PHA 317 MORE QUESTIONS
UV absorption spectroscopy can be used for detecting impurity in a substance. Which one of the following is correct about the presence of benzene as impurity in cyclohexane
Benzene can be detected in cyclohexane because it absorbs at 255nm while cyclohexane absorbs at 200nm
Chromophores and auxochromes can be differentiated on the basis of the following statement
Chromophores are a group of atoms which absorb efficiently radiation of a characteristic wavelength where auxochromes do not have their own characteristic absorption peak but maximizes the absorption capacity of the chromophores they are attached to
Splitting of a NMR peak occurs due to
Effect of neighboring protons
A matter that exhibits plastic flow, below its yield value would behave as
Elastic flow
Equilibrium is involved in the following processes playing an important role in pharmaceutics
Ionization of weak acidic or basic drugs Partition coefficient and lipid solubility of a drug Saturation solubility Diffusion and dissolution of drug
Solubility among isomers increase with
Decreasing boiling and melting point for liquid and solid repectively
Generally, absorption or transport of a drug unionized form through gastrointestinal membrane would be more than its ionized form
True
Generally, greater the value of partition coefficient, the higher the lipid solubility of the solute
True
Strong bases which are those with pKa values between 5 and 11 show ph dependence absorption
True
The greater the acidity constant the stronger the acid would be
True
The lower the pKa value for an acid, the greater hydronium ion concentration it would produce on being added to water
True
The polar surface area is defined as the sum of the Van Der Waals surface areas for the polar atoms, oxygens, nitrogens, and attached hydrogen atoms
True
The smaller the polar surface area of a drug the greater would be its oral absorption as well as penetration through the brain
True
The tallest signal in a mass spectrum of substance is called the base peak
True
The temperature can exert greater influence on the solubility of a drug if it is a weak acidic base
True
The transport of weak basic drugs across gastrointestinal membrane is influenced by ph only if their pKa values are within the range of 5-7
True
Viscosity is the reciprocal of fluidity
True
the rate of general acid and base catalysis is affected by concentration of undissociated buffer components in addition to hydronium and hydroxyl ion concentration
True
Following are some statements about phosphofluorescence
Phosphofluorescence is the energy released when triplet excited electrons return to the ground state Phosphofluorescence is a slower process and has a longer lifetime
The amount of force per unit area that is applied to a liquid or semi solid is called
Shearing stress
A concept of the partition coefficient is involved in following areas of pharmaceutical sciences
Preservation of oil water systems Drug action in non-specific sites Absorption and distribution of drugs throughout the body
a base catalyzed hydrolysis of an ester such as chloramphenicol palmitate can exhibit
a second-order kinetics only if the concentration of both - ester and base are changing, and a pseudo first-order kinetics if the concentration of the hydroxyl ion is maintained constant
prout-tompkins model best describes
a solid state reaction
The key factor in the viscoelasticity of blood are
both aggregation and deformability
dissolution rate can be increased by
increasing the diffusion coefficient
Ostwald viscometer is used for
liquids that flow relatively easily
Which is not a variable in the Noyes and Whitney equation
pH
Amber colored glass container is used to prevent the drug from
photolysis
Hydrogen peroxide is stored in dark container to prevent it from
photolysis
The plasma level of an orally administered tablet depends on
the rate of tablet disintegration and the rate of dissolution of the drug
Hixson-Crowell Cube Root Law is capable of determining dissolution rate when
the shape of the dissolving particle is uniform and does not change during dissolution
Following are some approaches to prevent the oxidative degradation of drug
using an initiation inhibitor such as EDTA, using colored glass containers, using chain breakers such as alpha tocopherol, using oxygen scavengers such as sodium metabisulfite and ascorbic acid
ampicillin degrades much faster in water than in alcohol because
water, being a high dielectric constant solvent, converts the neutral ampicillin into a charged transition complex
Which of the following are not correct according to the ph partition hypothesis of drug absorption
weak basic/ neutral drugs may be absorbed from the stomach bust basic drugs are not
The half-life of a drug in a solution is 30 minutes. What would be the concentration o the drug in the solution after 90 minutes?
