Summer 2019 MSBTE solved answers

SUMMER 2019 MSBTE Board paper answers

Q.1 a. Why gargles are submitted in concentrated form?

Gargles are submitted in concentrated form because,

 The quantity of solution require for doing one time gargle is around 20 ml.

 Therefore if it is dispensed in dilute form it requires the large quantity which is practically impossible to dispense.

 Therefore they are dispensed in concentrated form

b. What is double wrapping? Where it is useful?

When wrapping is done in white glazed paper which is lined with waxed paper is called as double wrapping. The lining is cut a few mm smaller than the white glazed paper and is quite satisfactory to fold both papers together.

It is useful for wrapping of volatile, hygroscopic and deliquescent substances

c. Discuss the drawbacks of cocoa butter as a suppository base.

Following are drawbacks of cocoa butter as a suppository base-

 Exhibits marked polymorphism.

 Rancidity.

 Stick to mould.

 Leakage from body cavity.

 Costly.

 Immiscibility with body fluid.

 Chloral hydrate or lactic acid liquefies it.

 Melts in warm weather

d. Give the metric equivalent of the following:

i) 1 pound – 450 gram

ii) 1 grain – 64.8 mg/60mg

iii) 1 dessert spoonful – 8.00 ml

iv) 15 minim – 0.06 x 15 = 0.9 ml

e. List reasons causing therapeutic incompatibility.

Following are reasons causing therapeutic incompatibility

 Error in dosage.

 Wrong dose or dosage form.

 Synergism and Antagonism drug.

 Contraindication.

 Drug interactions

f. Define with example (any one)

i) Douches – Douches are medicated soln. for rinsing body cavity mostly for bladder, vagina, rectum, nasal cavity.

E.g. Potassium permanganate douche solution, Isotonic sodium chloride solution etc.

ii) Gargles – Gargles are clear aqueous solutions used to prevent or treat throat infections. They are brought into intimate contact with the mucous membrane of the throat and are allowed to remain in contact with it for few seconds, before they are thrown out of the mouth.

E.g. Potassium chlorate and Phenol gargles B.P.C,

Phenol gargles ,

Potassium chloride and phenol gargle

iii) Inhalations – Inhalations are solutions or suspensions of volatile, aromatic

substances administered by the nasal or oral respiratory route in the form of

vapour inhaled from the surface of hot water.

Eg. Eucalyptus oil Inhalations

g. What is HLB? Give it’s significance.

Griffin devised useful method for calculating balanced mixtures of emulsifying agents to provide a particular type of emulsion.in which every emulsifying agent has given number ranging from 1-18 .It is called as HLB or (Hydrophilic – Lipophilic Balance System .

Significance –

It is very difficult to select a proper emulsifying agents for the preparation of a stable emulsion from large number of emulsifying agents. No single emulsifying agent possess all the properties required for preparation of stable emulsion. So sometimes it is necessary to use two or more than two emulsifying agents instead of one to prepare stable emulsion

h. Give any four qualities of a good suspension.

The qualities of Ideal suspension-

 It should settle slowly

 It should be readily re-dispersed on gentle shaking of the container.

 It should pour readily and evenly from its container.

 It should be chemically inert.

 The suspended particle should not form a cake.

 It should be free from large particles which spoils its appearance & give gritty taste to oral preparation and also cause irritation to sensitive tissues when applied externally

i.Define antiperspirants and deodorants.

Antiperspirants: These are the agents used to prevent the flow of perspiration to overcome bad smell which is due to bacterial decomposition

Eg. Aluminium salts

Deodorants: Deodorant inhibits the formation of bad odour in perspiration by suppressing the growth of bacteria or masks the unpleasant odour

Eg Salicyclic acid, boric acid, zinc stearate

j. Give the reasons, “glycerine is choice of vehicle for throat paints.”

Glycerine is used as vehicle in throat paint because-

 Glycerine is viscous in nature and adheres to the throat

 Increases contact time and prolong the action

 It is also act as soothing agent

k. White Vaseline is not used in ophthalmic ointment. Why?

White Vaseline is obtained from yellow soft paraffin by bleaching. White Vaseline is not used in ophthalmic ointment because it may contain small traces of bleaching agent which are left over after bleaching the yellow soft paraffin. Hence white Vaseline may cause irritation to eye

l. What are the advantages of parenteral products?

