Question
Outline how these drug administration methods affect bioavailability.
Oral:
Intravenous:
Answer/Explanation
Answer:
Oral:
low/lower «bioavailability» AND drugs pass through digestive system «and
breakdown»
Intravenous:
high/higher «bioavailability» AND «more» direct route to bloodstream
Question
Drugs are commonly prescribed by medical professionals to treat illness.
(a) State two different drug administration methods.
(b) Explain how aspirin works as a mild analgesic.
(c) Deduce the structural formulae of the missing reactant A and product B in the synthesis of aspirin from salicylic acid.
(d) State one advantage and one disadvantage of prescribing opiates to patients.
Advantage:
Disadvantage:
Answer/Explanation
Answer:
(a) Any two of:
oral
inhalation
topical/applied to the skin
parenteral/injection
suppositories
eye/ear drops
(b) interferes with pain at source «of injury»
prevents release of prostaglandins/substances causing swelling/pain
(c) ALTERNATIVE 1:
A: \(CH_3COOCOCH_3\)
B: \(CH_3COOH\)
ALTERNATIVE 2:
A: \(CH_3COOH\)
B: \(H_2O\)
ALTERNATIVE 3:
A: \(CH_3COCl\)
B: HCl
(d) Advantage:
strong/severe/surgical pain relief
OR
stops coughing reflex
OR
fast action
Disadvantage:
addiction
OR
constipation
OR
tolerance «leading to overdose»
Question
This question is about antiviral drugs.
Oseltamivir, used for the treatment of severe flu, is inactive until converted in the liver to its active carboxylate form.
a(i)Draw a circle around the functional group that can be converted to the carboxylate by hydrolysis.
a(ii)Suggest a reason for using a phosphate salt of oseltamivir in oral tablets.
b. Anti-HIV drugs, such as zidovudine, often become less effective over time.
Explain the development of resistant virus strains in the presence of antiviral drugs.
▶️Answer/Explanation
Markscheme
a(i)
Note: Accept circles that include the alkyl side chain.
a(ii)more soluble «in water» $
b. viruses undergo «rapid» mutation $
mutation causes a change in viral protein
OR
Note: Accept “rapid reproduction “allows resistant viruses to multiply»”.