriptions: Should be

dispensed within 6 months of date on prescription qException: Controlled medicines should

be dispensed within 28 days.

PRESCRIPTION: Name, address & age of pt.

• Identifies pt. who is to receive medicine.

• Age of pt.: Helpful for pharmacist to check the dose of medicine (if person is very young or very old.)

Name of medicine (with strength & dosage form): Dosage regimen

• Give specific directions.• Avoid vague directions such as “Take as

directed”: Little value to the pt.• State the amount to be used & no. of times a

day that it should be taken.• Pharmacist should ensure that pt. is clear

about how to use/take their medicine.

Generic name (Approved name/rINN)

• All medicines are given an approved name.• Adopted by the WHO• “Aka” rINN: Recommended International Non-

Preprietary Name• In the UK, prescribers use generic names for

cost-saving. [Reason: Generic products are less expensive than equivalent proprietary product.]

Generic name (Approved name/rINN)

• In the UK, if medicine is written in generic name in the prescription, any equivalent product can be supplied even if it has a proprietary name.

• Dispensing pharmacist who dispensed a more expensive proprietary product when the prescription was written generically, may lose money.

Proprietary name (Brand name/Trade name/Manufacturer’s name)

• Short, distinct & easy to remember & write.• Company that 1st manufacturers & markets a

medicine will give a proprietary name.• Company will apply for a trademark in respect

of the proprietary name.• Granting of a trademark means that no other

company can use that name.

Dosage Form

• Dosage Form: Type of formulated product [Eg.: Tablet, Capsule, Cream, Ointment, Ear/eye/nasal drops]

• Each dosage form: Available in no. of specialized forms. [Eg.: Tablets available as modified-release, enteric-coated, dispersible, chewable, etc.]

Dosage Form

• Dosage form should be stated on prescription if there is >1 form available. [Eg.: Glyreryl trinitrate available as tablet, modified-release tablet, inj., ointment, patch, etc.]

• Prescriber should state the precise form to ensure that the required product is supplied.

Strength

• Amount of drug in the dosage form or unit of a dosage form (e.g. a tablet, a capsule, a patch, etc.)

• Expressed in several ways • e.g. Strength of oral liquid: Expressed as

amount of drug per usual dose volume [Ampicillin suspension: 125 mg/5 mL & 500 mg/5 mL)

Dose

• Amount of drug taken at any one time.

• Expressed as weight of medicine (e.g. 500 mg) or volume of medicine solution (e.g. 5 mL, 2 drops) or no. of units (half a tablet, 2 capsules, 1 sachet, a patch).

Dosage regimen

• Frequency of administration or no. of times the dose is to be taken in a period of time. vE.g.: • 5 mL twice a day • Use the cream at night & in the morning.• 1 inj. every 4 weeks• 3 tablets three times a week

Total daily dose

• Calculated from dose & no. of times per day that the dose is taken.

• Sometimes, maximum doses of medicines in terms of per day (rather than separate dose): Also expressed. [e.g.: BNF states that total daily dose of Paracetamol PO is 4 g.]

PRESCRIPTION: Total amount to be dispensed or length of Rx time

• Total amount of medicine to be supplied to pt.• Expressed as no. of units (e.g. 21 tablets) or as

a volume (e.g. 100 mL of mixture, 5 mL of eye drops) or as a weight (e.g. 30 g of cream) or as a single pack size or multiple pack size (e.g. 1 tube of ointment).

PRESCRIPTION: Directions for use

• How to use (e.g. spread thinly, dissolve in water)

• Where to use (e.g. in eye, in ear, on scalp)• Why to use (e.g. for pain Mx, for sleeping)

Latin terms & abbreviations

• In the UK, prescriptions should be written in English & use of Latin term discouraged.

• However, use of some Latin terms persists.• Abbreviations may have different meaning in

different countries. [So, great care required to avoid errors created by mis-understanding.]

Latin abbreviations: Dosage forms

Abbreviation English nameCaps. CapsuleCrem. CreamGtt. DropsLiq. SolutionLot. LotionPast. PastePulv. PowderUng. Ointment

Latin Terms used in prescriptionsAbbreviation English namea.c. Before foodb.d./b.i.d. Twice dailyh.s. At bedtimeo.d. Every dayp.c. After foodp.r.n. When requiredq.i.d./q.d. Four times dailys.o.s. If necessarystat. Immediatelyt.d.s./t.i.d. Take three times daily

Public Health Implications of OTC Medicines

• Increase in Ibuprofen over-dosage in the UK after its introduction as OTC medication.

• Phenyl-propanolamine: Increased hemorrhagic shock. – So, withdrawn by USFDA. – Now, formulation changed to Phenylephrine

• Dextro-methorphan: Abused in high doses as a hallucinogen

Public Health Implications of OTC Medicines

• Paracetamol+Caffeine: Sleep disorders & rebound headache

• HTN: Related to POM & OTC medicines.• NSAIDs: Increase risk of hepatotoxicity & GI

hemorrhage in individuals who consume ≥3 alcoholic drinks daily.