Advantages of parental products -

 Rapid onset of action.

 Immediate therapeutic action is possible.

 Each dose can be administered accurately.

 When oral route is not possible in unconscious and non-co-operative patient.

 When drugs get inactivated in GIT tract

 Prolong action can be possible by this route.

 Absorption of the drug faster compare to other route

2. a. Write the advantages and disadvantages of powder as a dosage form.

ADVANTAGES

 Faster dispersal of medicament compared to tablet, capsules

 Convenient for dispersing bulky drug.

 Dry therefore stable, less incompatible , rapid onset of action.

 Convenient for children & elderly patients.

 Economical.

DISADVANTAGES

• Drugs having bitter, nauseous, unpleasant taste cannot be dispensed in powder form.

• Deliquescent & Hygroscopic drug cannot be given in powder form.

• Drugs affected by atmospheric condition cannot be given in powder form.

• Dispensing is time consuming

• Weighing difficulty ( qty. Less than 100mg.)

2.b. Define incompatibility. What is tolerated and adjusted incompatibility?

Incompatibility:- Incompatibility occurs as a result of mixing two or more antagonistic substances & an undesirable product is formed which may affect the safety, efficacy & appearance of the pharmaceutical preparation.

1. Tolerated incompatibility -

In this type of incompatibility, chemical reaction can be reduced by mixing the solutions in dilute forms or by changing the order of mixing but no alteration is made.

Example (any one example)

Rx

Sodium bicarbonate ………… 1g

Borax ……………………….. 1 g

Phenol ………………………. 0.5g

Glycerine …………………….. 20 ml

Water …………….upto…….. 90 ml

Make a spray solution,

When sodium bicarbonate, borax and glycerine are mixed together in the presence of water, a reaction takes place with the evolution of carbon dioxide. If the mixture is dispensed as such, there are chances of bursting the bottle. Therefore, mix these ingredients in an open vessel until the evolution of carbon dioxide ceases add phenol and transfer the mixture to a bottle.

2. Adjusted incompatibility -

In this type of incompatibility, change in the formulation is needed with a compound of equal therapeutic value

e.g. in the mixture of caffeine citrate and sodium salicylate, caffeine citrate is replaced with caffeine.

Example (any one example)

Rx Caffeine citrate …………… 1g

Sodium salicylate …………. 3g

Water …………………. 90ml

Caffeine citrate is a mixture of equal weights of caffeine and citric acid. the citric acid present in caffeine citrate reacts with sodium salicylate to liberate salicylic acid which get precipitated. If caffeine is used instead of caffeine citrate it forms a soluble complex with sodium salicylates. Hence substitute caffeine citrate with half as much caffeine as that of caffeine citrate to form a clear mixture.

2.c. Explain the term superscription, inscription and subscription.

Superscription: It consist of symbol Rx which is instruction to pharmacist. Rx stands for Latin word recipe meaning ‘ you take’ and Rx represents sign of Jupiter meaning God of healing. This is for praying quick recovery of patient.

Inscription: This is main part of prescription order , contains name and quantities of the prescribed ingredients.

Subscription: It contain direction to the pharmacist for preparing prescription which is usually ‘Mix’,‘ Send tablets’, or ‘capsules’ etc.

2.d.What are elixirs? How do they differ from syrup?

Elixirs - Elixirs are clear, sweetened and flavoured hydro alcoholic liquid preparation intended for oral use.
Elixirs are clear, sweetened and flavoured hydro alcoholic liquid preparation intended for oral use.	Syrup is sweet, viscous, concentrated or nearly saturated aqueous solution of sucrose containing 66.7% w/w of sugar
Uses: Can be used as Antibiotic Antihistaminic Sedative purpose	Uses: Can be simple syrup use for sweetening and flavouring purpose and medicated syrup for therapeutic purpose
More viscous than elixir and less viscous than linctus	less viscous than syrup
Ex Tolu syrup, ginger syrup ect.	Ex chloral hydrate elixir ect

2.e. Describe layout of sterile product area

Clean up area:-In such area cleaning and steaming of packing materials and utensils is done therefore the walls and ceiling are constructed in such a way, that they withstand the effects of steam and chemicals. Generally, epoxy or vinyl paint is coated to solve the purpose. This area must be kept clean by washing it regularly. Precaution must be taken to prevent the growth of microorganism and collection of dust.