12.5%
The pH range of the duodenum is
5-7
Tyrosine and tryptophan are most prominent amino acids capable of producing fluorescence when exposed to radiation of wavelength 190nm
False
1 centipoise is equal to
0.01 poise
What is the ratio of ephedrine to ephedrine HCL in the intestinal tract at ph 8
0.025:1
The time taken for 5% of a drug to decompose by first order kinetics is
0.051/k1
What is the normality of the 100mL solution containing 585 mg of NaCl in water
0.1N
Viscosity of an unknown liquid is 0.580 cp at 25 degrees celsius and the density is 0.858/cm cubed. What is the kinematic viscosity of the unknown liquid
0.676 centistrokes
What is the remaining concentration in mg/ml of a drug (initial concentration. a= 7 mg/ml) after a time equivalent to 3 half-lives assuming that the decomposition follows first order kinetics
0.875
What is the stomachs ph range
1-3.5
The initial concentration of active principle in an aqueous preparation was 5.0 * 10^-3 g/ml. After 10 months the concentration was found to be 4.2 * 10^-3 g/ml. The drug is known to be ineffective after it has decomposed to 70% of its original concentration. Assuming that decomposition follows first order kinetics, calculate the expiry date of the drug preparation.
20.5 months
What is the ph buffer containing 0.1-M acetic acid and 0.08 M sodium acetate
4.7
Below are some statements about BCS Class II drugs
Any interaction that increase drug solubility and dissolution rate in the gastrointestinal tract will exert a positive effect on the gastrointestinal drugs The absorption of this class of drugs is often enhanced in proportion to the fat content of the co-administered meal The antifungal drug griseofulvin and the cardiac glycoside drug digoxin are examples of Class II drugs
Drug-excipient interaction can be characterized by IR spectroscopy by
Appearance of a new peak Disappearance of a peak Shifting of a characteristic peak Broadening of a peak Alteration in intensity of a particular peak
Under which situation will the viscosity of oil increase
As temperature decreases
The shifting of peak of maximum absorption towards longer wavelengths in a spectrum is called
Bathochromic or Red Shift
The brush boarder coats the entire length of the stomach as well as small and large intestine which is consisted of
Both villi and microvilli
Below are some statements about BCS Class I drugs
Class I drugs are well absorbed and are effected by limited set of interactions that alter drug absorption Interaction that delay gastric emptying will delay absorption of these drugs Gastric emptying rate has significant effect on absorption of Class I drugs
The greater the pKa value for an acid, the greater hydronium ion concentration it would produce on being added to water
False
The greater the pKa value, the stronger the acid would be
False
There are two commonly used scales for measuring chemical shifts in an NMR spectroscopy called Delta and Tau scales which are related by
Delta = 10 - Tau Tau= 10 - Delta
Following are some statements about NMR spectroscopy
Different protons exist in different environemtns and thereby possess different magnetic field strength
Following are some statements about nuclear magnetic resonance spectroscopy
Different protons exist in different environments and thereby possess different magnetic field strength
Increasing which of the following will increase permeability of a molecule across a biological membrane
Diffusivity of the molecule
Systems which increase in volume when sheared are
Dilatant
The concept of partition coefficient applies only to
Dilute solutions
For Newtonian fluids, if the rate of shear is increased two times from its original value while the viscosity remains constant. What change could you expect in shearing stress of that liquid
Double it's original value
Knowledge and understanding of the equilibrium solubility of a drug is absolutely essential because it plays a critical role in
Drug discovery process Drug formulation process Selection of a dosage form for a drug Drug dissolution in the gastrointestinal tract Drug absorption
The most stable polymorph is always used for better clinical outcomes
False
Which one of the following facts are correct with respect to thixotropy
Exhibited by shear thinning systems, such as pseudoplastic and plastic liquids Can be defined as an isothermal and comparatively slow recovery, on standing of a material, of a consistency lost through shearing Behavior is useful for many pharmaceutical preps (suspensions)
A solution isoosmotic with blood would be isotonic too
False
Brush border consists of a 3mm thick uniform coating of mucopolysaccharide which is found lining the internal wall of the stomach only
False
Digestion and absorption of foodstuff occurs separately at different times in the small intestine
False
Drugs exhibiting polymorphism or pseudopolymorphism can be differentiated by using IR spectrophotometer
False
For newtonian fluids, the shearing stress decreases when the rate of shear increases
