Drug Information Enquiry

Question 1

List the seven steps in the systematic process for a DI request.

Answer 1

1) Secure enquirer’s demographics
2) Obtain background information
3) Determine & categorise the ultimate question
4) Develop search strategy with appropriate references
5) Synthesise, evaluate & assess retrieved information from references
6) Formulate & provide response
7) Document & follow-up

Question 2

What are some key pieces of requestor demographic information you should retrieve upon receiving a DI enquiry?

Answer 2

At the start:
1) Name + Designation
2) Status (i.e. for Dr: HO < MO < Registrar < Associate Consultant < Consultant)
3) Department / Clinic (e.g. ID, Ortho, Onco etc.)

Before concluding:
4) Expected time to receive response by (usually 15-20 min)
5) Contact number of requestor / clinic to follow up

Question 3

In what types of DI enquiries should you probe for the patient’s profile during the retrieval of background information?

Answer 3

1) Pregnancy & Lactation
2) Drug Interactions (DDI)
3) Adverse Drug Reactions (ADR)
4) Dosing & Choice of Therapy
5) Drug Safety (e.g. Allergy)

Question 4

When the patient profile is required in a DI enquiry, what are some key pieces of information you will need to process the enquiry?

Answer 4

1) Age, gender, weight and/or height (if applicable)
2) Any renal/hepatic impairment?
- Renal: CrCl (if SCr, calculate using Cockgraft-Gault eqn), CAPD/HD if on dialysis
- Hepatic: Child-Pugh’s score, ALT, AST etc.
3) For Abx: Empiric / culture-directed Tx? Date of results? Microorganism identified? Hospital- (nosocomial) or community-acquired? Sensitivity?

MAC:
4) Medications: Any concurrent meds / OTC / TCM / herbs / supplements?
5) Allergies / Intolerances: Reaction Hx, onset, last observed, characteristics (to determine real vs pseudo-allergy), severity?
6) Conditions: Any other medical conditions?
- Possible drug-Dx interactions

Question 5

What are some pieces of background information you require when faced with an availability/identification DI enquiry?

Answer 5

1) Reason for enquiry? (poisoning? ordering? allergy?)
2) Name of drug (spelt out & read back)?
3) Strength & dosing frequencies?
4) Country of origin?
5) When & where did pt. obtained medication from?
6) Dosage formulation & appearance characteristics?
7) In loose form / blister packs?
8) Indications?

Question 6

What are some references you use in your search strategy to develop a response for an availability/identification DI enquiry?

Answer 6

1) MIMS Online
(+) ID of brands & supplements with pill identifier
(+) LASA drugs can be searched using in-built Google search engine
(+) Useful to ID overseas products
(-) Pharma companies need to pay, thus not all encompassing

2) Mediview
(+) ID of commonly used drugs via images

3) Martindale / Micromedex Drug ID / Lexicomp
(+) Useful for ID overseas products
(-) Formulation differs between brands & countries outside of SG

4) Institutional Formulary List

5) HSA PRISM
(-) Requires correct spelling of generic drug name
(-) Covers only registered medical products

6) Google (LAST resort)

Question 7

What key elements should you include in your response to an availability/identification DI enquiry?

Answer 7

1) Repeat & contextualise requestor question (i.e. F2F/audio-only call/video call etc.)

2) Generic & brand name of drug
- Audio call: SPELL the name in full with country names to assist
- F2F: Provide physical label for spelling check

3) Uses / Indications of drug

4) Available formulation & strength of drug + cost
- Provide more cost-effective generic options if available

5) Type of access: POM/POME/P-only/GSL?
- Any special restrictions on access to patients?
- e.g. require a specialist to prescribe etc.

6) If unavailable, provide alternatives.
- Assess necessity & replacability first w/ other options in formulary list/NDF
- Refer to other pharmacies to retrieve product or nearest GP clinic / polyclinic to obtain Rx for dispensing
- Consider alternatives to ensure continuity of care (e.g. check if sufficient tablets/doses before next follow-up appt.)
- Pt. profile required when shifting from Availability to Choice of Therapy DI enquiry.

7) End with contact information for follow-up enquiry

Question 8

When is obtaining two patient identifiers important during DI enquiries?