Compounding area:-It is nothing but a “preparation” area, where the formula is compounded, and not necessarily aseptic. There should be strict control it that these should not catch dust. The cabinets and counters should be of stainless steel. Ceiling wall and floor should be sealed and can be coated with Epoxy paint. Adequate sink and counter space should be provided.

Aseptic Area: - It is an entirely sealed area from outside atmosphere to keep aseptic environment free from physical and biological contamination. Therefore, at the time of designing and constructing the aseptic area civil work can compose to HVAC (High ventilating and air conditioning) system including the electrical wire and switches. The walls facing outside should have double walled glass partition. Epoxy paints should be used to prevent wall, ceiling ,and floor from the accumulation of dust and microorganisms

The air in the aseptic area should be free from fibers ,,dust and microorganism. This can be achieved by the use of high efficiency particulate air filers (HEPA) which can remove particles upto 0.3 um. HEPA filters are fitted in laminar air flow system in which air free from dust and microorganism flows with uniform velocity. The air is supplied under positive pressure which prevents particulate contamination from sweeping from adjoining areas .Ultraviolet lamps are fitted to maintain sterility.

. The personnel enter in this area through air lock door. Movement should be minimum and restricted during filling procedure

. Quarantine area:- Approved batches from QC department can be kept here before labelling and packing.It must contain space that separates ‘Approved batches’ and ‘In process batches’.This area is only restricted to a responsible person. Labelling and packing area:-Adequate space is required for installation of printing devices and packaging machines In this area, label printing and labelling can be take place. Storage and its disposal:- The finished product are stored under specified storage condition and dispensed off. 2f.Translate the following terms in English: i) Capiendus – To be taken ii) Guttae – A drop, iii) Hora somni – Every hour iv) Trochiscus – A lozenge v) Unguentum – An ointment vi) Dolere urgente – When the pain is severe

Pharmaceutical Powders

SOLID DOSAGE FORMS: POWDERS

A pharmaceutical powder  It is a preparation in which drug is blended with other powdered substances and used for internal or external purpose, is solid dosage form which contains mixture of finely divided drugs or chemicals in a dry form meant for internal or external use.

Advantages:

• Powder form is the most versatile and convenient to prescribe, compound and administer.
• can be administered easily to infants and young children who cannot swallow tablets or capsules
• Powders are stable and do not enter into reaction in solid state, lesser difficulties are experienced in compounding them together
• Less incompatibility and more stable as compared to liquid dosage form
• Powders will have a rapid onset of action since disintegration is not required
• These can be applied to many body cavities such as ears, nose, tooth socket, throat
• drugs tend to most stable as a solid
• Powders can be made into many different dosage formulations (capsules, tablets, powders for reconstitution, dusting powders, bulk powders, powders for inhalation, etc.

Disadvantages:

• As compared to other dosage forms, powders are time consuming to compound
• Volatile, hygroscopic, oxidizing and deliquescent drugs create obvious difficulties when dispensed as powders·
• Patient may misunderstand the correct method of use. Without clear instruction, patients may inhale through the nose a drug intended for oral administration. In oral administration, it may have to be clear whether the drug has to be dissolved first in water or taken as it is.
• Dose inaccuracy, not advisable for potent drugs.
•  Not suitable for drugs which are not stable under normal atmospheric conditions.
• Not suitable for drugs which are inactivated or cause gastric irritation, such drugs should be formulated as enteric coated tablets.

Pharmaceutical powders are formulated to be exist as fine particles. The powders are then smooth to the touch and nonirritating to the skin. Powdes generally range from 0.1 to 10 micron in size.

A uniform particle size distribution insures an uniform dissolution rate if the powder is to dissolve, an uniform sedimentation rate if the powder is used in a suspension, and minimizes stratification when powders are stored or transported.

Reducing the particle size of a powder will result in an uniform distribution of particle sizes. The process of reducing the particle size is called comminution. In extemporaneous compounding, there are three methods of comminution or size reduction methods.

