Generic Medicines: Quality, Cost and Common Misconceptions

Most pharmacy staff have heard a patient ask whether a cheaper generic will work as well as the brand. The honest answer depends on two separate questions. The first is whether the product was shown to be equivalent to the originator before it was registered. The second is whether the pack in the patient’s hand is genuine and meets its quality specifications.

What “generic” means

The World Health Organization (WHO) describes a generic, in definitions reproduced by the Generics and Biosimilars Initiative, as a pharmaceutical product that is usually intended to be interchangeable with the originator brand, made without a licence from the originator and marketed after patent or other exclusivity rights expire. WHO also uses the term “multisource product” for the same idea.

The generic name is the International Nonproprietary Name (INN), a unique public name for each active ingredient. A brand name belongs to one manufacturer, while the INN is shared by every product containing that ingredient.

Two terms do most of the work in this topic. Pharmaceutical equivalence means identical amounts of the same active ingredient, in the same dosage form and route of administration, meeting standards of strength, quality, purity and identity. Bioequivalence goes further and compares how the body handles the two products.

How a generic is shown to work like the original

The WHO Prequalification of Medicines programme states that a multisource product must meet the same standards as the originator. The manufacturer must give assurance that the product is clinically interchangeable with the innovator product or a designated comparator, meaning it is therapeutically equivalent or bioequivalent.

In practice, bioequivalence means the generic must show the same rate and extent of absorption as the originator. As Colgan and colleagues explain in BMJ Open, a generic may still differ in colour, size, shape and inactive ingredients.

A bioequivalence study is not always required. A WHO prequalification assessment report (reference HA480) shows that WHO’s guidance allows a waiver for some products, such as an aqueous solution given by injection that contains the same active ingredient at the same concentration as the comparator.

The Tanzanian framework

On Mainland Tanzania, medicines are registered by the Tanzania Medicines and Medical Devices Authority (TMDA). The Tanzania Food, Drugs and Cosmetics (Registration of Medicinal Products) Regulations, 2015 (Government Notice No. 314, published 31 July 2015, made under the Tanzania Food, Drugs and Cosmetics Act, Cap. 219) define bioequivalence and set out the data an applicant must submit. Zanzibar has separate arrangements through the Zanzibar Food and Drug Agency, which this article does not cover.

One limit applies to every generic. Regulators compare each generic with the originator, not with other generics. A 2015 Dutch analysis of bioequivalence studies held in the national regulator’s database notes that current regulation does not require bioequivalence studies between different generic formulations.

Where the quality worry comes from

Quality problems in the medicine supply are real, but they follow a different line from the brand-versus-generic divide. The WHO fact sheet on substandard and falsified medical products (3 December 2024) defines a substandard product as an authorised medical product that fails its quality standards or specifications, or both. A falsified product is one that deliberately or fraudulently misrepresents its identity, composition or source. WHO estimates that at least 1 in 10 medical products in low- and middle-income countries is substandard or falsified.

Neither definition mentions whether the product is a brand or a generic. A registered generic from a licensed supplier, stored correctly, is a different thing from a falsified pack sold through an informal channel. A branded product can also be substandard or falsified.

What can differ between a brand and a generic

Appearance and inactive ingredients can differ. That matters for patients with a known allergy to an excipient (an inactive ingredient), because, as a 2011 article in Pharmacologyonline notes, a generic may be unsuitable for them even when the active ingredient is the same.

Different packs and names also create a counselling problem. A patient given two brands of the same active ingredient may not realise they are taking one medicine twice.

Why generics usually cost less

Registration of a generic rests on quality data and bioequivalence evidence. Bioequivalence tests do not measure price, so the price gap is a separate matter from the evidence on equivalence. This article does not quote local price differences, because a verified Tanzanian comparison was not available when it was prepared.

Three common misconceptions

“A cheaper generic is less effective”

A 2015 systematic review in BMJ Open of 52 studies from 27 countries found that 35.6% of lay people, 28.7% of doctors and 23.6% of pharmacists believed generics were less effective than brands. These figures describe beliefs, not outcomes. The review included only English-language studies and only nine of them surveyed pharmacists, so the pharmacist estimates are less precise.

“A brand name means better quality”

In the same BMJ Open review, pharmacists were the group most likely to rate generics as lower in quality, at 33.4%, compared with 28.0% of doctors and 25.1% of lay people. The review’s table lists a survey of 154 pharmacists in north-central Nigeria in which 54.5% held that view. It is one small survey and says nothing about Tanzania.

“Switching to a generic causes more side effects”

The review’s authors argue that negative views of generics are likely linked to higher side-effect reporting and lower adherence, citing earlier studies. Expectation therefore matters in counselling, whatever the pharmacology.

What a Tanzanian hospital study found

Tanzania’s National Treatment Guidelines and a National Therapeutic Committee circular of 2012 require prescribers to use generic names. A cross-sectional study at Muhimbili National Hospital (Kisamo et al., 2020) analysed 1,001 prescriptions from January to May 2019. Medicines were prescribed by brand name on 71.6% of prescriptions. Vitamin and mineral supplements (34.4%) and antibiotics (26.7%) were the products most often prescribed by brand.

The study covered one hospital over five months, so it cannot be read as a national picture. The authors recommended qualitative work to find out why prescribers use brand names.

What pharmacy teams can do

• Dispense and label by generic name alongside the brand, so patients can recognise the same active ingredient across products. A New Zealand clinical guidance article also advises giving patients a medicines list by generic name, especially when they move between hospital and community care.
• Explain the equivalence evidence plainly. Say that the generic was compared with the originator before registration, and that appearance can differ.
• Check for duplicate therapy when a patient presents with two brands of one ingredient.
• Ask about excipient allergies before substituting.
• Buy only from licensed suppliers and confirm product registration with TMDA. Report a suspected substandard or falsified product to the national regulator, as WHO advises.
• Refer to the prescriber when a patient on long-term treatment reports a change after a switch between manufacturers.