Answer 8

Handover-takeover of information that involves patient profile

Question 9

How many mL of insulin are 100 units equivalent to?

Answer 9

1 mL

Question 10

What volumes of IV bulk infusion containers are available in SG?
Which diluent is only available in such containers for final dilution for IV infusion administration?

Answer 10

50 mL, 100 mL & 500 mL
Dextrose 5% in water (D5W)

Question 11

What is the volume capacity of a standard IV drip burette used for IV infusion?

Answer 11

100mL - 120mL

Question 12

Which patient populations should fluid restrictions be considered?

Answer 12

Heart, renal, liver failure pt.
Neonates

Question 13

How does one calculate the daily fluid requirement of an individual?

Answer 13

Fluid requirements/day:
0 - 10 kg: 100 mL/kg
10 - 20 kg: Add 50 mL/kg
> 20 kg: Add 20 mL/kg

e.g. 3 kg child requires 300 mL/day, but 50 kg adult requires (1000 + 500 + 600 =) 2100 mL/day.

Question 14

What are some considerations to bear in mind when administering IV drugs via bolus or infusion?

Answer 14

1) Max concentrations, osmolarities & pH of central lines > peripheral lines due to rapid blood flow
2) Risk of phlebitis increases with increasing drug concentrations, esp. for peripheral lines
3) Dilution of drugs formulated with co-solvents can cause PRECIPITATION (e.g. phenytoin) if diluted in large volumes & should be avoided for risk of embolism.

Question 15

What are the common parenteral diluents available in SG?

Answer 15

1) Sterile water for injection (SWFI)
2) 0.9% w/v NaCl (i.e. normal saline - NS)
3) Dextrose 5% in water (D5W)

Question 16

Parenteral preparations can mix with biological compounds (e.g. blood products) and total parenteral nutrition. True or false?

Answer 16

False!!
Parenteral products SHOULD be run in DEDICATED lines, SEPERATE from biological products & TPN, using multiple lumens of central lines.

Question 17

If Drug X & Drug Y are compatible at Y-site administration after cross-referencing from reliable sources, are they also compatible as an admixture? Why?

Answer 17

No!

If two drugs are compatible as admixture, we can extrapolate to be compatible at Y-site administration.
- However, if two drugs are ONLY compatible at Y-site administration, we CANNOT extrapolate to admixture/additive compatibility.
- Exposure of both drugs to each other is longer as admixture than mixed at Y-site, thus if stability is maintained at longer periods of exposure, the same should hold true for shorter periods as Y-site administration.

Question 18

Which policy is adopted heavily as part of the SOP of sterile preparation compounding in SG?

Answer 18

USP General Chapter 797 Pharmaceutical Compounding - Sterile Preparations

Question 19

With reference to SGH, elaborate on the framework* adopted in determining the stability of unfinished but reconstituted IV preparations (e.g. ampoules/vials).

*Note that the framework differs from institution to institution!

Answer 19

1) Is it a “multi-dose” vial / preparation?
(+) Follow manufacturer’s recommended shelf-life since preservatives are present to reduce microbial growth upon opening in aseptic conditions.
(-) Proceed to next qn.

2) Is it an ampoule / labelled as “single-dose”?
(+) Discard immediately after reconstitution.
(-) Proceed to next qn.

3) Is it stable for at least 24?
(+) Use within 24 h; store in fridge at 2-8 deg C ONLY if there is stability data to reduce microbial growth potential and slow hydrolysis.
(-) Use it within stated stability time-frame provided by PIL.

Question 20

Describe the calculations taken to determine the final volume of Drug X for administration via IV infusion / bolus, for a fluid-restricted patient.
- Treat as if Drug X must be further diluted from the reconstituted vial before it is ready to be administered.

Answer 20

1) Determine volume of initial diluent required to reconstitute a concentrated stock solution of Drug X
2) Determine the concentration of Drug X found in the vial of reconstituted concentration stock solution.
3) Withdraw volume (= dose) required from concentration stock solution of Drug X to be administered for further dilution
4) Determine the final volume of Drug X diluted in final diluent to be administered by dividing the volume withdrawn from concentrated stock solution by max. concentration of Drug X that can be administered into IV central / peripheral lines.
- Non-fluid-restricted pt.: Use appropriate conc. based on PIL
- Check Teddy Bear Book for max conc. & x-ref with Trissels
5) To find the volume of final diluent required, subtract volume in Step 3 from volume found in Step 4.