• Trituration is the continuous rubbing or grinding of the powder in a mortar with a pestle. This method is used when working with hard, fracturable powders.
• Pulverization by Intervention is used with hard crystalline powders that do not crush or triturate easily, or gummy-type substances. The first step is to use an "intervening" solvent (such as alcohol or acetone) that will dissolve the compound. The dissolved powder is then mixed in a mortar or spread on an ointment slab to enhance the evaporation of the solvent. As the solvent evaporates, the powder will recrystallize out of solution as fine particles.
• Levigation reduces the particle size by triturating it in a mortar or spatulating it on an ointment slab or pad with a small amount of a liquid in which the solid is not soluble. The solvent should be somewhat viscous such as mineral oil or glycerin. This method is also used to reduce the particle size of insoluble materials when compounding ointments and suspensions.                                                                                                                                                                                                                                                                                                                                                              Simple & Compound Powders: The number of ingredient is one i.e. each individual dose is enclosed in paper, called as simple powder while more than one ingredients are present it is defined as compound powder.Minimum weighable quantity on dispensing balance is 100 mg.                                                                                                                                                  Classification of powders:
  1. Bulk powders for external use: Zinc undecenoate powder
  (a) Dusting powders (b) Snuffs (c) Dental powders (d) Insufflations
  2. Bulk powders for internal use: Compound Rhubarb Powder.
  3. Simple and compound powders for internal use:Magnesium trisilicate compound powder
  4. Effervescent granules: antacid powders
  5. Cachets: Isoniazid cachetsr
  1. Bulk powders for external use
  External bulk powders contain non-potent substances for external applications. These powders are dispensed in glass, plastic wide mouth bottles and also in cardboard with specific method of application. Bulk powders for external used are of four types. (a) Dusting powders (b) Snuffs (c) Douche powders (d) Dental powder (e) Insufflation
  (a) Dusting powders
  These are used externally for local application not intended for systemic action. The desired characteristics of powders include- (a) homogeneity, (b) non-irritability, (c) free flow, (d) good spreadability and covering capability, (e) adsorption and absorption capacity, (f) very fine state of subdivision, and (g) capacity to protect the skin against irritation caused by friction, moisture or chemical irritants.
  Dusting powders usually contain substances such as zinc oxide, starch and boric acid or natural mineral substances such as kaolin or talc.
  Talc may be contaminated with pathogenic microorganisms such as – Clostridium tetani etc., and hence it should be sterilized by dry heat. Dusting powders should not be applied to broken skin. If desired, powders should be micronised or passed through a sieve # 80 or 100. Dusting powders should preferably be dispensed in sifter-top containers. Such containers provide the protection from air, moisture and contamination as well as convenience of application. Currently some foot powders and talcum powders have been marketed as pressure aerosols.
  Dusting powders are employed chiefly as lubricants, protectives, absorbents, antiseptics, antipruritics, astringents and antiperspirants.
  Rx       Zinc oxide 20 parts
  Salicylic acid 2 parts
  Starch powder 78 parts
  (b) Snuffs
  These are finely divided solid dosage forms of medicaments dispensed in flat metal boxes with hinged lid. These powders are inhaled into nostrils for decongestion, antiseptic, and bronchodilator action.
  (c) Douche powder
  These powders are intended to be used as antiseptics or cleansing agents for a body cavity; most commonly for vaginal use although they may be formulated for nasal, otic or ophthalmic use also. As douche powder formulation often include aromatic oils, it becomes necessary to pass them through a # 40 or 60 sieve to eliminate agglomeration and to ensure complete mixing. They can be dispensed either in wide mouth glass bottles or in powder boxes but the former are preferred because of protection afforded against air and moisture.
  Rx
  Zinc sulphate
  Magnesium sulphate
  Boric acid
  Oil of lemon
  Water
  (d) Dental powders
  Dental powders are rarely prescribed. However this class of powders is interesting from the compounding angle. This preparation is a type of dentifrice meant for cleaning the teeth.
  As such, dental powders contain detergents, abrasives, antiseptics and colouring and flavouring agents incorporated in a suitable base. Generally the base is calcium carbonate. The detergent is in the form of soap and the abrasive action is provided by finely powdered pumice stone.
  Essential oils are added to provide flavour and freshness to the mouth as well as antiseptic action. Essential oils, if present in smaller quantity, are easily absorbed by calcium carbonate and pumice. This makes the uniform distribution of the oil difficult. Best results are obtained if the oil is triturated in the solids taking considerable care to distribute it uniformly.
  (e) Insufflation
  Insufflations are a class of powders meant for application to the body cavities e.g., ear, nose, vagina etc. The powder has to be extremely fine and must find an entry to the cavity deep enough to bring about its action at the site. It is delivered to the affected part in a stream with the help of a device called an insufflator, which blows the powder to the site.
  Some of the insufflations contain volatile liquid ingredients which may require uniform distribution in the powder. If these liquid ingredients are present in large quantity, the liquid portion may have to be evaporated. Generally evaporation is brought about slowly in a china dish which is heated on a water bath. The resultant product is re-powdered and sifted through a sieve of a suitable size.
  However, active volatile liquids present in small portions should not be removed by evaporation but only incorporated by trituration in the powder.
  The pharmaceutical industry packages the insufflations in pressurized form i.e., aerosols. Aerosols contain the medication in a stout container with a suitable valve, the delivery of the powder being accomplished by a liquefied or compressed gas propellant of very low boiling point. On pressing the actuator of the valve the propellant delivers the medication in a stream

