Climate Zone IVb: why Guyana rejects drugs not made for its heat

The rule: made for Zone IVb or not admitted

Medicines are tested for stability under the climate they are meant to be sold in. On 30 November 2020 the Government Analyst – Food and Drug Department (GA-FDD) spelled out what that means for Guyana. Manufacturers set a product's stability, shelf life and expiry date for a climatic zone, and quality, efficacy and safety "cannot be guaranteed if it is sold outside the intended zone"¹². The department listed the zones: I temperate (Canada, Germany), II Mediterranean/subtropical (Chile, Turkey), III hot/dry (Chad, Iraq), IVa hot/humid (Jamaica, Pakistan) and IVb hot/very humid, which includes Guyana, India and Brazil¹²³.

Its conclusion was blunt. Only medicines "which have undergone the requisite stability testing" and are intended for Zone IVa or IVb countries may be imported; declarations of the intended zone must be clear to the department or stated on the label; and waivers "will be prohibited"²¹. Products for Guyana's market must also be labelled in English under the Food and Drugs Act of 1971 and its 1977 Regulations¹³. The department added that it had become an accredited Conformity Assessment Body and would give greater scrutiny to medicines from outside Zones IVa and IVb¹³.

The 2020 seizures

The warning came with action. Inspectors visited more than 11 pharmacies in Georgetown and outlying areas and removed medicines labelled in Turkish and made for a different climatic zone from about 10 of them¹²³. No pharmacy, product or manufacturer was named¹³. The legal basis is broad: section 25(1)(e) of the Food and Drugs Act, Chapter 34:03, lets the Minister make regulations on the "preserving, packing, storing and testing" of drugs to prevent injury to health, and section 22 lets inspectors sample customs entries and refuse admission to any drug whose sale would break the Act⁵. The same year the GA-FDD reported that about 30 % of 36 market samples tested with CARPHA were substandard¹³.

What WHO's stability guideline actually requires

The reference document is WHO's guideline on stability testing of active ingredients and finished products, published in 2018 as Annex 10 of Technical Report Series No. 1010⁴. It records how several hot, humid countries chose up to 30 °C and 75 % relative humidity as long-term test conditions to build in a larger safety margin, and it defines Zone II as 25 °C/60 % RH, Zone IVa as 30 °C/65 % RH and Zone IVb as 30 °C/75 % RH⁴.

Its Appendix 3 is the practical part for importers. A product approved in a Zone II country with a label such as "Store at 15 °C to 30 °C" (USA, Canada), backed only by Zone II and accelerated data, should carry the WHO-recommended statement "Do not store above 25 °C. Protect from moisture" when distributed in Zone IV⁴. Only a product also shown to be stable at Zone IVb conditions earns "Do not store above 30 °C"⁴. In other words, a box bought in Miami or Toronto is not automatically labelled for a Georgetown pharmacy shelf.

Peptide drugs: a cold chain on top of the climate

Peptides and proteins are more fragile than most tablets. A review of protein pharmaceuticals describes both chemical and physical instability, which interact with each other, as the central formulation problem⁸. That is why many peptide injectables are not zone-labelled room-temperature products at all, but cold-chain products. The US label for Ozempic (semaglutide) tells users to store new, unused pens in the refrigerator at 2 °C to 8 °C; a pen in use may be kept for 56 days at 15 °C to 30 °C or refrigerated; it must not be frozen, and should be kept away from heat and out of the light⁶.

Insulin, the oldest peptide drug, shows both the risk and the margin. In 2018 the Ministry of Health showed the Department of Public Information a 40-foot container of insulin kept in a cold storage container at its Diamond, East Bank Demerara facility¹⁰. A 2021 study logged temperatures swinging between 25 °C and 37 °C in a refugee camp in northern Kenya and found that several insulin formulations kept there through a four-week in-use period met pharmacopoeia standards, with bioactivity identical to refrigerated samples⁷. The authors concluded insulin can be kept at such oscillating temperatures for the usual four weeks of use⁷. That evidence covers in-use insulin, not unopened stock or other peptides.

Suitcases and the cold chain

The informal trade breaks both rules at once. In May 2024 Stabroek News reported that Ozempic, then unregistered in Guyana, was being dispensed through medical spas, bottom-houses and a suitcase trade; one seller told the paper the medication is "normally transported via cold storage"¹². In April 2026 HGP Nightly News, reporting on President Irfaan Ali's warning about tirzepatide (Mounjaro), cited reports of suitcase traders bringing the drug in unregulated, with a risk of counterfeit or "non-refrigerated" products⁹. WHO notes that long, complex supply chains with multiple intermediaries increase the risk of tampering and substitution¹¹. A pen that sat in a hot hold or a car for hours can look exactly like one that did not.