• Concentration = Dose / Volume
  Volume = Dose / Concentration

Question 21

What are some pieces of background information you require when faced with a parenteral administration DI enquiry?

Answer 21

1) Name of drug (spelt out & read back)?
2) Route of administration (e.g. IV/IM etc?), dose & frequency?
3) Indications?
4) Does SN have the drug with her now?
5) Brand / manufacturer’s name & strength?
6) Fluid / diluent restrictions?
- Fluid restricted: Use max possible conc.
- T2DM: Recommend using NS as diluent.
- Hyper-Na+: Recommend using D5W as diluent
7) Central / peripheral line available? No. of lumens? Y-site required?

Question 22

What are some references you use in your search strategy to develop a response for a parenteral administration DI enquiry?

Answer 22

1) Product Information Leaflets (PILs)
(+) Top choice as recommendations account for particular formulations & unique excipients

2) Trissels (ASHP Injectable Drug Information Guide)
(+) Each drug monograph contains a section on parenteral preparations.

3) Teddy Bear Book (Paediatrics Injectable Drugs)
(+) Particularly useful for fluid-restricted patients as max concentrations allowed for various drugs are included.
(+) Paeds generally tolerate less fluid since their tiny blood vessels are vol. AND conc. dependent, thus able to extrapolate to fluid-restricted adults with more competent vascular structure

4) Lexicomp / UpToDate, under “Administration: IV”
(-) Limited information

5) Goharl’s Intravenous Medications (LAST resort)

Question 23

What key elements should you include in your response to a parenteral administration DI enquiry?

Answer 23

1) Reconstitute the (drug & brand name) (strength) mg vial with ___ mL of initial diluent to prepare a concentrated stock solution.
- Shake well to dissolve powder until a clear solution is achieved.
2) Withdraw ___ mL (= required dose in mg) from the concentrated stock solution in the stock vial.
3) Top up to (final volume for administration) mL with final diluent for administration. Shake well for even dispersion.
- Check if there is any precipitation or leaks throughout the reconstitution and preparation. If present, discard and reconstitute with another fresh vial.
4) Run Drug X over ___ mins/hours (based on PIL’s recommended rate of administration).
5) If giving only a portion of a vial:
- Inform the nurse how long can the remainder of the vial be kept, or should be discarded based on framework.
- Dependent on stability, sterility & recommended shelf-life of product based on PIL.

Question 24

What are some pieces of background information you require when faced with a parenteral admixture compatibility DI enquiry?

Answer 24

1) IV drugs involved? Name of drug (spelt out & read back)?
2) Dose & frequency?
3) Is one of the drugs currently running in pt.?
- In what drug concentration and diluent?
4) Admixture or Y-site administration?
5) Central / peripheral line available? No. of lumens? Y-site required?

Question 25

What are some references you use in your search strategy to develop a response for a parenteral admixture compatibility DI enquiry?

Answer 25

1) Trissels (ASHP Injectable Drug Information Guide)
(+) Each drug monograph contains detailed compatibility tables stating drug concentrations & diluents used, as well as conditions used in referenced stability studies.

2) Trissels 2.0 @ Micromedex
(-) Possible discrepancies between this & ASHP due to retirement of Trissel as lead editor from ASHP

3) King’s Guide
4) Lexicomp (“Compatibility”)

5) Product Information Leaflets (PILs) from HSA PRISM
(-) Information available limited as most manufacturers will not invest in complex compatibility studies with other drugs.

6) Article Search from PubMed or CINAHL (LAST resort)

Question 26

What key elements should you include in your response to a parenteral admixture compatibility DI enquiry?

Answer 26

1) Compatible or incompatible?
- Compatible: What concentrations & diluents used?
- Incompatible: Due to precipitation or chemical degradation?

2) If compatibility data does not exist at all, or no good data at appropriate concentrations, err on medication safety side in general to avoid combination.

3) Consider possible DDI, esp. if one drug is a potent CYP450 inhibitor!!