  2. Bulk powders for internal use

  Bulk powders contain many doses in a wide-mouth container that is suitable to remove the powder by a teaspoon. The non-potent substances are used in bulk powder form such as antacid, laxative, purgative, etc.
  Rx
  Rhubarb powder
  Light magnesium carbonate
  Heavy magnesium carbonate
  Ginger powder
  Make a powder.

  3. Simple and compound powders for internal use.

  These are unit dose powders normally packed in properly folded papers and dispensed in envelopes, metal foil, small heat-sealed plastic bags or other containers.
  Usually for the preparation of simple powders, the ingredients are weighed correctly and blended by geometrical mixing in ascending order of weights. The mixture is then either divided into blocks of equal size, numbers of blocks representing the number of powders to be dispensed or each dose is weighed separately and placed on a powder paper. The paper is then folded according to the pharmaceutical art and placed in either an envelope or a powder box

  4. Effervescent granules

  This class of preparations can be supplied either by compounding the ingredients as granules or dispensed in the form of salts. The ingredients whether in granular form or present as salts, react in presence of water evolving carbon dioxide gas.
  For evolution of the gas two constituents are essential, a soluble carbonate such as sodium bicarbonate and an organic acid such as citric or tartaric acid. The preparation can be supplied either as a bulk powder or distributed in individual powders.
  There are three alternative methods of dispensing depending upon the nature of prescription.
  (i) If the effervescent salts are prescribed to be the dispensed in bulk form, no granulation is necessary. The ingredients are mixed uniformly and directions stated on the label to add the prescribed quantity to water, before use.
  (ii) If the effervescent salt is prescribed in divided doses, the ingredients which cause effervescence on mixing with water are enclosed separately in papers of different colour. The patient is advised to take one powder of each colour and add to water, before use. Quantities of the sodium bicarbonate and the organic acid, citric or tartaric, are equimolecular in proportion.
  (iii) In the third case the product contains all the ingredients mixed together in a granular form. Preparation of granular products requires pharmaceutical technique. If sodium bicarbonate and citric acid are taken in equimolecular proportion and mixed to make granules, the quantity of water of crystallization liberated from the citric acid is large enough to make the mass wet and carbon dioxide may be liberated during the preparation itself. If one tries to substitute citric acid by tartaric acid, which contains no water of crystallization; it may not be possible to form a mass necessary for granulation.
  Therefore both citric and tartaric acids are taken in suitable proportions leaving a little acid in surplus than the quantity required to neutralize sodium bicarbonate. This surplus is necessary to give the final preparation an acidic taste that is more palatable. There is a certain loss in weight of such a preparation due to the loss of water in drying the granules and partial loss of carbon dioxide due to its release during preparation.
  Heating is done on a water bath keeping all the ingredients thoroughly mixed in a porcelain dish. Gentle application of heat liberates the water of crystallization from citric acid and the mass tends to be coherent.
  Prolonged heating may result in complete evaporation of the released water leaving the product in the form of a dry lump which can not be rendered into granules. The coherent mass is transferred from the porcelain dish to an inverted sieve of suitable aperture size kept over a glazed paper.
  The mass is pressed through the sieve taking care to change the position of the sieve over the paper to prevent the formation of a lump of the sieved granules. The granules are dried in an oven taking care to regulate the temperature which should be generally kept below 80°C.
  The operation requires considerable skill and experience to obtain granules of uniform size and an elegant product. If necessary, the dry granules are passed through a sieve of appropriate size to break larger granules which result due to sticking of the sieved wet granules^–.
  The water of crystallization of the citric acid and the water from the reactions make the material coherent. Loss of weight occurs during granulation due to (a) evaporation from the damp mixture, and (b) loss of carbon dioxide. The losses constitute approximately one-seventh of the weight of powder used and must be allowed for when calculating the amount to be prepared.
  Chemical reaction
  3 NaHC0₃ + C₆H₈0₇.H₂0 = C₆H₅Na₃0₇ + 3 C0₂ + 3 H₂0 (Sodium bicarbonate) (Citric acid)
  2 NaHC0₃ + C₄H₆0₆ – C₄H₄Na₂06 + 2 C0₂ + 2 H₂0 (Sodium bicarbonate) (Tartaric acid)