Selection of OTC Medicines

• Select medicine with simplest regimen. – Single-ingredient products preferred.

• Same medicine “Acetaminophen” is in cough and cold preparations. – Pt. unaware of this may take separate doses of

analgesic; this may lead to hepatotoxicity.


• Select medicine containing effective dose.• Read product labeling carefully to determine

appropriate ingredients based on pt.’s symptoms & health conditions.

• Recommend a generic product.• Critically evaluate advertisements.


• Doses, dosage forms, palatibility of medicines: Imp. for children

• Lack of awareness of ingredients in OTC medicines & belief by “HPs” that OTC products are ineffective & harmless cause diagnostic confusion & interfere with therapy.

• Aspirin: Not used in children & adolescents for viral infections±fever. [Reason: Increased risk of Reye’s syndrome]


• Aspirin & other NSAIDs: Avoided by individuals with active PUD, & pt. taking oral anti-cogulants.

• Cimetidine: Inhibitor of hepatic drug metabolism, & increases blood levels & toxicity of Phenytoin, Theophylline, Warfarin.

Commonly used OTC Medicines of known efficacy

OTC Category

Medicine OTC medicines counseling

H2 receptor antagonists

Ranitidine Approved for relief of heartburn, acid indigestion.

Do not take for >2 weeks & for children <12 years of age.

Proton pump inhibitors (PPIs)

Omeprazole Do not take for >14 days or more often than every 4 months unless directed by physician.


OTC Category Medicine OTC medicines counseling

Allergy and “cold” preparations

Chlorpheniramine

Cetrizine

Diphenhydramine

Antihistamines alone relieve most symptoms a/w allergic rhinitis.

Chlorpheniramine causes less drowsiness than Diphenhydramine.

Cetrizine is a/w lower incidence of sedation.


OTC Category Medicine OTC medicines counseling

Analgesics and anti-pyretics

Acetaminophen

Aspirin

Ibuprofen

Naproxen sodium

Acetaminophen lacks anti-inflammatory activity. Do not exceed a total daily

Aspirin, Acetaminophen, Ibuprofen, Naproxen increase risk of hepatotoxicity and GI hemorrhage in individuals who consume ≥3 alcoholic drink daily.


OTC Category

Medicine OTC medicines counseling

Antacids Al(OH)3+Mg(OH)2

Combination OTC product less likely to cause constipation or diarrhea and offer high acid neutralizing capacity.Some preparations include Simethicone (anti-flatulant to relieve symptoms of bloating.)


OTC Category

Ingredient Comments and OTC medicines counseling

Anti-tussives Codeine Acts centrally to increase cough threshold.

Addiction liability low in doses required for cough suppression.

Hair growth stimulants

Minoxidil Rx for ≥4 months necessary to achieve visible results.

If new hair growth is observed, continued Rx necessary as hair density returns to pre-Rx levels within months following medicine discontinuation.

OTC Drug Interactions

OTC Medicines Interacting Medicine Nature of Interaction

NSAIDs: Ibuprofen, Aspirin

Methotrexate Reduced excretion of Methotrexate leading to increase in serum levels and toxicity.

Other NSAIDs, Corticosteroids

Increased risk of GI bleeding

Anticoagulants Anti-platelet action of Aspirin increases prothrombin times and increased likelihood of GI bleeding.

H2 Receptor antagonists (e.g., Cimetidine)

Anticoagulants, Phenytoin, Theophylline

Inhibits microsomal liver enzymes resulting in increased levels of medicines and toxicity.

OTC Drug Interactions

OTC Medicines Interacting Medicine Nature of Interaction

Sedative antihistamine (e.g., Chlorphenirmaine, Promethazine)

Alcohol Increased sedative effect

Antacids Ciprofloxacin, Phenytoin, Tetracyclines, Iron, Ketoconazole, Chloroquine

Chelation resulting in poor absorption if taken at same time of day.

OTC Medicines in Pregnancy and Lactation

• Consult with physician or pharmacist before taking OTC or POM.

• Be careful while taking medicines because most medicines pass into breast milk.

OTC Medicines in Children

• OTC medicines rarely come in one-size-fits-all.• Children are vulnerable to their untoward

effects because they are not just small adults.– So, do not estimate dose based on their size.

• Read the label. Follow all directions.• Do not double the dose just because the child

seems sicker than last time.

OTC Medicines in Children

• Consult with doctor or pharmacist before giving the child 2 medicines at same time.

• Never let children take medicines by themselves.

• Never call medicine candy to get kids to take it.

Bibliography

• Remington: The Science and Practice of Pharmacy 21st edition

• Pharmaceutical Practice 4th edition • Basic and Clinical Pharmacology 13th edition• Pharmacy Practice and The Law 4th edition

prescriptive and non prescriptive (otc) drugs

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