Frequency of Medicines for Infants Under 1 month

During the first month of life absorption, metabolism and excretion in a baby are not yet fully developed. For this reason, the frequency of medicine dosing is based on gestational age and not on the characteristics of the medicine.

Table 1 below gives the frequency of dosing for all medicines (except gentamicin - see table 2) and is referred to in the therapies that follow under Neonatal Infections.

Table 1: Frequency of dosage by gestational age: (NB not for gentamicin - see table 2 below)

Gestational age ≥ 37 weeks (term baby)
First two days	2 doses per 24 hours
3 days to 2 weeks	3 doses per 24 hours
> 2 weeks	4 doses per 24 hours
Gestational age < 37 weeks (pre-term baby)
First week	2 doses per 24 hours
1-4 weeks	3 doses per 24 hours
> 4 weeks	4 doses per 24 hours

For example: Benzylpenicillin dose 100,000u/kg/dose (0.1MU/kg). Thus, a 2kg pre-term baby 5 days old would receive 200,000u benzylpenicillin every 12 hours, whilst a 2kg term baby 5 days old would receive 200,000u every 8 hours.

Table 2: Gentamicin dosages:

Premature or full-term neonates
Weight	Age	Dose	Frequency
less than 1000gm	28 weeks	5mg/kg	Once every 48 hours for first two weeks, then once every 36 hours.
1000g to 2000g		5mg/kg	Less than 1 week old once every 48hours more than >1-week-old once every 36 hours
More than 2000g	Less 1 week old 1 week and above	4mg/kg	Once every 24hours Once every 24-48hrs*

*This dosing is as it appears in the Zimbabwe STG, doctor should review appropriateness of frequency prior to prescribing