  5. Cachets

  Cachet as a unit dosage form was very popular sometime back. Presently cachets are seldom used and have been replaced by capsules. Cachets, like capsules, can be easily filled and sealed at the dispensing counter.
  This dosage form holds larger quantity of the medication as compared to capsules. Since the cachets are made of flour and water they are easily damaged in handling. Further this dosage form offers little protection against light and moisture.
  Due to its size and shape a cachet is difficult to swallow. The process of filling is similar to that of capsules. The drug is placed in one of the two halves of the cachet, the upper half is then placed over it and pressed with the help of a suitable device.
  The flange of the upper plate is moistened carefully taking care not to wet it, with the help of a dampener. The sealing takes place due to the moisture between the flanges of the upper and the lower half and the pressure over the flanges. About 15 minutes are allowed for drying of the seal.
  After this time the middle portion of the cachet is slightly pressed to ensure complete sealing. In absence of a machine a pharmacist can improvise and use two bottles the mouths of which are broad enough so that flanges of the plates – upper and lower, when kept over the mouths of the bottles, just rest over them. The drug is transferred to one of the plates resting over the mouth of the bottle kept vertically on the working bench. The flange of the empty half resting over the mouth of another bottle is moistened with the help of a damp camel hair brush.
  The empty half of the cachet is then placed over the other half in which the medication is kept so that the flanges of the two halves are perfectly superimposed. The second bottle is then inverted and brought over the superimposed cachet and carefully put over the flange and pressed in position without disturbing the resting place of the cachet.
  This provides a good seal. Cachets can be dry-sealed also. These cachets however are of a different shape where the cap is pressed over the body of the cachet. A protruded stud is also provided to hold the upper and lower halves together.
  Like capsules, cachets are also expected to remain untouched by hand and one should use gloves while handling them. Since there are inherent losses of the drug in this operation also like that of powders and capsules, the quantities of each ingredient should be weighed for an extra powder over the number to be dispensed. The cachets are dispensed in wide-mouthed bottles of glass or plastic with a perfectly fitting cap. The patient should be instructed to keep the bottle securely closed
  Advantages:
  1) They can be made easily because no complicated machinery is required.
  2) They disintegrate quickly in the stomach
  3) The drug can be easily dispensed in cachets.
  4) Large dose of drug can be swallowed by using cachets.
  Disadvantages:                       
  1) They have to be soften before swallowing
  
  
  2) They are easily damaged
  
  
  3) They cannot protect drug from light and moisture
  
  
  4) The shell is very fragile
  
  
  5) Not suitable for filling the drug by large scale machinery
  6) They occupy more space and bulky for transportation                                                                     

POSOLOGY

POSOLOGY

Posology is derived from the Greek word posos meaning how much and logos meaning science So posology is the branch of medicine dealing with doses or quantity of drug required to produce therapeutic response.

The optimum dose of a drug varies from patient to patient. The dose is usually expressed as a range. The minimum dose or the lower limit of the dose is essential for eliciting an intended therapeutic response whereas the maximum dose or the higher limit of the dose is the amount of the drug substance that can be tolerated by an average individual. 

The pharmacist is much concerned with the maximum limit of the doses which, if exceeded, may cause untoward effects in the patient. The actual dose of a drug is to be decided by the prescriber depending on patient’s age, sex, symptoms, his medication history and the factors like tolerance, idiosyncrasy, route of administration etc.

Factors affecting dose of the drugs

1. Age: Human beings can be categorized into the following age groups:

·         Neonates:       From birth up to 30days.