False
Molarity of a solution does not depend on temperature of the solution
False
Polymers in a solution generally exhibit plastic flow
False
Pseudoplatic flow has a yield value
False
Stronger bases like guanethidine are ionized throughout the gastrointestinal tract and tend to be well absorbed throughout the gastrointestinal tract
False
What will be the effect on flux if the concentration gradient of a drug across a membrane would increase two fold
Flux would double
Initial burst release is observed for which of the following matrix-based controlled drug release system
Hydrophilic or swellable matrix systems
Which of the following is NOT a physiological factor affecting the rate and extent of absorption of drugs through GI membrane
Hypophilicity of a drug
Following are some statements about the effect of neighboring electrons in NMR spectroscopy
If a proton is shielded by the induced magnetic field of the neighboring electrons, it will need greater strength of external magnetic field to flip its direction of orientation
We have 1:1 mixture of a polar and nonpolar solvent. If we add a non-polar drug to this mixture where would you find most of the drug
In the nonpolar solvent
Which of the following does NOT increase aqueous solubility
Increasing the length of a straight chain organic compounds
Below are statements about Class III drugs
Intestinal membrane absorption is the rate-limiting step in the absorption of class III drugs Class III drugs are better absorbed in the upper part of the small intestine Any meal co-administered with class III drugs decrease their absorption proportionately to fat content of the meal
Generally, octanol is used as organic phase for determining partition coefficient. However, what other alcohol is also used for this purpose
Isobutanol
Although NMR spectroscopy has instrinsically low sensitivity, it has many advantages show below:
It is a non-destructive technique Many samples present in a solution Minimal or no sample preparation is needed
Phenobarbital is a weak acidic drug. What would be its solubility in solvents A (ph7), B (ph8), C (ph10)
It would dissolve more in solvent C than A or B
For nitroglycerine (NTG), it is important to counsel patient not to remove tablets from packaging until they actually use the tablets. This is due to what characteristic of NTG?
NTG is susceptible to loss by sublimation at room temperature
If the shearing stress is directly proportional to the rate of shear the liquid exhibits a
Newtonian flow
Benzene is a colorless organic solvent, but nitro benzene is pale yellow liquid while p-hydroxynitrobenzene is bright yellow. The shift in the appearances of color for these substances can be explained on the basis of concept of chromophores and auxochromes. Select the correct example of each
Nitro group is a chromophore and hydroxyl is a auxochrome
Minocycline and doxycycline have greater log p value than other tetracycline. Which of the following statements is/are correct about them
Only minocycline and doxycycline pass through blood brain and blood ocular barriers while other tetracycline does not
Which one of the following properties does not affect absorption of a drug from gastric lumen
Optical rotation
Indicate which of the following is correct about osmosis
Osmotic pressure is proportional to number of ions or molecules of solute dissolved in solvent
Thixotropy is a special characteristic that is exhibited by shear thinning systems, such as
Plastic and Pseudoplastic
1g of a drug s soluble in 10.50 L of water. Which one of the following correctly define its solubility as per USP definition
Practically insoluble
Dissolution testing is conducted by manufacturers under what condition
Sink
Plastic flow is associated with
Suspensions
Which of the following equations predicts the stability of a drug at room temp from experiments at accelerated condition at high temp
The Arrhenius Equation
Below are some potential applications of UV visible spectroscopy
The concentration of a protein solution can be calculated if its amino acid sequence and MW is known The presence of RNA as an impurity in a DNA sample can be determined by the ratio of its absorbance at 260nm and 280nm The extent of ionization of an acid can be easily determined
The Beer Lambert Law is the basis for deriving quantitive information from an absorption spectrum. Which of the following is the correct description of the constant in the mathematical equation representing the Beer Lambert Law
The constant K is called molar absorption coefficient if unit of concentration (c) is mole/liter The constant K is called specific absorption coefficient if unit of concentration (c) is gram/liter
Although NMR spectroscopy has intrinsically low sensitivity, it has many advantages as shown: The following are some of the potential applications of NMR spectroscopy:
The detection of decrease in phosphocholine level tumor cells The detection of decrease in urate oxidase level may indicate efficacy of antimicrobial agents against aspergillus nidulants The detection of decrease in urine hippurate and/or increase in plasma alanine level may indicate an increase in hepatic sensitivity
