Posology Calculating the children dose

Lecture 4Part 1

Posology

• Posos =how much logy=science• Branch of medical sciences which deals with

How medicines are dosed to produce its therapeutic effect

• It also depends upon various factors like age, climate, weight, sex,severity of the disease and so on

Calculation of child dose

• Optimally calculated by using child’s body weight and the dose needed in mg\kg

• Without knowing these data the following formulas based on adult dose can be used– Fried’s rule for infants– Clark’s rule– Young’s rule for children >2years

Fried’s rule

Dose for infant= Age(month)*Adult dose

150

Clark’s rule

• Dose for child = weight(Ib)*adult dose150 Ib average adult wt

Young’s rule

• Dose of the child= Age(years) *Adult dose

Age +12

List of analgesics could be used in children

Drug dose

Acetaminophen <1 year :10-15 mg\kg repeated every 4-6 hr2yr: 20mg\kg

Ibuprofen 5 - 10 mg/kg every 8 hr

Example

• Dosage of Klacid Peadiatric Suspension:7.5 mg/kg twice daily.

taken with/without food• Assume a child 1 (wt =10kg)year old with lower respiratory tract infection what is the

proper dose for him?• Using Freid’s the dose = 12*500\150= 40 mg

• Using the dose mg\kg= 75mg twice diaily• Using Clark’s= 73.3 mg twice

Looking at klacid susp. formula for children

• Contains 125mg/5ml• Calculate : 125mg 5ml 75mg needed volume The needed dose= 3ml twice aday

Dosage of Klacid Peadiatric Suspension:

7.5 mg/kg twice daily.

Preservatives

Lecture 4Part 2

Preservatives

• Naturally occurring or synthetic substance that is added to products such as foods, pharmaceuticals, paints, biological samples, wood, etc. to prevent decomposition by microbial growth or by undesirable chemical changes

Preservatives may be

• Antimicrobial preservatives – which inhibit the growth of fungi, including molds

• Antioxidants – Such as oxygen absorbers, which inhibit the

oxidation of food constituents– Example: BHA

Common antimicrobial preservatives

• Parabens derivatives• Disodium EDTA• Benzalkanium chloride

Parabens

• Bactericidal and fungicidal properties• Parabens are esters of para-hydroxybenzoic

acid • Common parabens include :

– methylparaben (E number E218)– ethylparaben (E214)– propylparaben (E216) – butylparaben

Health issues

• Parabens are rapidly absorbed, metabolized, and excreted

• Can cause skin irritation and contact dermatitis• Average levels of 20 nanograms/gram of parabens

have been detected in a small sample of 20 breast tumors – Acts as xenoestrogen

• Methylparaben applied on the skin may react with UVB leading to increased skin aging and DNA damage

Regulation

• European Scientific Committee on Consumer Products (SCCP) stated in 2006 that the available data on parabens do not enable a decisive response to the question of whether propyl, butyl and isobutyl paraben can be safely used in cosmetic products at individual concentrations up to 0.4%

Benzalkanium chloride

• Skin antiseptic preperation • Advanced, next generation hand sanitizers • wet wipes • Eye and nasal drops, as a preservative • Cleaners for floor and hard surfaces as a

disinfectant • High-level surgical instrument sterilizing and

disinfection solutions • Air and surface spray disinfectants

Health issues • When used in inhalers it may causes paradoxical

bronchoconstriction• Eye preparations containing benzalkanium chloride

may increases the sensitivity of eye– Substituted with EDTA as a presevative – Some have packaged eye drops in single-use vials with no

preservative[for sensitive eyes• Refresh eye drops

• Disinfectant containing benzalkonium chloride and the related compound didecyldimethylammonium chloride (DDAC) has been identified as the most probable cause of birth defects and fertility problems in mice

EDTA

• Ethylenediaminetetraacetic acid• produced as several salts, notably disodium

EDTA and calcium disodium EDTA.

Uses

• In personal care products, it is added to cosmetics to improve their stability toward air.

• In soft drinks containing ascorbic acid and sodium benzoate EDTA mitigates formation of benzene (a carcinogen)

• serves as a preservative in ocular preparations and eyedrops

Uses • It is used to bind metal ions in the practice of chelation

therapy – for mercury , iron and lead poisoning

• This therapy is used to treat the complication of repeated blood transfusions, as would be applied to treat thalassaemia

• Alternative medical practitioners believe EDTA acts as a powerful antioxidant to prevent free radicals from injuring blood vessel walls, therefore reducing atherosclerosis

• However, the FDA has not approved the use of EDTA for the cleansing of heavy metals such as mercury from the body or for treatment of atherosclerosis

Health issues

• organic environmental pollutant• found to be both cytotoxic and weakly

genotoxic in laboratory animals

BHA

• Butylated hydroxyanisole (BHA) is an antioxidant

• E number E320 • BHA also is commonly used in medicines, such

as isotretinoin, lovastatin, and simvastatin• Acting as free radical scavengers, further free

radical reactions are prevented.

Health issues

• The US National Institutes of Health report that BHA is reasonably anticipated to be a human carcinogen based on evidence of carcinogenicity in experimental animals

• When administered in high doses as part of their diet, BHA causes papillomas and squamous cell carcinomas of the in rats and Syrian golden hamsters

Benzyl alchohol

• Benzyl alcohol is produced naturally by many plants and is commonly found in fruits and teas.

• It is also found in a variety of essential oils like jasmine

Uses

• often added to intravenous medication solutions as a preservative due to its bacteriostatic and antipruritic properties

• use of benzyl alcohol as a 5% solution has been approved by the U.S. FDA in the treatment of head lice in children older than 6 months and in adults – Not effective towards eggs

Health issues• It is oxidized rapidly in healthy individuals to benzoic acid, conjugated with

glycine in the liver, and excreted as hippuric acid• . High concentrations can result in toxic effects including:

– respiratory failure– Vasodilation– Hypotension– Convulsions– Paralysis

• Newborns, especially if critically ill, may not metabolize benzyl alcohol as readily as adults.

• Reports in the early 1980s of sixteen neonatal deaths associated with the use of saline flush solutions containing benzyl alcohol preservative led to recommendations to avoid its use in neonates

Polyaminopropyl biguanide PAPB

• Disinfectant and a preservative used for disinfection on skin and in cleaning solutions for contact lenses

• ingredient in many deodorant bodysprays• PAPB is specifically bactericidal at very low

concentrations (10 mg/l) and is also fungicidal

Health issues

• PAPB solutions are sold for use as a general disinfectant solution to be applied onto skin. As it is not cytotoxic, it can be applied directly into wounds

• It is also not irritating like more traditional disinfectants such as alcohols