·         Infant:            1 month to 2 years of age

·         Children:       2 to 12 years

·         Adolescents:  12 to 16 years

·         Adults:          More than 16 years

·         Geriatric (elderly) patients: above  60 years

In children the enzyme systems in the liver and renal excretion remain less developed. So all the doses of drugs given to children should be based on their age and preferably by body weight. In elderly patients the renal functions decline. Metabolism rate in the liver also decreases. Drug absorption from the intestine becomes slower in elderly patients. So in geriatric patients the dose is less and should be judiciously administered.

2. Sex: Special care should be taken while administering any drug to women during menstruation, pregnancy and lactation. Strong purgatives should not be given in menstruation and pregnancy. Antimalarials, ergot alkaloids should not be taken during pregnancy to avoid deformation of foetus. Antihistaminic and sedative drugs are not taken during breast feeding because these drugs are secreted in the milk and the child may consume them

3. Body weight: Dose of the drug can be calculating according to body weight. Obese patients, children and malnourished patients require less doses.

4. Route of Administration: Intravenous doses of drugs are usually smaller than oral doses, because the drug administered intravenously enters the blood stream directly.

5. Time of administration: Presence of food in the stomach delays the absorption of drug. The drug more rapidly absorbed from empty stomach. So the amount of drug is very effective when taken before meal

6. Environmental Factor: Daylight is stimulant enhance the effect of stimulating drugs and diminish the effect of hypnotics. Darkness is sedative. Hypnotic are more effective at night. The amount of barbiturates required to produce sleep during day time is much higher than the dose require in the night.

7. Emotional factors: The personality and behaviour of a physician may influence the effect of drugs especially the drug which are intended for use in a psychosomatic disorder. The female are more emotional than male require less doses.

8. Presence of disease: Drug like barbiturates chlorpromazine may produce prolongs effect in patients having liver cirrhosis. Streptomycin is excreted mainly by kidney may prove toxic if kidney is not functioning properly.

9. Accumulation: Drug excreted slowly may get accumulated in the body and produce toxic effects. Repeated administration of drug like digitalis, emetine and heavy metal may produce toxic effects.

10. Additive effect: When the total pharmacological action of two or more drugs administered together is equivalent to sum of their individual pharmacological action, the phenomena is called as an additive effect. For example, combination of ephedrine and aminophylline in the treatment of bronchial asthma

11. Synergism: When two or more drugs are used in the combination form, their action is increased. The phenomena is called synergism. Synergism is very useful when desired herapeutic result needed is difficult to achieve with a single drug e.g. procaine and adrenaline combination, increases the duration of action of procaine.

12. Antagonism: When the action of one drug is opposed by the other drug on the same physiological system is known as drug antagonism. When adrenaline and acetylcholine are given together, they neutralise the effect of each other.

13. Idiosyncrasy: An extra ordinary response to a drug which is different from its characteristic pharmacological action is called idiosyncrasy. The word idiosyncrasy has now been replaced by the term drug allergy. Penicillin & sulphonamide.

14. Tolerance: When an unusually large dose of drug is required to elicit an affect ordinarily produce by normal therapeutic dose of the drug, the phenomenon is termed as tolerance. eg. smokers can tolerate Nicotine

15. Tachyphylaxis: When certain drugs are administered repeatedly at short intervals, the cell receptors get blocked up (depletion of NT takes place) & pharmacological response to that particular drug is decreased. The decreased response cannot be reversed by increasing the dose .This phenomenon is known as tachyphylaxis. Eg.ephedrine in bronchial asthma.

16. Metabolic disturbances: Changes in water electrolyte balance and acid base balance, body temperature and other physiological factor may modify the effect of drugs. The absorption of iron from GIT is maximum if the individual has iron

deficiency anemia.

	Formulae for the calculations of doses. 1) Proportionate to age-
	1. Young’s formula:
	Age in years
	Dose for a child =   ------------------------	x	Adult dose
	Age in years +12
	2. Dilling’s formula:
	Age in years
	Dose for a child =   ------------------------	x	Adult dose
	20
	3. Fried’s formula:
	Age in months
	Dose for a child =   ------------------------	x	Adult dose
	150
	2) Proportionate to body weight-
	Weight of the child lb
	Dose for a child =   ------------------------	x	Adult dose
	150
	3) Proportionate to body surface area-
	Surface area of child
	Dose for a child =   ------------------------------		x   Adult dose
	Surface area of Adult

The average body area for an adult is = 1.73m²