The biological membrane is covered on both sides by lipid layers which are interrupted by water filled pores. Which statement is correct
The radius of the aqueous pores on biomembrane is approximately 4 angstrom, therefore any hydrophilic drug smaller than 4 angstrom can get transported through easily
Which one of the following is not affected by partition coefficient
The passage of water through biological membranes
Digoxin is poorly soluble drug. Therefore, its physical forms such as particle size would have a significant effect on it therapeutic outcomes
True
When a drug is administered in a dosage form such as tablet, capsule, or suspension, the rate of absorption across the biological membrane frequently is controlled by
The slowest step involved in disintegration, dissolution, and absorption
How does temperature affect solubility
The solubility increase with higher temperatures for endothermic solids
There is evidence for the existence of diumal cycle of gastric acidity in humans. Which is correct in this regard
The stomach contents during nighttime are generally more acidic with approximate ph of 1.3
Which one of the following statements is correct about diarrhea
There is a co-transport system unaffected by diarrhea causing microorganism, which transports Na+ ions to blood only when glucose is also present
Fluorescence spectroscopy could be many folds more sensitive than UV-visible spectroscopy
True
Which one of the following is the most desirable flow characteristic for a dosage form design
Thixotropic flow
Cup and Bob type of viscometer may be used for gels and pastes
True
Following are some of the potential applications of mass spectroscopy
Useful in proving the identity of a compound and establishing its structure Provides an exact molecular weight and molecular formula of a substance
The arrhenius equation of rheology expresses the relationship between
Viscosity and temperature
A typical IR spectrum can be broadly divided into two parts
Wave number range of 1450-600 cm is the fingerprint because unique for a specific substance Wave number range of 4000-1450 cm called the frequency region because unique for a specific functional group present in a substance
100mL of water was added to a 200mL solution. When the total volume was measured, it was found only 298mL even if there is no loss of material during mixing. Is this a real solution
Yes
The area under a peak NMR spectrum indicates the # of protons representative of that peak
Yes
An increase in temp by 10 deg. Celcius near room temperature is known to cause
a 2-4 fold increase in reaction rate for many reactions
The driving force for processes to occur is
all systems spontaneously move towards lower free energy and higher entropy
In a zero order reaction what is the unit of K0
concentration/time
The Lineweaver-Burke equation for an enzymatic reaction is useful for
determining the constant Km in Michaelis Menton equation and determining the constant Vmax in Michaelis Menton equation
the release of a drug from matrix system occurs by
diffusion from the matrix system and erosion of the matrix system
It is conceivable for a reaction to have zero or fractional molecularity
false
The rate of specific acid and base catalysis is affected by concentration of undissociated buffer components in addition to hydronium and hydroxyl ion concentration
false
The rate of dissolution when surface area exposed to the solvent/medium remains the same is called
intrinsic dissolution rate
Which of the following is NOT a characteristic of solid state reaction?
it happens in a homogenous medium
The hydrolytic degradation of acetylsalicylic acid in its aqueous suspension follows which kind of kinetic
pseudo zero-order
Sodium salicylate is capable of _____ at the diffusion layer and displays a greater rate of dissolution under conditions of more acidic simulated gastric fluid than salicylic acid
supersaturation
The rate or speed of a process can be defined by
the rate at which the concentration of a species undergoing the change decreases, and the rate at which the concentration of the resulting species increase with time
In a zero order reaction
the rate of decomposition is independent on the concentration of any of the reactants
In a study of the hydrolysis of a drug in aqueous solution a plot of logarithm of the amount of the drug remaining (as ordinate) against time (abscissa) is linear
the unit of k is concentration-1time-1
For a single step (elementary) reaction, the molecularity and order are the same
true
Generally, surface area does not remain constant throughout the dissolution process
true
Insoluble polymers such as ethyl cellulose, methylmethacrylate, or polyvinvyl acetate are used for making inert matrix-based extended drug release systems
true
It is not conceivable for a reaction to have zero or fractional molecularity
true
