TDM UPDATES 2021

Nur Farhanah binti Ahmad Rifa’i

Pegawai Farmasi UF48

CLINICAL PHARMACOKINETIC SERVICES (CPS)

• Also known as Therapeutic Drug Monitoring (TDM) for drugs with narrow therapeutic range
• Currently shifting towards utilizing PK/PD model in predicting individualized treatment response

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CLINICAL PHARMACOKINETICS PHARMACY HANDBOOK (CPPH)

• Published in 2019
• Available at https://www.pharmacy.gov.my/v2/sites/default/files/document-upload/clinical-pharmacokinetics-pharmacy-handbook-ccph-2nd-edition-rev-2.0.pdf

CPS IN HTJS

Operating Hours:

Monday – Friday (excluding public holidays)

8.00 am – 5.00 pm

Extension number:

4405 (TDM)

AOH, Weekends & PH (Toxicity cases ONLY):

4027 (In-Patient Pharmacy) or 4099 (Emergency & Trauma Pharmacy)

PROSES KERJA KES TDM

LIST OF DRUGS MONITORED

• Amikacin*
• Carbamazepine
• Cyclosporine*
• Digoxin
• Gentamicin
• Lithium*
• Methotrexate*
• Paracetamol

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• Phenobarbitone*
• Phenytoin
• Salicylate
• Sirolimus*
• Tacrolimus*
• Theophylline*
• Valproic Acid
• Vancomycin

*outsource to other facility

OUTSOURCED SAMPLE ANALYSIS

Samples are sent to Hospital Kuala Lumpur (HKL) every Tuesday and Thursday (excluding public holidays).

Blood samples together with completed TDM forms must be sent to biochem lab by 3.00 pm on Monday and Wednesday for packing by lab technicians.

UNDERSTANDING SAMPLING TIME

• Pre: taken before dose (<30 minutes before dose)
• Post: taken after dose
• Random: taken regardless of dosing time

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PROCESS OF BLOOD SAMPLING

• Volume
• Adult – 3ml
• Paediatric – 1 - 2ml

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• Specimen tube
• Plain tube without gel (red cap) *started on 15^th Feb 2021

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• EDTA tube (purple cap) for CSA, Sirolimus and Tacrolimus

HOW TO FILL IN THE TDM FORM?

Columns to fill in for Pharmacist:

1. Patient profile (including height and weight)
2. Diagnosis/ clinical summary
3. Patient condition: tick where applicable
4. Indication
5. Latest lab results: put (-) if not available
6. Concurrent medications: same group eg: concurrent antiepileptics, antibiotics etc
7. Present dose regimen, date and time dose started
8. Infusion rate: particularly important for antibiotics
9. Suggested sampling time
10. Pharmacist’s signature & stamp

TDM POOL

• TDM Pool consists of:
• Nur Farhanah
• Ong Wei Yan
• Thong Kai Leng
• Wedad Nasuha
• Sohaila
• Passive on call over weekends and public holidays
• Handles scheduled TDM cases* and as point of reference for TDM referrals

*wards under department of Anaesthesiology (ICU, HDW 1, HDW 2); Nephrology (1E) or Paediatrics (NICU, PICU)

CPS AFTER OFFICE HOURS (AOH)

Hi, I would like to refer a case for TDM?

WHAT SHOULD YOU ASK?

Patient’s details

• Name
• RN/ IC no.
• Ward/ bed
• Weight

Medication

• Dose and frequency
• Duration
• Last dose taken
• Compliance

Lab Investigations

• Renal function
• Antibiotics -treatment or empirical; synergistic?

TDM

• Indication- routine or suspected toxicity

Others

• Doctor’s name
• Extension number

WHAT TO DO NEXT?

ROUTINE MONITORING

• Check the prescribed dose *correct the dose if needed
• Recommend sampling date and time (schedule for the next working day) or consult TDM pool pharmacist on-call
• PRP (counselling call 9am – 2pm) to give appointment in ward
• After 2pm, for doctor/nurse need to collect the form at pharmacy

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• Supply TDM form (available in A&E pharmacy and inpatient pharmacy)
• Guide the doctor on how to fill the TDM form (sampling time, sign and stamp)
• Check WinPath for result
• Provide recommendation based on TDM level
• Fill in TDM Toxicity Registry

SUSPECTED TOXICITY

PROSES KERJA KES DISYAKI TOKSIK (SUSPECTED TOXICITY)

TDM TOXICITY REGISTRY

Available in TDM folder at IPD and A&E Pharmacy

QAP 2: All TDM results for suspected toxicity cases must be informed to the doctor within 1 hour after result is released.

WINPATH WARD ENQUIRY

CONVERSION FACTORS

mcmol/L to mg/L = ÷ conversion factor

TDM RESOURCES

In-Patient Pharmacy

A&E Pharmacy

VANCOMYCIN

• Latest consensus guideline 2020 (IDSA, ASHSP, PIDS, SIDP) recommends targeting AUC-24 of 400 – 600 for serious infections caused by MRSA instead of utilizing trough-only monitoring with target level of 15 – 20 mg/L
• Sampling: pre and post (1 hour after infusion completed) or random for ESRF patients
• Loading dose: 20 – 30mg/kg (actual body weight, not exceeding 3g)
• Maintenance dose: 15 – 20mg/kg/dose or refer CPPH for dosing guide (use adjusted body weight for obese patients)
• Dilution: maximum concentration : not to exceed 5 mg/mL; for fluid restriction patient, maximum concentration: 10 mg/mL
• Infusion: at least 60 minutes or a maximum infusion rates of 10 mg/min, whichever is longer

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GENTAMICIN

SINGLE DAILY DOSING

• More rapid bacterial killing by achieving high peak
• Possible less nephrotoxic event
• Careful in: pregnancy, ascites, burn, gram positive infections (synergy), CrCl <30ml/min, dialysis, neutropenic patients, hemodynamically unstable, cystic fibrosis
• Dose: 4 – 7mg/kg OD.
• Use adjusted body weight for obese patients
• Sampling: post 2H and post 6H

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CONVENTIONAL DOSING

• Given in patients excluded from SDD criteria
• Usual dose: 1.5 – 2mg/kg/ dose, frequency determined by renal function
• Sampling: pre and post

TAKE HOME MESSAGE

QAP 2: All recommendations for suspected toxicity cases must be informed to the prescriber within 1 HOUR of result released from lab.

All PRPs please come for pass over before counseling call (weekend and PH) and tagging especially for those who has not trained under TDM before

Please pass over all TDM referrals or cases to the next on call PF/ PF TDM pool

THANKS!